a publication of brussels urban development 2015 online

Transcription

ONLINE
PROCEEDINGS OF ONE-DAY SEMINAR
11/12/2014
The energy future of existing buildings in Brussels:
between preservation and performance
A PUBLICATION OF BRUSSELS URBAN DEVELOPMENT
2015
Thanks
This publication is the result of the proceedings of the
one-day seminar “The energy future of existing buildings
in Brussels: between preservation and performance”, held
in Brussels at the Royal Library on 11 December 2014.
Organised by Brussels Urban Development/Regional Public
Service of Brussels, the project’s steering committee
was made up of Grégoire Clerfayt, Sven De Bruycker,
Caroline Mulkers, Benoit Périlleux, Marie-Laure Roggemans,
Anne Van Loo and Manja Vanhaelen.
We would like to thank everyone who provided their advice,
participation and experience, especially Boris D’or,
Michael de Bouw, Francois Dewez, Celine Jeanmart,
Benoit Priod and Claudine Houbart. We would also like
to thank all those involved, either directly or indirectly,
in the organisation and smooth running of the event and
the publication of these proceedings.
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A PUBLICATION OF BRUSSELS URBAN DEVELOPMENT
2015
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BRUSSELS HERITAGE – ONE-DAY SEMINAR – 11/12/2014
CONTENTS
P.006
EDITORIAL
P.008
A WORD OF WELCOME
Arlette VERKRUYSSEN
P.009
A WORD OF INTRODUCTION
Bety WAKNINE
P.010
WHAT ARE THE REQUIREMENTS FOR
THE ENERGY PERFORMANCE OF
BUILDINGS WHEN RENOVATING?
Michaël GOVAERT
P.016
ARCHITECTURAL HERITAGE
AND ENERGY PERFORMANCE:
COMPATIBILITY CHALLENGES?
Manja VANHAELEN
P.024
URBAN FORMS, TYPOLOGY AND
IMPROVING THE ENERGY EFFICIENCY
OF OLD BRUSSELS BUILDINGS
Julien BIGORGNE
P.036
THE LISTED HOUSES OF THE LE LOGIS
AND FLORÉAL GARDEN CITIES
ADAPTATIONS TO CURRENT ENERGY AND
COMFORT NEEDS
Guido STEGEN
P.048
FINANCIAL IMPACT OF ENERGY
EFFICIENCY MEASURES IN LE LOGIS
AND FLORÉAL
Jonathan FRONHOFFS
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THE ENERGY FUTURE OF EXISTING BUILDINGS IN BRUSSELS: BETWEEN PRESERVATION AND PERFORMANCE
P.056
ANALYSIS OF UNCERTAINTIES IN
DYNAMIC THERMAL SIMULATIONS
FOR OLD HOUSING:
A CASE STUDY OF ONE APPARTMENT AND
ONE HOUSE IN THE PARIS REGION
Julien BORDERON
P.064
RISK ANALYSIS FOR APPLYING
INTERIOR INSULATION IN
HISTORICAL BUILDINGS:
A CASE STUDY OF THE
FORMER VETERINARY SCHOOL
IN ANDERLECHT
Roald HAYEN
P.076
IEDER ZIJN HUIS:
THE RENOVATION OF A MODERNIST
SOCIAL HOUSING TOWER BLOCK
Charlotte NYS
P.094
PRESENTATION AND RESULTS
OF THE “PLAGE” PROJECTS
LOCAL ACTION PLANS
FOR ENERGY MANAGEMENT
Emmanuel HECQUET
P.100
THE BELGIAN BUILDING RESEARCH
INSTITUTE: A CONTRIBUTION TO
HERITAGE MAINTENANCE
EXPLORING THE TRAINING OF HERITAGE
ADVISORS SPECIALISING IN ENERGY
Michael DE BOUW and Sandrine HERINCKX
P.106
SUSTAINABLE RENOVATION
OF A BRUSSELS HOUSE:
A CHALLENGE FOR BUILDING TRADESMEN
Jérôme BERTRAND
P.118
CONCLUSION
Benoît PÉRILLEUX
P.086
THE BRUNFAUT TOWER:
PRESENTATION OF THE CONCEPTUAL
DESIGN CHALLENGES OF A RENOVATION
P.120
COLOPHON
Vincent DEGRUNE
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EDITORIAL
Brussels Heritage online is the first digital edition of the
periodical of the same name. Devoted to the proceedings
of the symposium on “The energy future of existing
buildings in brussels: between preservation and performance”, it contains the contributions presented
during the one-day seminar organised by Brussels
Urban Development, which was held in the Royal Library
of Belgium on 11th December 2014.
The purpose of this seminar was to lay the groundwork
for a collective examination by all administrations
and actors in the heritage and energy sector to find
solutions, over the long term, to achieve a better balance between the necessary preservation of Brussels’
buildings and the no less necessary search for energy
efficiency in these buildings. In order to identify the
issues and determine the key elements for future projects, we invited specialists from Brussels and abroad
and from a variety of backgrounds (including energy
engineers, architects, art historians and engineers)
to share their experiences and thoughts and compare
their perspectives.
The seminar opened with a general outline of the
issues, examined in turn by Michael Govaert and Manja
Vanhaelen via the regulatory texts and a questioning of
the practitioners concerning their implementation and
objectives. Case studies also featured prominently in
the programme for the seminar. The issue of improving
energy performance was first tackled at regional level
as the reduction in consumption that we are aiming for
must be considered in relation to the urban form, as
emphasised by Julien Bigorgne, and not only based on
a particular building in isolation. This broad context is
reflected in the management plan for Logis-Floréal,
presented by Guido Stegen and Jonathan Fronhoffs.
This regulatory text, which takes an innovative approach
to the management of Brussels’ heritage, sets out the
general conservation guidelines for the biggest collection of listed buildings in the Region while also clearly
defining the works that are permitted. In this way, the
Region has developed a clear framework in which conservation objectives can be identified by working on
the buildings on a case-by-case basis, while giving due
consideration to concerns relating to energy, economics, maintenance and comfort.
Specialised topics concerning the assessments to be
carried out prior to any work on a building were also
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addressed via presentations by Julien Borderon and
Roald Hayen; the former examining the uncertainties
associated with thermal simulations applied to old
buildings and the latter reporting on the risks of problems inherent to the use of interior insulation, using
the listed former veterinary school in Anderlecht as an
example.
As the notion of heritage has broadened over the years,
we chose to present examples of renovation involving
two social housing tower blocks. This provided an
opportunity to explore the future of these buildings (the
heritage value of which is often disputed) which are at
risk of demolition even though they contain a number
of tangible advantages from a renovation point of view.
Using these two examples, the underlying issues of
embodied energy, sustainability of fittings and the cultural value of these structures were explored.
Finally, presentations were delivered addressing
actions on the ground and projects concerning better management of energy in these buildings, as well
as raising awareness among residents and training
of trades. This was an opportunity to learn about the
positive impact of the Local Action Plan for Energy
Management (PLAGE) coordinated by Brussels
Environment, the Belgian Building Research Institute’s
joint energy engineer/restorative architect training
project and, finally, to highlight the new challenges facing craftspeople working on the renovation of Brussels’
houses to improve energy efficiency and also preserve
their architectural and structural characteristics.
Through all these themes and the different interpretative frameworks applied to the issues raised, a number of important points of agreement emerged: the
certainty that there is no magic solution; that uncertainties are unavoidable; that the complexity of the
objects on which we work is real and must be better
taken into account; that it is essential for experimentation and evaluations to be carried out; and, over and
above all, that the resident must be the prime focus of
any approach. This analysis can only encourage us to
work together to respond to the challenges of the city
of tomorrow.
Thierry Wauters
Director. Direction des Monuments et Sites.
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A WORD OF WELCOME
It is my pleasure to welcome participants, on behalf
of the Regional Public Service and, in particular,
Brussels Urban Development, to this one-day seminar
on the energy future of Brussels’ buildings.
This seminar arose from an observation that we share
with many other conurbations and towns: thermal
insulation improvement works have become one of
the major issues in projects to renovate and restore
existing buildings.
These works are often complicated, the can be documentation complex and varied, and works are sometimes carried without professional advice. There is
a real risk of such work damaging the architectural
value of buildings and the urban landscape without
necessarily achieving the expected results. However,
we are responsible for the management of a city that
has a heritage character and our duty is to preserve
this character- preserve the heritage that we have
inherited - while making sure that we do not transform the city into a museum. On the contrary, we must
make sure that it will be capable of responding to the
challenges and changes that await it - demographic
boom, energy dependence, mobility, etc. - without
spoiling it. It is a significant challenge.
The energy future of our existing buildings is therefore
a crucial issue which concerns the management of the
city today as well as its future development. This oneday seminar is just one step lead by the desire to conduct a joint debate on the issue, within Brussels Urban
Development on the one hand, and between Brussels
Urban Development and Brussels Environment on the
other.
efficiency; preserving the heritage value of buildings
and the urban landscape; economic and social constraints; etc. Let’s not bury our heads in the sand; this
is a difficult process and the subjects are complex,
which is why it is becoming urgent and essential to
conduct a joint reflection rather than examining the
issues separately. It is also important that this process
of reflection involves the experts - the operators in
the field - from the energy, environment, architecture,
heritage conservation, construction, urban planning
and urban sociology sectors. This is why I have been
delighted to see so many colleagues from this sectors in attendance.
I hope that points of view will be compared, that
knowledge, practices and experience will be shared
and that this discussion fuels a joint debate so that we
can develop operational policies and tools in future in
consultation together.
Before handing over to Mrs Bety Waknine from the
Minister-President’s office, I would like to thank all
the departments from Brussels Urban Development
and, in particular, the Monuments and Sites
Department (which coordinated this project), Brussels
Environment, as well as the Royal Commission of
Monuments and Sites (which participated in the
preparation of this seminar). I would also like to thank
the speakers for having responded to our invitation.
We all have to confront these problems and difficulties in our role as public managers and we are obliged
to provide solutions to our fellow citizens and advise
them in these complex and costly matters.
These solutions must be aimed at reconciling the
various issues of sustainable development: energy
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Arlette Verkruyssen
General Director of Brussels Urban Development
of the Brussels Regional Public Service
A WORD OF INTRODUCTION
On behalf of the Minister-President, I’d like to thank
all the participants for taking part in this seminar in
such large numbers.
The government’s adoption of the Brussels Air,
Climate & Energy Code in May 2013 demonstrated
its firm intention to take action to reduce greenhouse
gas emissions and gaseous pollutants while ensuring affordable access to energy for households in the
Region. This code, based on the Air-Climate-Energy
Plan, includes among other things the measures to
be implemented to improve energy efficiency in public
buildings and achieve targets for reducing energy consumption, namely a 30% reduction in greenhouse gas
emissions by 2025 compared to 1990 levels.
The issue of energy efficiency is generally associated
with buildings (both residential and non-residential),
tertiary activities and transport. Insofar as buildings
are concerned, housing is one of the biggest consumers of energy. There are obviously a variety of reasons for this: lack of building maintenance, obsolete
technical installations, poor insulation, inappropriate
occupation or use of buildings, etc. The combination of
these factors can result in energy insecurity with significant financial and health implications, particularly
among already economically disadvantaged populations.
The issue of energy efficiency in existing buildings
is fundamental. The Region already has a range of
tools available to it to take action and improve the
situation: four-year plans by the Brussels-Capital
Region Housing Company; Sustainable or Renovation
Neighbourhood Contracts; building façade improvement grants; subsidised works and mobility plans.
Nevertheless, increasing the number of such mechanisms does not always make them effective. The
onerousness of the procedures involved, the waiting
time, the complexity of the mechanisms and the lack
of monitoring of results has not always enabled the
expected outcomes to be achieved. This is why the
Government wanted, at this opening session of parlia-
ment “to assess and amend the system of renovation
grants so that they are primarily aimed at those who
really need them (...) and reassess the system for renovation and energy grants (...) with a view, in particular, to uniting the two mechanisms”. The government
also wanted to shift the focus of current energy grants
from new passive and low energy construction to
energy saving works. This reassessment should also
enable just consideration to be given to the architectural and heritage quality of our City and Region. The
balance between conserving heritage and energy must
be achieved. Our actions must be aimed at finding this
balance between building performance and preservation; such a balance can only be found if we take into
account the specific characteristics of the old fabric
in order to work on buildings in an intelligent manner
and reduce energy costs without creating structural
problems that would endanger the long term objectives being pursued. By renovating the city, enhancing
our heritage, working on the urban fabric and improving living conditions, we are looking towards the long
term.
Clearly, the efforts required are significant, the project complex, the parties involved numerous and the
resources limited. However, it is possible to reconcile heritage and energy; there are numerous links
between the two issues and by encouraging discussion, by bringing together the different trades, by posing issues and debating what’s at stake, common lines
of thought can be mapped out. Faced with such complex challenges, a cross-disciplinary effort to raise
awareness and advise our fellow citizens will have to
be carried out. The administrations and associations
will have an essential role to play.
Thank you and I hope you have a day filled with intense
discussion and ideas!
Bety Waknine
Deputy
Minister-President Rudi Vervoort.
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WHAT ARE THE REQUIREMENTS FOR
THE ENERGY PERFORMANCE OF BUILDINGS
WHEN RENOVATING?
MICHAËL GOVAERT
ENERGY DIRECTORATE, BRUSSELS ENVIRONMENT
SINCE 2 JULY 2008, THE ENERGY PERFORMANCE OF BUILDINGS (EPB) WORKS
REGULATION, WHICH IMPOSES VARIOUS ENERGY PERFORMANCE REQUIREMENTS,
HAS APPLIED TO RENOVATION PROJECTS SUBJECT TO PLANNING PERMISSION IN
THE BRUSSELS-CAPITAL REGION
The purpose of this presentation
is to outline the energy performance requirements applicable to
renovation projects and demystify
the regulations. Indeed, there are
numerous fears circulating within
the sector that are often the result
of miscommunication.
THE CONTEXT BEHIND
THE ENERGY PERFORMANCE
OF BUILDINGS (EPB)
REGULATION
As the audience is likely already
aware, we currently face the dual
dilemma of global warming and
increasing energy prices. The
issues that we have to deal with
are therefore both environmental
and social. In Brussels, buildings
account for 70% of energy consumption; they are therefore the
main source of greenhouse gas
emissions and one of the main
sources of atmospheric pollution
in the city.
Since 2008, the Brussels-Capital
Region has had a legal instrument
at its disposal for improving the
energy performance of buildings,
namely the Ordinance on Energy
Performance and the Internal
Climate of Buildings. This ordinance transposes into Brussels
law the 2002 European Directive
on the Energy Performance of
Buildings, the measures of which
were strengthened in 2010 in light
of the deteriorating situation. In
this respect, the second draft of
this directive provides for new
buildings to be almost zero-energy
by 2021. The Brussels Air, Climate
and Energy Code (COBRACE)
has incorporated these new
European provisions in its EPB
section. They come into force on
1st January 2015. There are multiple objectives: reducing primary
10 | What are the requirements for the energy performance of buildings when renovating?
energy needs to preserve natural
resources; reducing CO2 emissions to combat climate change;
improving the energy efficiency,
internal climate and the technical
installations of buildings; as well
as informing any future owner or
tenant about the energy rating of
the desired property via the EPB
certificate.
As part of the rewriting of the
ordinance with a view to its incorporation within COBRACE, the
“EPB Works” administrative procedure has been redesigned and
simplified. I will therefore explain
the “EPB Works” Regulation as it
works in practice from 1st January
2015. It is worth noting that this
designation refers to the section
of the EPB regulation devoted to
the energy performance requirements imposed within the context
of a construction or renovation
project.
THE SCOPE OF APPLICATION
OF THE “EPB WORKS”
REGULATION
school. It is on the basis of the unit
that the nature of the works and
the occupancy are determined.
As a first step, it is important to highlight that the EPB does not apply to
all buildings and to all occupancies.
The European Directive specifies
exceptions, including places of worship, industrial or craft workshops,
and temporary structures, among
others. Only buildings occupied on
a continuous basis and in which
energy is used for people’s comfort
come within the scope of the EPB.
What’s more, the “EPB Works”
regulation only applies within the
context of an application for planning permission. It does not therefore apply to works that involve only
renovations that are identical to
the original building. It concerns
all new buildings and, in buildings
undergoing renovation, only buildings on which works are being
carried out on the envelope and
that may potentially influence the
energy efficiency of the building. It
does not therefore concern maintenance, painting or application of
rendering without insulation.
The EPB Regulation defines four
distinct categories of work (table 1):
1° New units (NU) which correspond to new-build projects,
e.g. a house constructed on a
greenfield site.
2° Units considered as new (UCN).
These have caused the most
ink to be spilled. This category
is the result of an amalgamation between units that have
been extensively renovated and
units considered as new. Units
considered as new are defined
as units where works are carried out on at least 75% of their
heat loss surface and by the
replacement of all the technical installations. This category
is only encountered very rarely:
it concerns, for the most part,
buildings that are completely
stripped and of which only the
THE EPB UNIT, NATURE OF
WORKS AND OCCUPANCIES
It is the nature of the works and
the occupancy that determines
the EPB requirements applicable
to a project. In order to find out
what these requirements are, the
project is split into buildings and
EPB units. While the meaning of
building is clear to everyone, that
of unit needs to be explained as it
is specific to the EPB. An EPB unit
is a part of a building or a building
complex. It is formed by a group of
adjoining premises which are used
for a single occupancy and which
could be sold or rented separately.
It typically concerns an apartment,
a house, an office building or a
Nature of
worksaccording
to COBRACE
structure is retained. It should
be specified that the heat loss
surface corresponds to all of
the thermal envelope, that is to
say the façades, roof, floor slab,
etc.
3° Extensively renovated units (ERU)
which are defined as units where
works are carried out on at least
50% of their heat loss surface and
on at least one or two technical
installations, depending on the
occupancy.
4° Finally, simply renovated units
(SRU) which are defined as
units where works are carried
out on the heat loss surface and
on technical installations that
are not covered under the other
definitions.
Extensively renovated units and
simply renovated units can be
distinguished from each other by
different procedures. However,
currently, the requirements are
strictly the same.
NU
UCN
ERU
Percentage
of works,
on the heat
loss surface,
influencing
the EPB
100%
≥ 75%
≥50%
Works on
technical
installations
New
technical
installations.
Works on the
heat loss
surface and
replacement
of all
technical
installations.
SRU
Works
on the heat
loss surface
(and on
technical
Works on the
installations)
heat loss
surface and on not covered
at least one or by the other
definitions.
two technical
installations
depending on
the occupancy.
Table 1
Summary of nature of works. The EPB requirements for high energy efficiency
inspired by the passive standard only apply to new units and units considered
as new, and only for three types of occupancy: housing, offices and schools
(source: BE).
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THE EPB REQUIREMENTS
FOR INSULATION AND
VENTILATION
1.1 W/m2K for the glass. This is
what is traditionally available on
the market.
For all EPB units that are extensively or simply renovated, only
two requirements have to be satisfied: insulation and ventilation.
The insulation requirement solely
concerns the modified walls of
the envelope, namely (where
appropriate) the walls, floor, roof
or windows. Where a window is
added or replaced there is also a
ventilation requirement for the
premises in question. In fact, the
EPB is not only connected with
energy consumption; it is also
aimed at improving the quality of
the internal air. These two requirements, insulation and ventilation,
exist in an identical form in the
three Regions of the country. As
regards the insulation requirement, the Regions have (with the
support of the Belgian Building
Research Institute (BBRI)) set
the heat transmission values that
every project, including any modification of walls, must satisfy when
applying for planning permission as
of 1st January 2014. For walls and
roofs, the maximum U-value is 0.24
W/m2K. This value gives the following indicative thicknesses (tables
2 and 3), which vary depending on
the type of insulation. In this way,
the thickness of the insulation for
a wall will vary from 9 to 17 cm.
While these thicknesses seem
significant, the requirements are
cost optimal, as required by the
European Directive. When carrying
out works it is important to keep
in mind that they are generally not
repeated for at least thirty years
and it is therefore important to
have a long term vision and reflect
on the irreversibility of the changes
made and what impacts they will
have on energy over time. For windows, the maximum U-values are
1.8 W/m2K (including frame) and
The ventilation required when
a window is replaced or added
ensures a healthy climate by
removing waste air (humidity,
domestic pollutants, etc.) There
are four systems of ventilation:
natural ventilation; mechanical
ventilation; and hybrid versions of
the two systems. The EPB does
not require a particular system but
simply sets down the rates of ventilation which, for housing, are well
known by the sector (those of the
NBN50001 standard, in force since
1991). Added to this requirement
for healthy ventilation is (in the
Structural element
Umax (W/m2K)
Rmin (m2K/W)
1. WALL DELINEATING THE PROTECTED VOLUME excluding walls forming
the separation with an adjacent protected volume
1.1. TRANSPARENT/TRANSLUCENT WALLS excluding doors and garage
doors (see 1.3), curtain walls (see 1.4) and glass bricks (see 1.5)
Uw max = 1.8 and
Ug max = 1.1
1.2. OPAQUE WALLS excluding doors and garage doors
(see 1.3) and curtain walls (see 1.4)
1.2.1 Roofs and ceilings
Umax = 0.24
1.2.2. Walls not in contact with the ground excluding walls referred to
in 1.2.4
Umax = 0.24
1.2.3. Walls in contact with the ground
Rmin = 1.5
1.2.4. Vertical and sloping walls in contact with crawl spaces or with a
cellar outside the protected volume
Rmin = 1.4
1.2.5. Floors in contact with the outside environment
Umax = 0.3
1.2.6. Other floors
Umax = 0.3 or
1.3. DOORS AND GARAGE DOORS (including frame)
Ud max = 2.0
1.4. CURTAIN WALLS (according to prEN 13947)
Ucw max = 2.0 and
Ug max = 1.1
1.5. GLASS BRICK WALLS
Rmin = 1.75
Umax = 2.0
2. Walls between two protected volumes situated on adjacent plots
Umax = 1.0
4. Opaque walls inside the protected volume or adjacent to a protected
volume on the same plot excluding doors and garage doors
Umax = 1.0
Table 2
Insulation requirements. U/R-values (since 1st January 2014) (source: BE).
Type of wall
Umax since
01/01/2014
(W/m2.K)
Lambda value of
the insulation
Thickness in cm of
mineral wool type
insulation
(λ = 0.045 W/mK)
Thickness in cm of
plant wool type
insulation
(λ = 0.04 W/mK)
Thickness in cm of
synthetic foam
type insulation (λ =
0.035 W/mK) (3)
Thickness in cm of
PIR foam type
insulation (λ =
0.023 W/mK)
0.045
0.04
0.035
0.023
Sloping (or flat)
roof, 80%/20%
insulation between
rafters
0.24
26
25
24
20
Flat (or sloping)
roof, continuous
insulation on
wooden structure
0.24
16
15
13
9
Flat (or sloping)
roof, continuous
insulation on
concrete structure
0.24
17
15
13
9
Exterior wall
(29 cm bricks),
external insulation
0.24
17
15
13
9
Exterior wall
(14 cm blocks),
external insulation
0.24
17
15
13
9
Exterior wall
wooden framework
0.24
20
19
17
14
Heavy floor in
contact with
exterior
12
11
10
7
Heavy floor on
ground
9
8
7
5
Heavy floor over
cellar with door
and window
9
8
7
5
Table 3
Insulation requirements. U/R-values (since 1st January 2014). Example of indicative
insulation thicknesses that comply with the EPB regulation (source: BE).
case of housing) intensive ventilation, which enables a rapid solution to be provided for problems
of overheating or excess pollution.
In this case, the requirement is a
simple obligation to have a minimum opening.
POSSIBLE EXEMPTIONS
It is sometimes impossible to comply with the requirements. For this
reason the Brussels Government
has provided the option of applying for exemptions, both for renovations and new builds. The client
submits the application before the
project begins, either to Brussels
Environment, or (if it concerns a
simple renovation) to the issuing authority, which assesses the
application and then grants or
refuses the exemption. The client may submit an appeal to the
Government if not happy with the
decision.
There are two types of exemptions.
The first is called a “heritage”
exemption as it concerns listed
buildings or buildings that are
included on the list of protected
structures. This type of exemption
applies where full, or even partial, compliance with the requirements would affect conservation
of the architectural heritage. It is
granted directly by Brussels Urban
Development. The second case
concerns non-listed new buildings,
buildings considered as new and/
or renovated buildings. The exemption is possible where full or partial
compliance with the requirements
is technically, functionally or economically impracticable.
An exemption will be granted:
1° For technical reasons, where
the works pose problems for
the stability, fire resistance, air
or water tightness of the wall or
building, or if there is no material or product available that
enables compliance with the
requirements.
2° For functional reasons, where
the insulation and ventilation works or additional works
subsequent to such works
endanger the use of the building, disproportionately harm
the architecture or result in
non-compliance with planning
constraints.
3° For economic reasons, where
the cost of the insulation and
ventilation works, including any
additional works subsequent to
the insulation and ventilation
works, is three times greater
than the cost of works of the
same type in another building.
Between 2008 and 2014, only 37
applications for exemptions were
submitted to Brussels Environment
and more than two thirds were
granted. Those based on the
requirements drawn from municipal regulations were systematically approved. From 1st January
2015 exemptions for simple renovations are no longer processed by
Brussels Environment but instead
are handled directly by the authorities that grant planning permission. Finally, it is worth reiterating
that there is no obligation to comply
with these requirements. Where a
project does not comply with them,
the client will be required to pay a
fine but planning permission will
not be refused and they will not be
required to make it compliant.
lation. We are also supported by
a scientific consortium composed
of the BBRI, consultancy firms
and universities. We invite you
to participate in this continuous
improvement loop. Respecting
heritage and improving energy efficiency can be mutually beneficial,
particularly through regular consultation between the actors concerned. Brussels Environment is
about more than just a regulation;
it’s also a financial support that
can be activated via the “energy
bonuses” and the “Brussels green
loan”. It also comprises technical
support, assistance with applying the regulation and assistance
with technical design. There are
many information tools available on the Brussels Environment
website (the “EPB Works” pages,
the Sustainable Buildings guide,
etc.) Finally, we organise an entire
range of training courses and seminars on sustainable construction
aimed at training for excellence.
We have outsourced a support service for professionals called the
“Sustainable Buildings Facilitator”
service. As regards assistance for
private individuals, every municipality has an EPB official who
assists people in understanding
the legislation. We also support the
“regional information desks” that
provide citizens with personalised
support for their energy problems.
Translated from French.
CONCLUSION
The EPB regulation is evolving. In
order to do so it relies on feedback
from professionals, architects and
contractors as well as the administrations and municipalities who
are helping us to apply the regu13
ONLINE
EXEMPLARY BUILDINGS
The experience gleaned from
exemplary buildings (Batex) constitutes a source of highly interesting information. These projects
went further than the EPB Energy
Regulation recommended at the
time. They were followed up by
experts and are currently monitored, which enables us to inform
future discussions with concrete
facts. Each Batex is presented in
detail on the Brussels Environment
website.
Fig. 3
Avenue Ducpétiaux 47 in Saint-Gilles.
Low-energy renovated standalone
house. The façade was retained. It is
internally insulated on the non-listed
internal sections which concern three
of the four floors. The owners opted
for the installation of a second window
set back from the first in order to
preserve the original aspect
(A. de Ville de Goyet, 2015 © SPRB).
Fig. 1
Rue Rubens 92 in Schaerbeek. Low
energy, single-family dwelling house,
39 kWh/m2/year. The front façade was
retained and the joinery, although
triple-glazed, was reproduced to exactly
match the original setup. The front
façade was internally insulated and, in
order to respect the heritage, certain
bands were left without any insulation
Fig. 2
Avenue Besme 107-109 in Forest.
Apartments and offices.
Art Deco style low energy building.
The window frames on the front façade
were retained and renovated with
the single-glazing being replaced
with double-glazing 1.1
Fig. 4
Rue du Comte de Flandre 45-51 in
Molenbeek-Saint-Jean. Mommaerts
workshops, the front façade of which is
listed. It was not insulated internally
but a low energy solution was,
nevertheless, achieved.
Fig. 5
Rue Royale-Sainte-Marie 237 in
Schaerbeek. Apartment building.
Almost passive example of a building
included on the list of protected
structures, the façade of which
was retained
WEBSITE
• All information about the EPB,
training courses and seminars is
available on the website:
www.environnement.brussels
SUPPORT SERVICES
Professionals
• Sustainable building facilitator:
[email protected]
Private individuals:
• Municipal EPB officers
• Maison de l’énergie/Energiehuis:
www.maisonenergiehuis.be
Quelles exigences PEB
en rénovation ?
Welke EPB-eisen
bij renovatie?
Depuis le 2 juillet 2008, les
projets de rénovation soumis à un
permis d’urbanisme en Région de
Bruxelles-Capitale sont concernés
par la réglementation Travaux PEB
qui impose différentes exigences
de performance énergétique.
Dans la plupart des cas, il s’agira
d’exigences d’isolation des
parois et de ventilation. Pour
les rénovations de plus grande
envergure (plus de 75 % de la
surface du mur), dont l’ampleur
des travaux est à comparer à une
construction neuve, le projet devra
également répondre à de nouvelles
exigences inspirées de l’expérience
des Bâtiments exemplaires et du
standard passif.
Voor renovatieprojecten die
onderworpen zijn aan een
stedenbouwkundige vergunning
in het Brussels Hoofdstedelijk
Gewest. In de meeste
gevallen gaat het om eisen
inzake isolatie van muren en
ventilatie. Voor grootschalige
renovaties (meer dan 75% van
de uitgevoerde werkzaamheden
aan de oppervlakten met
warmteverliezen), waarbij
de omvang van de werken
vergelijkbaar is met nieuwbouw,
zal het project eveneens moeten
voldoen aan nieuwe eisen
geïnspireerd op de ervaring met
de voorbeeldgebouwen en de
passieve standaard.
15
ONLINE
ARCHITECTURAL HERITAGE
AND ENERGY PERFORMANCE:
COMPATIBILITY CHALLENGES?
MANJA VANHAELEN
MONUMENTS AND SITES DEPARTMENT
THIS ARTICLE COMPRISES AN OVERVIEW OF THE ISSUES WITH WHICH THE
MONUMENTS AND SITES DEPARTMENT IN PARTICULAR, AND THE HERITAGE
SECTOR IN GENERAL, ARE CURRENTLY CONFRONTED WHEN APPLYING LEGISLATION
REGARDING THE IMPROVEMENT OF THE ENERGY PERFORMANCE OF BUILDINGS.
With recent advances in the battle to reduce CO2 emissions and
improve the energy efficiency of
buildings, the heritage sector has
been looking for a new way to deal
with architectural heritage within
that context. The assumption that
heritage and energy performance
are placed in direct opposition may
seem like something of a caricature; in many building dossiers,
the applications we are confronted
with in reality sadly do resemble
this harsh depiction of two sides
performing contradictory actions
on each other’s terrain.
THE TASK OF THE HERITAGE
CONSERVATOR
Let us first take a closer look at
the role of the heritage conservationist. Essentially, the heritage
conservationist is charged with
preserving heritage; he or she
ensures that buildings, as expressions of an architectural past, of
culture and of savoir faire, are preserved. This includes preservation
of materials from the past, monuments and their valuable aspects
and facets such as decorations,
details, materials, techniques,
architecture from the various construction periods (from Gothic to
Renaissance and Eclecticism to
the late Modernism of the 1950s
and 1960s), and the preservation
of expression, concept and urban
design context. In this way, monuments are passed on to future generations as witnesses of history,
culture, science and knowledge.
Heritage conservationists guide
monuments towards their future
while battling against natural erosion and the ageing of buildings,
damage caused by natural disasters, wars or even previous restoration attempts. They also strive
to guide the monuments through
the heritage renewal, through renovations, new allocations, adaptations to styles, flavours, comfort
requirements and of course the
energy performance improvement requirements. Exactly what
is deemed valuable depends on
16 | Architectural heritage and energy performance
the monument. Sometimes it is a
unique expression, sometimes it
is the old material with a unique
historical testimony, sometimes it
is the concept or idea behind the
building rather than the materials.
The heritage conservationist’s
task is supported by a theoretical framework based on the 1964
Venice Charter. The legislation
in use and under development
today also stems from this charter. The two cornerstones of this
restoration philosophy are as follows. Firstly a good knowledge of
the monument is imperative; this
highlights the importance of thorough research prior to any intervention, both historical and technical as well as any other research.
This allows us to recognise what is
truly valuable and make a decision
on how to intervene or not. The
second cornerstone is respecting
a hierarchy in the intervention.
Maintenance must always be the
top priority. If maintenance alone
does not prove sufficient, restoration and repairs are embarked
Fig. 1 and 2
Typical Brussels buildings. Left: Brussels residences around the turn of the last century (Ch. Bastin & J. Evrard © GOB);
right: Neoclassical façade facing the Pachecogodshuis, Fermerijstraat, arch. H. Partoes, ca. 1830 (© GOB). None of these
buildings can be insulated on the exterior without impacting their heritage value.
upon. An element is replaced only
as a last resort and when absolutely necessary. Reconstruction of
an identical model is the exception
rather than the rule. This approach
is highly sustainable in and of itself.
I will summarise, based on this
intervention philosophy and starting from the essence of the heritage conservationist’s role, why in
reality the heritage sector almost
always locks horns with the energy
sector, despite the energy performance exemption regulation
applicable to listed monuments.
This regulation is clearly necessary, but simultaneously illustrates the unresolved discrepancies. Furthermore, whether or not
a project has permission to deviate
from the standard, the applicant’s
starting point justly remains the
improvement of the situation and/
or an increase in comfort.
The requirements of the Energy
Performance of Buildings (EPB)
energy performance legislation
for building and renovating only
apply when works are being carried out and a building permit is
also required. However, in reality
the opposite happens: an application for a building permit tends to
be submitted in order to be able to
carry out works with the intention
of meeting the EPB standard.
The following section details the
entire envelope of the building, the
skin which forms the transition
between a listed and unlisted environment, and the intervention plan
for improving energy performance.
INSULATION OF THE FAÇADE
Historical façades come in many
forms: these might be brickwork
façades, austere or polychrome, with
decorative masonry, interspersed
with limestone or façades made
solely of limestone, with sculptural elements or a rather plain
Neoclassical façade in white lime
plaster with simple mouldings (fig.
1 and 2). These examples are very
typical of the Brussels development.
None of these can be insulated on
the exterior without losing their
heritage value. Exterior insulation
may be possible on very simple
façades, though a great deal of
detailed work remains with such
an intervention. What about cohesion with the existing windows?
These will be partially covered due
to the thickness of the insulation,
will appear to be embedded deeper
into the façade than they originally
were, and the sills will need to be
adapted in order to disperse water.
What about the eaves and cohesion with receding and protruding
features? This type of intervention
often leads to visually awkward or
technically half-hearted solutions.
The ultimate solution for a newbuild project often proves to be a
cumbersome operation and never-ending story for a renovation - if
I renovate the façade, then I should
also do the windows, the roof, the
gutters, the extension, the neighbour, etc.
If exterior insulation is not possible, then we must use interior
17
ONLINE
Fig. 3
Dining room in the residence of architect Jamaer, 1876, Stalingradlaan 62,
1000 Brussels (© KIK-IRPA). The rich décors that decorate not only grand
Brussels residences, but more modest homes too, make interior insulation
impossible without removing the heritage elements.
Fig. 4
The windows and doors are an integral
part of the façade architecture.
Brugmannlaan 30, arch. Lesec et
Quoilin, 1937 (© GOB).
Fig. 5
Diongre garden city, arch. J. Diongre,
1925, Sint-Jans-Molenbeek,
(Ph. de Gobert© KCML).
The replacement of the historical
woodwork has radically altered the
character of the façade.
insulation. Unfortunately, this is
also often impossible from a heritage point of view because of historical buildings’ décors. Figure 3
we see elegant mouldings, colours
and panelling. It is obvious that
you cannot just glue insulation
board onto this. Nor is this type of
décor reserved solely for so-called
“top-class” heritage. The interior
of many Brussels middle-class
homes are quite similar to this.
This contributes to the richness
of the Brussels heritage. Modern
buildings and concrete structures
do not suffer as much from the
new, smooth look, but in these
cases the technical challenge of
solving cold bridges is often a difficult problem.
HISTORICAL WOODWORK
Let us now concentrate on the
façade and the historical woodwork, the windows and doors.
Each period, typology and architec-
tural style is characterised by a different type of woodwork, bringing
great diversity to the architectural
heritage of Brussels. The windows
and doors contribute as no other to
the coherent image of the façade
and the architecture and are in
some cases even small works of
art themselves (fig. 4 and 5). They
bear witness to the technique and
the craftsmanship of yesteryear.
But they could also be considered
elements of valuable and precious
materials: 150 year old oak, for
example, is particularly sustainable. Thanks to its assembly, historical woodwork also allows for easy
local repairs. Consequently these
elements can attain a considerable
life span (fig. 6 and 7).
Fig. 6 and 7
Restoration of doors, Vanderschrickstraat, 1060 Brussels (© GOB).
Some of this historical woodwork
can be perfectly equipped with
double glazing, subject to adaptation of the groove to accommodate
the thicker, double-glass sheet. In
most cases however, the necessary fitting of a thicker glass sheet
means that the woodwork must
also be replaced. Not only can a
groove often not be made large
enough, but the original woodwork is often not strong enough to
carry the extra weight of the glass
sheets. Furthermore, extra airtightness is also often a requirement.
In this circumstance the choice is
often made to use a remake of a
quasi-identical model. Depending
on the quality of the original woodwork, this may or may not be tolerated. Even if the remake is a solution for woodwork of low value, it is
not a solution from a heritage point
of view if the original woodwork
is still in good condition or has a
design of exceptional quality.
Fig. 8
Fig. 9
Fig. 8 and 9
The quality of the glass also influences
the choice of intervention. Decorative
glazing and remnants of glass
production from the past, such as
pulled and blown glass or crystal,
require a different approach (© GOB).
Fig. 10
In many cases, double glazing or
secondary glazing can be an effective
and technically feasible solution.
It has been used as a solution for a
long time now. Knuyt de Vosmaer
House, Rue du Congrès/Congresstraat
in Brussels (© GOB).
Another aspect is the quality of the
glazing itself, because even if the
window frame is strong enough
for an insulating glass sheet, decorative glazing and examples of
remnants of glass production from
the past (such as pulled and blown
glass, crystal, etc.) still require a
different approach (fig. 8 and 9).
In many cases, a double window or
secondary glazing can be a good
and technically feasible solution,
yet this is only used sporadically
(fig. 10). Even when replacing a
window by a higher performance one,
this too can become an ongoing saga.
19
ONLINE
An assessment must be made
as to how this new level of performance relates to the original
environment, which is of course
lower in performance. Installing
high-performance glass in a
non-insulated wall must be done
with care to ensure that a healthy
interior climate is maintained. It is
also usually necessary to insulate
the walls (at least partially) or to
install a well-functioning ventilation
system. In many cases, adapting
the level of insulation can provide
a solution.
Fig. 11
INSULATION OF THE ROOF
As long as an insulation mat is
placed between the rafters - i.e.
within the material contours there is usually no problem with
the roof. However, the standard for each building element
requires more; extra insulation
on the exterior is often a solution,
but it is a very awkward measure
in larger wholes, such as the Le
Logis-Floréal garden cities (fig. 11).
In that case, raising the roof (a necessary step to accommodate the
extra exterior insulation) must be
carried out in consultation with the
neighbours so that the entire row
can be renovated, thus avoiding
unevenness and awkward-looking
connections in the roof surfaces.
Even then, cohesion with the
façade is not easily solved. The
austerity and simplicity of these
houses means that few new elements and details suit them.
It becomes even more difficult with
a roof with dormer windows (fig. 12
and 13); the architectural relationships become distorted and the
ornaments lose their elegance due
to a somewhat inflated effect.
Self-supporting systems are often
opted for in order to lessen the
Fig. 12
Fig. 13
Fig. 11, 12 and 13
Insulation of the roof is indisputably an energy efficient solution.
Nevertheless, the problems of installing it around a dormer or on a
raised roof over terraced houses must be thoroughly assessed
before installation takes place.
formance manifests as a conflict
between two sides: restoration-intervention.
For instance, a thorough investigation of the monuments’ building elements might be conducted, but the
evaluation of their value is threatened by performance requirements
which are inflexible and have top
priority. There is consequently no
more room for the study.
Fig. 14
Hôtel Dewez. Lakensestraat 73,
Brussels. Loft, view of the roof
trusses and beams
(© KIK- IRPA).
Fig. 15
Roof support with visible
panels, municipality school
indoor play area no. 6,
Bordeauxstraat 14-16,
Sint-Gillis, 1891, municipality
arch. Ed. Quétin (© GOB).
load on the original structure and
to apply good, complete insulation.
Because these leave the physical
space within the original structure
of the roof untouched, the extra
height becomes even more noticeable (easily 15 cm).
Interior insulation is also an option,
though of course not if the roof’s interior surface has an aesthetic finish
as shown in the example in figure 14.
Skylights made of classical T, L
and I moulding which form complex, refined structures cannot (in
most cases) bear the weight of
insulated double-glazing or safety
glass (fig. 15 and 16). In many
cases they are rebuilt with sturdy,
modern mouldings.
The extra load of the added insulation often causes structural
problems, thus making the original roofing beams structurally
unsuitable. They must therefore be
supported or replaced, sometimes
with the replacement of the entire
roof as a consequence.
HERITAGE CONSERVATION
VERSUS ENERGY
PERFORMANCE
The contradiction between heritage preservation and energy per-
Not only is research into the value
of the existing elements lacking,
but the evaluation of the effects
and side-effects of the mandatory improvements are seldom
really thoroughly examined. Nor
is the actual performance of old
buildings carefully examined;
real knowledge of the buildings
and all their characteristics has
not yet been acquired. The limited research we do have already
shows, for example, that the values for actual energy consumption deviate greatly and are mostly
much lower than the theoretical
values. We seldom see evaluations
for the prioritised improvements to
be carried out or a thorough investigation to determine what the
most gainful intervention actually
is. The intervention occurs before
knowledge has been acquired and
research carried out.
In a second example, the measures proposed or taken might be in
complete contrast to the sustainable intervention hierarchy.
These examples clearly illustrate
that in the approach to improve
the energy consumption of the
elements in existing buildings,
replacement and reconstruction
often take precedence and have
become more the rule than the
exception. This is not at all the
objective of heritage preservation
and actually completely misses the
point.
21
ONLINE
in which energy is generated and
how people use and maintain their
buildings; then the same questions
can be asked on both of the opposing sides - heritage and energy and common answers formulated.
Fig. 16
Preschool, indoor play area after being restored to its original
condition, Sint-Gisleinsstraat, arch. V. Horta, 1895
(Ch. Bastin & J. Evrard, 2000 © KCML).
The various examples cited above
also illustrate how an intervention
to one element often means that a
much larger intervention subsequently becomes necessary: insulating the roof quickly becomes
replacing the entire roof; insulating windows becomes replacing windows; insulting the façade
becomes replacing the façade.
In principle, rebuilding monuments with respect for the original appearance but resulting in a
high energy performance version
is not part of the heritage conservationist’s task. Reconstructing
the image, and nothing more - and
many interventions intended to
improve energy performance have
this result - goes hand in hand with
the loss of genuineness, authenticity. It’s a new façadism.
Such restorations are no longer
a sustainable intervention either,
and not in the spirit of the task
of heritage preservation: that is,
to preserve, repair and reuse as
much as possible, taking the value
of the elements and the maximum
possible life span of the materials
into account.
The extent to which interventions
require radically altering the contours of existing buildings makes
it an expensive undertaking. The
costs are not always in balance
with the benefits. Indeed, quite
the contrary can be true: making
buildings energy efficient while
preserving the heritage appearance comes with a very high price
tag. This can mean interventions
which are out of proportion on several levels.
However, improving the energy
performance of buildings also
plays a role in sustainability. If we
take a step back and shift our focus
from the performance requirements for each individual building
component to take a more global
view, envisioning a long-term
future; if not every element must
meet maximum performance criteria; if we also consider the way
The improvement of the energy
performance of existing buildings
also raises questions regarding the
life span of the materials; whether
replacement is necessary; and
whether replacement is dealt with
in a responsible manner, such as
taking into account the energy
needed for waste disposal and
production of new materials, or
whether we can reuse materials.
In this common field, it must be
possible to examine the elements’
specific values (material, cultural,
financial, historical, etc.). it must
also be possible to examine the
intrinsic qualities of the existing
buildings and to evaluate whether
or not we can operate them or use
them in a more energy-efficient
way. Consider, for example, inertia,
density, ventilation options, etc.
It must be possible to search for a
healthy balance between the extent
of the operations and the potential
benefits (financial, energy-related,
material, etc.). Is there a good return
on investment time? It must be possible to evaluate the real impact of
the interventions by measuring the
results in order to adjust calculations and models. Finally, it must
also be possible to carry out a thorough analysis of the possible risks
and the side-effects (condensation,
frost, moisture, etc.).
This way of thinking will lead to
a global approach and higher
global-efficient performance; an
upgrade at building, block and city
level; and to high energy performance historical cities.
Translated from Dutch.
Patrimoine architectural et
énergie : des enjeux conciliables ?
Bouwkundig erfgoed en energie:
verzoenbare uitdagingen?
Il existe un paradoxe dans la
manière d’aborder la conservation
du patrimoine architectural
et l’économie d’énergie.
Actuellement, les rénovations
pour raisons d’économie d’énergie
sont de plus en plus nombreuses
et touchent un grand nombre de
bâtiments historiques, classés ou
non. S’il apparaît évident qu’un
bien à caractère patrimonial
doit participer à l’effort de
réduction des gaz à effet de serre,
il apparaît tout aussi évident
que les interventions menées
doivent prendre en compte les
caractéristiques architecturales et
constructives de ce bâti, pour que
la démarche ne soit pas contreproductive.
Er bestaat een tegenstelling
tussen de aanpak voor het
behoud van het architecturaal
erfgoed en de maatregelen
voor energiebesparing. Het
aantal renovaties met het oog
op energiebesparingen neemt
tegenwoordig alsmaar toe
en betreft een groot aantal
historische gebouwen, al dan niet
beschermd. Het lijkt evident dat
een pand met erfgoedwaarde moet
deelnemen aan de inspanning
om de broeikasgassenuitstoot
te verminderen, maar het lijkt
evenzeer vanzelfsprekend dat
de ingrepen rekening moeten
houden met de architecturale en
bouwkundige kenmerken van het
gebouw, opdat de aanpak niet
contraproductief zou zijn.
À travers des cas concrets
d’intervention sur du bâti
classé et non classé, cette
contribution brossera le cadre de
la problématique de ce paradoxe
et introduira les pistes pour
promouvoir une application de la
PEB compatible avec le patrimoine
architectural.
Aan de hand van concrete gevallen
van ingrepen aan beschermde
en niet-beschermde gebouwen
schetst deze bijdrage het kader
van de problematiek van deze
paradox en reikt ze pistes aan om
een toepassing van de EPB aan te
moedigen die verenigbaar zijn met
het architecturaal erfgoed.
23
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URBAN FORMS, TYPOLOGY AND
IMPROVING THE ENERGY EFFICIENCY
OF OLD BRUSSELS BUILDINGS
JULIEN BIGORGNE
ENGINEER, PARIS URBAN PLANNING AGENCY
THIS STUDY, COMMISSIONED BY THE BRUSSELS-CAPITAL REGION, STEPS OUTSIDE
THE WELL-TRODDEN SCOPE OF BUILDING-CENTRIC ENERGY STUDIES AND
INSTEAD TAKES A SYSTEMS-WIDE APPROACH. IT INCLUDES PARAMETERS USUALLY
IGNORED BY THIS TYPE OF WORK AND QUESTIONS PRACTICES CENTRED ON THE
APPLICATION OF STANDARDS.
This study, carried out at the
request of the Brussels Region,
was finalised in 2012. We were
asked to apply a method that we
had previously trialled in Paris to
evaluate the thermal capacities of
old buildings and to incorporate it
into the research currently underway regarding improvement of the
energy efficiency of Brussels’ architectural heritage. The full report
is available on the website of the
Monuments and Sites Department.
This presentation is a summary
of our work. I will firstly return to
the working methodology, as well
as the three scales of assessment
of the problem that we took into
account: region; city; and building.
I will not spend a lot of time on the
first as it was covered in the presentation on the EPB (see pp. 10-15).
I will then focus on issues related to
urban forms before coming to those
relating to buildings.
THE BROAD OUTLINE
OF THE METHODOLOGY
We are, in the medium term, facing
a dual challenge: supplies of energy
for urban systems, dependence
on which will have to be reduced,
and climate change, which means
reducing greenhouse gas emissions and adapting the territory to
this change. In order to respond to
these issues, Europe is proposing a
regulatory mechanism (“3x20”) up
to 2020. Application of this mechanism generally passes from the
European Union to the country or
region that then applies it directly
24 | Urban forms, typology and improving the energy efficiency of old Brussels buildings
to the building. This means that
the energy question is rarely considered at district level. However,
before working on a building, it
is important to consider its direct
environment, to think about the role
it plays in relation to its neighbours.
It is therefore this method that we
favoured in our approach.
There are two characteristics of
our work: it is exploratory and
illustrative. Exploratory, as it
opens up avenues that include
energy-related elements but which
are absent from the regulations.
In this way, we are trying to apply
a method that goes beyond simply taking the regulatory standards into account and enables us
to expand the research. It is also
illustrative as the purpose of this
Location of sites
Housing blocks used
for the calculation phases
Housing blocks that were the subject of
field visits and thermal analysis
(1A)
MUNICIPALITY OF SCHAERBEEK
and
St JOSSE-TEN-NOODE
“Housing block 18”
Rue GUSTAVE FUSS
Housing blocks preselected by
the Monuments and Sites Directorate
Building audited using the Energy Audit
Procedure method and the subject of field visits
MUNICIPALITY OF
WOLUWE St PIERRE
Town Hall quarter
“Housing block 4A and 4B”
Rue MARTIN LINDEKENS
MUNICIPALITY
OF ANDERLECHT
JARDIN: LA ROUE quarter
Plaine des Loisirs
MUNICIPALITY OF IXELLES
TENBOSCH quarter
“Housing block 2A”
Rue Américaine
MUNICIPALITY OF IXELLES
BERKENDAEL quarter
“Housing block 1A”
Rue de la Réforme
Fig. 1
Location of the sites studied (Produced with Brussels Urbis © CIRB).
mission is to present a method
that enables more extensive work
to be started on changes to the
energy performance of Brussels’
built heritage. A six-month long
project does not permit a large
quantity of work to be carried out.
Nevertheless, in order to have
a representative panel, we have
chosen ordinary architecture, i.e.
buildings that have been replicated
citywide over fairly large territories. These structures are not
always the work of architects. They
involve property development,
housing estates, average houses,
etc. from which we have attempted
to identify the problems associated
with renovations.
The raw material for our work was
made up of 21 “typical” blocks
pre-selected in agreement with the
Monuments and Sites Department;
11 buildings audited using the
Energy Audit Procedure method
by Centre Urbain; “infrared” thermal analysis carried out on the
selected sites; and research in the
archives of the municipalities concerned (fig. 1).
METHODOLOGICAL
CONSIDERATIONS
AT A REGIONAL SCALE
The energy issue must be thought
of as a series of “tiles”, or systems,
involving multiple parameters. The
occupant of a building doesn’t only
use energy for heating. He or she
also moves around: this is a question of transport. He or she has
a high or low income: these are
socio-economic questions. When
energy costs rise, certain items are
squeezed and others not. There are
therefore territorial inequalities
in terms of energy. Considering
energy dependence as a factor of
vulnerability means territorialising
energy consumption and, therefore, revealing the region’s already
existing or future inequalities.
However, this is not incorporated
within the regulations as, in short,
they assume that all buildings are
to be viewed in the same way and
that the same method and objective should therefore be applied to
them without distinction. However,
it appears that it’s not so simple.
The people in charge of planning,
and particularly energy planning,
must carry out the relatively complex
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process of overlapping the different
territorial “tiles”.
URBAN FORM: REDUCING
ENERGY CONSUMPTION
IS PRIMARILY A TERRITORIAL
CONCERN, NOT A
BUILDING-RELATED ONE
A building never exists as a separate
entity. It is always one element in a
larger-scale composition. As soon
as it is designed, it is envisaged
within and in relation to its environment (e.g. logic of sub-division,
rationale behind the “greening”
of urban spaces, etc.). The urban
form enables us to easily document
these elements relative to energy
consumption and to draw out elements for analysis. An examination
of building contiguity is interesting
in this regard. Historically, in order
to compensate for the absence of
efficient heating systems, buildings
were constructed adjoining each
other. By grouping houses together
in this way, heat loss surfaces were
reduced, thereby also proportionally reducing energy consumption.
In new, fully insulated buildings,
this fact is less important. However,
in old, non-insulated buildings,
contiguity was already being used
as an energy strategy. Any evaluation of the intrinsic qualities of a
building, prior to any work, must
take this essential fact into account.
Figure 2 illustrates the density of
buildings over time in a series
of seven housing blocks. A move
away from contiguity and greater
consumption of space can be seen.
One of the historical reasons for
this phenomenon is linked to the
definition of a town as a place of
exchanges, where the distances
needed to be short to facilitate
travel by foot or by horse. There
was a historical benefit in the town
being compact. This design is also
valid for buildings. The more compact they are, the more “liveable”
they become. Over time, with better heating systems and other
modes of transport, towns began
to spread out, consuming more
territory. In the diagram, this is
illustrated by a reversal of the ratio
of open to built-up areas. The consequences of these changes were
significant. In the 19th and 20th
centuries there was a reversal in
the amount of green spaces. This
fact must be taken into account
because when talking about urban
heat islands, urban microclimates and summer comfort, we
are dealing with an old and dense
city. This means that in winter the
energy consumption of a building
is, theoretically, less significant
than in peri-urban areas. However,
when a thermal audit is carried
out, the data used often to come
from peri-urban weather stations,
which can skew the initial calculations. For example, if the same
weather file is used for calculations in a zone in Woluwe-SaintPierre and for another area in the
old city centre, the errors will be
more pronounced in the calculations concerning the area within
the Pentagon (inner ring road) due
EXAMPLES OF BLOCK-LEVEL BUILDING DENSITIES
Grand Place
(Brussels)
Béguinage
(Brussels)
Pre Industrial Revolution
Tenbosch
(Ixelles)
Consolation
(Schaerbeek)
Berkendael
(Ixelles)
Late 19th century
Logis
(Woluwe-Saint-Pierre)
Bémel
(Woluwe-Saint-Pierre)
Interwar period
Post-war boom years
Fig. 2
Diagram of the historical evolution of building density. Over time, there has been a reversal of the ratio between built up and
open spaces. A rapid increase in the consumption of regional space can be seen (© Apur).
to the greater density. The differences can be as much as 10%.
An analysis of green spaces reveals
microclimate disparities, another
form of territorial inequality. Each
neighbourhood has a unique climate. The enclosed blocks from
the late 19th century, for example,
are urban creations where nighttime ventilation occurs naturally
during the summer. Figure 3 shows
a housing block the layout of which
produces a significant thermal
contrast between the green interior and the surfaced public space.
This has the advantage of creating
a stack effect, which is an excellent
alternative to air conditioning. The
natural ventilation inherent in the
building is assisted by the presence of landings and the resulting offsetting of levels (fig. 4). The
cellars also play a role in this phenomenon, as do the chimney flues.
These are often blocked off during
renovations to install controlled
mechanical ventilation (CMV),
which results in a loss of the ver-
Fig. 3
Top view of natural stack effect at
block scale. The difference between
how the ground is treated in the
central courtyard (entirely covered
in plants) and the public space
(fully surfaced) is likely to create a
pronounced thermal contrast which
initiates effective natural ventilation
(between the street and the yard).
The green areas have the capacity to
retain water, which evaporates during
heat waves (Produced with Brussels
Urbis © CIRB).
tical stack effect from the chimney
and its air vents. This can eventually make things unpleasant as if
the building is insulated, airtight
and a CMV system replaces the
chimney, this can create the ideal
conditions for problems to arise
during the summer months.
The design of the various types of
single-family dwellings is flexible. It can be seen that pressure
on land caused these spaces to
gradually shift and single-family
houses to transform into standard
apartments. The adaptability of
the design is interesting because,
in reality, it enables each resident’s energy consumption to be
reduced. Indeed, if it is possible to
move from a single-family house,
housing three or four people, to
three apartments; if there is a
financial advantage to this division
and, moreover, energy savings are
achieved, then the entire inner ring
becomes a focal point; this therefore results in a high demand for
housing. These are natural phe-
nomena and occur as a result of a
favourable market. The increased
density is based on a relatively
simple adaption of the design. The
stairwell, for example, can easily
incorporate the communal areas
as this space was, from the outset,
conceived in this way. However,
this transformation also produces problems: three apartments
potentially presenting damp rooms
on all floors. Yet, when renovating, dampness is a basic fact. Any
audit starts with the bathrooms as
hydrometry plays a central role.
MODIFICATION
OF SEQUENCES
Our work has led us to address
architectural heritage at an urban
scale, focusing on high-density developments, the quality of
spaces, etc. We are working on
the principle that, where renovation implies the partial or total
revision of building complexes, an
urban analysis provides elements
Fig. 4
Cross-sectional view of natural stack effect at the building scale depicted between
the yard and street. The landing adds a vertical component to the stack effect
(© Municipality of Ixelles).
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ONLINE
that can be used to determine the
extent of work possible. We have
compared sectors and sequences
of buildings. A perusal of the
archives and planning permission
records has enabled several facts
to be identified concerning these
sequences. I am going to focus on
three such sequences.
The first is located in Ixelles, in the
Berkendael quarter (fig. 5). Ordered
and symmetrical, it concerns a
housing development. The developer presumably used a catalogue
from which his customers selected
what they wanted. He arranged
it so that two similar buildings
would not appear side by side and
designed his sequence. He played
around somewhat with the symmetry, striving for consistency, in
the end creating an urban streetscape. However, an exception can
always be seen at each end, where
the buildings stand out in some
way so as to constitute urban landmarks. Here, if we take one of the
buildings and insulate it externally,
the streetscape will suffer. In this
case, the heritage issue is not at the
building scale but at street scale.
Our second example of a sequence
is situated on Rue Eeckelaers, in
Saint-Josse-ten-Noode (fig. 6).
Composed of mixed stock, it is
most likely the result of successive modifications. It is difficult to
give an opinion without seeing the
buildings up close. However, it can
be said that insulating one of these
buildings would not fundamentally
alter the appearance of the street.
These are typical examples from
the 19th century and are undoubtedly the subject of less attention
from a heritage point of view.
The third sequence concerns housing types from the 1950s, which, in
my opinion, offer some fairly interesting elements. Their construction
is still quite traditional while also
incorporating pre-fabricated components, such as the window frames.
In Woluwe-Saint-Pierre, these types
of houses offer a coherent sequence
with regard to the Town Hall, which
is part of a vista. While the buildings,
taken separately, do not arouse
much sympathy from a heritage
point of view, there is nevertheless
a coherent sequence. Modifying
any one of these buildings would
affect this coherence even though
the Town Hall is behind them. In
fact, its construction marks the
completion of the quarter and the
streetscape sequence in which it
is perfectly integrated. Conversely,
the sequence on Rue François Gay,
composed of older housing types
that feature heritage elements, is
mixed. Modification of an individual
building would not pose any particular problem here (fig. 7).
Urban form therefore enables
heritage to be viewed from the
perspective of sequences without
focusing on the building and its
details. Working at this scale also
involves examining the relationship between the buildings and
their immediate environment, and
considering their sustainability,
their vulnerability, and their ability
to cope with climate change.
The increase in energy prices and
the population explosion will tend
to bolster the process of densification of the existing city, particularly
for the inner ring with its consistent
land use availability. To what extent,
therefore, are the public authorities
likely to act? To what extent must
densification be managed? Urban
planning must facilitate this phenomenon while at the same time
protecting the intrinsic qualities
of existing fabrics, which means
giving special attention to existing green spaces (conservation,
removal of barriers, enhancement,
etc.), anticipating the emergence of
urban heat islands, identifying the
landscape qualities of architectural
and urban compositions, etc.
THE IMPLEMENTATION
OF ENERGY EFFICIENCY
MEASURES IN OLD
BUILDINGS
The selection offers a range of
housing types covering a period of
one hundred years, from the first
half of the 19th century up to the
post-war period. It involves ordinary architecture, the most common stock type, as well as a garden city. Here, I will address some
of the types, the use of materials
and their thermal conductivity.
We were surprised by the systematic use of brick and its persistence
over time along with the late presence of wooden floors, which certainly raise questions during renovations. As regards the thermal
conductivity of the walls, the target
- perhaps not overly ambitious was set at 0.4 (the bar is currently
0.2). In general, the buildings studied are not insulated and place us
within a classical analysis scheme.
The evolution of buildings
The first change to be noted is the
materials used. Throughout the
19th century, construction methods
remained traditional but the range
of materials, which were increasingly mass-produced, expanded
and enabled the style of architecture to become more diversified. In
this respect, the difference between
Neoclassicism (where the bricks are
rendered) and Eclecticism (where
the materials are exposed) is striking (see pp. 17). The limited use of
dense, and therefore conductive,
materials in eclectic architecture
resulted in a decline in the energy
efficiency of buildings (fig. 8)
Fig. 5
Berkendael quarter: Rue de la Réforme and Rue Van Driessche in Ixelles. The sequence is made up of pre-defined building
types “from a catalogue”. The use of symmetry creates an impression of diversity. A limited modification to the appearance of
a building impacts the streetscape (© Apur).
Mixed sequence
Fig. 6
Rue Eeckelaers in Saint-Josseten-Noode. This is a mixed
sequence with no particular logic
to the arrangement at street
scale. A limited modification to the
appearance of one building would
not impact the streetscape
(© Apur).
TOWN HALL QUARTER IN THE MUNICIPALITY OF WOLUWE-SAINT-PIERRE
1920-1935
1950-1960
1960-1965
1971 - Town Hall
Mixed sequence
ce
sequen
Mixed
ce
sequen
enous
Homog
Hall
Town
Mixed sequence
• Absence of unity;
• The façades do not have a
uniform appearance;
• No particular care required
for urban renovation.
Homogenous sequence
• The buildings are part of a coherent
sequence;
• Renovation of this complex precludes
any modification of the façades.
Town Hall, urban landmark
Fig. 7
More recent streetscapes, such as those from the 1950s or 1960s, often form successful streetscape compositions
(Diagram produced with Brussels Urbis © CIRB. Photos by the author).
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The same process can be seen
after the 1950s: improvements
in heating systems resulted in
a greater number of openings
in façades, in a search for ever
more light. In Neoclassical buildings, the proportion of openings
to solid wall is 1/3 to 2/3. In the
first quarter of the 20th century,
it reached 50/50. With technical advances, everything then
became possible: strip windows,
glass walls, etc. An examination
of the evolution of construction
techniques and their impact on
energy consumption shows a
widespread falling off in the postwar period (fig. 9).
There are numerous difficulties involved when renovating an
old building, depending on the
construction techniques used.
Modifying spaces is a complex
operation that can produce problems, most notably an increase in
thermal bridges. This risk arises
when working on reinforced concrete, beams, windowsills, lintels,
etc. Partial insulation of an area
can be dangerous; problems can
arise in places where the thermal
conductivity is greater. The less
standard the façade - for example, when there is a double wall the more serious are the thermal
bridge-related issues. Specific
solutions to address the problems inherent in these types of
buildings will have to be used for
renovations. In this regard, backyard annexes constitute a specific
problem. These outgrowths, made
from lightweight materials, pose
real problems in relation to density. Erected with no consistency
between them, these small structures generate thermal bridges in
all directions. They are generally
less dense than the main building.
Carrying out work on annexes has
a high potential for energy savings.
THERMAL CONDUCTIVITY OF OPAQUE STREET-FACING WALLS (W/M2.K)
Fig. 8
The thermal conductivity of opaque walls is a reflection of the construction
techniques used. These techniques are based on a constant: a solid load-bearing
wall, which explains the relative uniformity of the results and why they fall so
considerably short of the performance target formulated by the EPB (fixed at 0.4)
(© Apur).
RATE OF HEAT LOSS OF STREET-FACING FAÇADE
Neo-classical (33% openings)
Art nouveau (50% openings)
Walls (U = 1.8)
Bay windows (U = 4.65) Entrance (U = 3.06)
PERCENTAGE OF OPENINGS ON THE STREET-FACING FAÇADE
Increase in openings
Neo-classical:
1/3 openings
Art nouveau:
40% to 50% openings
Atypical
No particular logic
“Bel-étage” house
Fig. 9
Over time, the thermal properties of the buildings deteriorate (© Apur).
DEFINITION OF A
RENOVATION PROJECT OR
FINDING A BETTER BALANCE
Heritage requirements
Winter comfort (1)
(thermal resistance,
efficiency of heating and
ventilation systems, etc.)
Winter comfort is often the sine qua
non of renovation. This is the criterion that takes precedence in the
standard calculations. However, the
measures taken for winter comfort
must not counter summer comfort.
For example, interior insulation of
solid walls may compromise the
benefits that they provide in the summer. In the same vein, it is necessary
to anticipate the problems that may
be created by the renovation work.
Furthermore, there is also one
essential element missing in the
reasoning applied to renovations:
the behaviour of users. This means
The audit techniques
The audit of the eleven buildings
was carried out by Centre Urbain
using PAE (Energy Audit Procedure)
software, currently used by auditing firms. It is interesting to be
able to analyse and critique this
PAE method and the results that it
provides. The main point is the difference between the reality of the
building’s occupation and what the
calculation takes into considera-
Summer comfort (2)
(creation of masks,
boosting of inertia)
Change in climate
(climate change modifies
the relationship between
heating and cooling needs)
Double-glazing
(U = 1.63)
135
200
Behaviour of users
and occupation strategies
(set-point temp., buffer spaces)
Renovation project
Urban heat island
Putting the cost of the
operation into perspective with
regard to the expected gains in
energy savings
Legend
Criterion systematically absent
Criterion not properly taken into account
Criterion taken into account in renovation operations
(1) The sole criterion actually addressed by the EPB regulation
(2) Not sufficiently taken into account by the EPB regulation
understanding that people’s behaviour is unpredictable and does
not follow a pattern. The sociology
of the building must be taken into
account when dealing with a renova-
tion. Without the residents’ support,
the energy saving objectives being
sought will remain out of reach.
tion. A factor of 2, or indeed often
far higher, is often diagnosed for
a single-family house. The occupancy scenario - how the rooms
are actually used - is a decisive
factor, even more so if the renovation is intended to be cost effective. By over-estimating the costs
of renovation, the payback periods
calculated become too long. In
most of the cases examined, the
PAE software calculates a payback
period that exceeds the lifespan
of the renovation solutions, and
this is in the best-case scenarios.
These findings can be interpreted
in a number of ways:
- The required level (U value) is too
high;
- The solutions envisaged are not
suited to the consumption profiles of old buildings; or
- The software is not appropriate
for energy audits of old buildings.
Unit cost (€/m2)
Insulation
(U = 0.49)
Existing problems
and anticipation
of future problems
Price of gas
(€/kWh)
0.065
Price of gas
(€/kWh)
0.013
Interest rate
3%
Interest rate
3%
Inflation
2%
Inflation
2%
Surface area (m2)
Investment (€)
Lifetime of
investment
(years)
Payback period
(years)
Updated payback
period (years)
Payback period
(years)
Updated payback
period (years)
Front façade
34.93
92.66
30
39
46
20
23
Rear façade
29.43
92.66
30
39
46
20
23
Annex
19.75
61.32
30
19
22
9
11
Single-glazed window
7.09
29.26
20
35
38
14
15
Fig. 10
Example of a PAE audit, carried out on a neoclassical building. The payback periods calculated are long. If the economic actors do
not see any financial benefit in undertaking energy efficiency works, the overall objective of a 20% reduction does not seem to be
achievable. There is a high chance of the grants being misappropriated and fuelling a windfall effect (© Centre Urbain).
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Many materials currently used
in renovations are not long-lasting and have to be replaced after
ten or fifteen years. Unless the
systems are used correctly and
continuously - which is rare, as
doing so restricts how the building in used - 50 kWh will not be
achieved in old buildings. There
are many examples of landlords
who are paying building management fees for 50 kWh, which ultimately reaches 150 kWh. Was the
money invested in the right place?
Nothing is less certain. If the meter
is showing 150 kWh instead of 50, it
means there is a problem. Perfect
examples can always be found.
However, the question relates to
the most frequently encountered
situations and what happens in
ordinary buildings.
Fig. 11
External insulation in rear courtyards does not, in principle, cause problems
(photo by author).
LA ROUE GARDEN CITY: VARIED BUILDING TYPES REQUIRING DIFFERENT RENOVATION SOLUTIONS
Municipality of Anderlecht
“La Roue” Garden City
Network of public spaces:
hierarchy and composition
Neighbourhood perimeter
Network hierarchy
Transit route
Link road between quarters
Local access road
Private alley
Urban composition
Local square
Square within a housing block
Public green space
EXTERNAL INSULATION:
USE WITH CARE
External thermal insulation means
revising existing façades. It is possible, indeed even recommended,
for annexes and the rear façades
of buildings, where it does not, in
principle, pose any problem (fig. 11).
It can be applied to street-facing
façades under certain conditions:
buildings with significant damage
or with façades that were redesigned during unscrupulous restorations. Buildings that are part of
a mixed streetscape must be considered on a case-by-case basis. It
may be possible to insulate some
of them externally but not others.
Buildings that are part of heritage
streetscape sequences require a
more subtle approach, again on
a case-by-case basis. The highly
complex example of La Roue is
interesting in more ways than one
(fig. 12): it is an estate that has
changed a lot. We have had the
opportunity of looking at some
width of roadway
(parcel to parcel)
width of roadway
(building to building)
Plaine des loisirs” (1921): typical building
façades in La Roue Garden City.
Rue des Citoyens (1907): a homogenous
sequence that should be preserved.
Drawing of “Plaine des Loisirs”
at the La Roue metro station.
Experimental project (1921): a zone that could be
returned to its vocation using energy saving techniques.
Fig. 12
La Roue in Anderlecht. The oldest historical sequences (1907) still standing
necessitate preservation of the façades as they currently stand. There is a
particular symbolic dimension to “Plaine des loisirs”, which has undergone
vernacular modifications (polychrome render, etc.). Any future renovation
solutions will have to take heritage like this into account. Studies need to be
carried out to determine possible changes (diagram produced with Brussels Urbis
© CIRB. Photos by the author).
sequences from this development:
some of them are of historical
importance and external insulation must be prohibited. However,
certain types are suitable, as they
have changed a great deal. It would
be necessary to study the details of
these changes; to see how people
have adapted the spaces, which is
acceptable with such changes; as
well as how they should be managed, etc. Insulating renders could
offer a solution. Nevertheless,
there is no universal technical
solution applicable everywhere at
all times. Certain zones such as
the “experimental project” in La
Roue, a former technology showcase, could be returned to its original vocation through the use of
innovative renovation solutions.
Clearly, such an approach requires
moving away from the regulatory
mindset.
INTERIOR INSULATION:
A SOLUTION THAT CAN
CREATE PROBLEMS
Interior insulation does not
require planning permission. The
absence of any requirement for
permission gives the impression
that the technique belongs to
the realm of basic DIY. In reality,
it is the most complex types of
insulation as it can create a lot of
problems, especially in old buildings. This doesn’t mean that it
shouldn’t be used, only that great
care should be taken when it is.
We have gained substantial experience in Paris with the use of brick,
both in terms of insulating it and
learning about its inherent problems. We have noticed the harmful effects of interior insulation on
numerous timber frames. When
the structure is affected and the
building becomes unhealthy, the
only solution is demolition/recon-
struction. The advantage and disadvantage of using brick is that it
retains dampness well. It may take
five or ten years, or even longer, for
problems to appear. Interior insulation often prevents the dampness
stored by the bricks from drying
out. This is what we often encounter in west/south-west facing
walls, pounded by rain, or in walls
covered with glazed bricks, which
are highly permeable to damp.
CONCLUSION
If we want to achieve the standard
of U= 0.4 or 0.2, highly insulating materials such as polystyrene
or rockwool will have to be used.
However, solutions such as these
can be counter-productive over the
long term. By conceding that no
attempt will be made to achieve
the standard, we open up the possibility of using materials that are
compatible with old structures
(such as hemp concrete, cellular
concrete, lime renders, cork, etc.)
whose thermal properties are,
today, almost on a par with polystyrene.
Another area worthy of investment
is planning regulations, which
have a role to play in guiding the
phenomenon of densification. This
involves, among other things, the
preservation of certain interior
green spaces to prevent the emergence of urban heat islands.
We have tried, on certain projects,
to aim for a performance of 0.8 and
not 0.4. Meter readings indicate a
building now using 80 kWh. The
cold wall effect has been eliminated and the residents no longer
suffer from a lack of comfort. They
are therefore using less heating. Once again, it involves considering the actual situation and
actual behaviour of the residents.
Nowadays, there are other materials besides polystyrene which,
admittedly, are less efficient in
theory, but with which interesting
things are being done in practice.
To conclude, I want to return to
some key points from the study.
Firstly, it would be interesting to
territorialise energy dependence
so as to be able to prioritise energy
ambitions at a regional scale. It is
not possible to be efficient everywhere; choices must therefore be
made, especially since budgets
are, in general, limited.
As regards buildings in the strict
sense, improving knowledge about
the existing stock and their specific
features requires the collection of
a large amount of statistical data
on energy consumption. This initial step will also help to refocus
the level of public subsidies for the
performance required in old buildings and validate the effectiveness
of work by means of “before and
after” comparisons.
Finally, the question of capitalising
on feedback arises: knowing what
has been done, what works, what
doesn’t work, etc. over the long term
is essential in order to assess the
actions taken and decisions made.
The dogma that states “a good building is one that is airtight and thermally insulated” is not a valid one.
Greater subtlety is required. There
must be room for observation and
experimentation. Help must be provided to improve the qualifications
of project managers and promote
the smart approach to buildings and
renovations.
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Formes urbaines, typologie
et amélioration des performances
énergétiques du bâti ancien
bruxellois
Stadsvormen, typologie
en verbetering van de
energieprestaties van oude
Brusselse gebouwen
The complete study is available
on the websites of the Direction
des Monuments et des Sites
and APUR:
À la demande de la Région de
Bruxelles-Capitale, l’Apur a réalisé
une étude sur la performance
énergétique des bâtiments
de logements anciens. Cette
étude aborde les perspectives
d’économies d’énergie dans le bâti
ancien bruxellois sur la base d’un
échantillon de bâtiments audités.
Au-delà du commentaire portant
sur les bâtiments, la démarche
propose également de considérer
la question de la forme urbaine
et de regarder en quoi cette
dernière impacte, elle aussi, les
consommations d’énergie du bâti.
Enfin la question de la vulnérabilité
énergétique du territoire
régional est abordée, ainsi qu’un
questionnement sur la nécessaire
cohérence entre les leviers qui
relèvent d’une part du territoire
régional, d’autre part des quartiers
et, enfin, du bâtiment.
Op verzoek van het Brussels
Hoofdstedelijk Gewest
realiseerde APUR een studie
over de energieprestatie
van oude woningen. Deze
studie buigt zich over de
energiebesparingsvooruitzichten
voor oude Brusselse gebouwen
op basis van een audit van een
staal van de gebouwen. Naast
opmerkingen over de gebouwen
stelt de studie voor om de
vorm van het stadsweefsel in
aanmerking te nemen en na te
gaan hoe die ook een impact
heeft op het energieverbruik
van de gebouwen. Tot slot
wordt aandacht besteed aan
de energiekwetsbaarheid van
het gewestelijk grondgebied en
worden vragen gesteld over de
noodzakelijke coherentie tussen
de hefbomen die enerzijds
afhankelijk zijn van het gewestelijk
grondgebied en anderzijds van
de wijken en ten slotte van het
gebouw zelf.
http://bit.ly/1CMqiqM
http://bit.ly/1UDw6Am
35
ONLINE
THE LISTED HOUSES OF THE LE LOGIS
AND FLORÉAL GARDEN CITIES
ADAPTATIONS TO CURRENT ENERGY AND
COMFORT NEEDS
GUIDO STEGEN
ARCHITECT, ARCHITECTURAL FIRM ARSIS BVBA
LE LOGIS AND FLORÉAL IS A GARDEN CITY THAT SHOWS US AN INTERESTING
INSTRUMENT FOR COMBINING CULTURAL VALUES AND ENERGY NEEDS.
TWO ASPECTS WILL BE ADDRESSED HERE: THE MANAGEMENT PLAN AND
THE FINANCIAL ASPECT OF THE ENERGY SAVING MEASURES EMPLOYED.
OPTIMISING THE ENERGY
PERFORMANCE OF LISTED
HERITAGE: AN EXERCISE
WITH IMPACT
The title of this contribution is:
“Adaptations to current energy
and comfort needs”. The word
“needs” instead of “standards” has
been chosen deliberately. Through
energy measures that conform
with heritage, the Beheersplan voor
Erfgoed (Heritage Management
Plan) of the Le Logis and Floréal
garden city is striving to fulfil the
need for efficient energy consumption in the most optimal manner.
“Optimising” is the key word here:
it is an exercise in balancing the
potentially conflicting interests
of the heritage, cost price and
performance. The investment to
energy performance ratio is key to
ensuring maximum energy savings
within a limited time frame (20 to
25 years). Within a limited amount
of time, the financial means must
be found and invested in order to
improve the energy performance
in the majority of houses. Only
then can the largest global energy
savings be realised within this time
frame.
The Le Logis and Floréal garden
city is large. It is a complex of two
garden cities, situated in section of
the Brussels periphery built up in
the 20th century, approximately six
to seven kilometres from the city
centre. There are currently approximately 540,000 residences in the
Brussels-Capital Region, of which
(only) ± 8% are social housing
36 | The listed houses of the Le Logis and Floréal garden cities
residences (fig. 1). Between 1920
and 1940, approximately 125,000
houses were built in the Brussels
municipalities, 9,000 of which were
social housing residences. 4,000 of
these have fewer than three floors,
including the Le Logis and Floréal
listed houses. With these figures,
I am trying to give an idea of the
impact the conclusions of the
management plan can have. About
4,000 social housing residences in
the Brussels-Capital Region are
structurally and technically comparable to the Le Logis and Floréal
listed houses, not to mention the
non-social housing residences
of the same type (approximately
40,000).
Figure 2 shows the houses that,
in the government decisions of
Residences in the Brussels-Capital Region
As of January 2013
540,000 residences
of which
39,400 social housing residences (= 7.3%)
3,500 social housing residences managed
by a social rental office
42,900 total, i.e. 7.94%
‹ 3 lev.
3 to 6 lev.
› 3 lev.
Total
LE LOGIS AND FLORÉAL:
A MATTER OF COHERENCE
Residences in the Brussels-Capital Region
As of January 2013
125,000 residences (estimated)
of which
9,000 social housing residences (1921-1937)
of which
4,000 with fewer than 3 floors
of which
25% in the garden city Le Logis & Floréal
Evolution of the construction of social housing
residences in the Brussels-Capital Region
Fig. 1
Houses in the Brussels-Capital Region. (Guido Stegen, based on the
“Inventaris van de Volkswoningen te Brussel” (Inventory of Public Housing
in Brussels), Sint-Lukaswerkgemeenschap, Lagrou E., Sept 1985).
1,000 single-family residences
30 duplex houses (60 residences)
2 apartment buildings
- on a site of 57.32 ha
- 1,060 sheltered housing units
- dating from before 1940
- 1/4 private
- 3/4 statutory social housing
residences
The whole garden city complex consists of two cooperatives, Le Logis
and Floréal. Each has a centre characterised by high-rise buildings and
central functions: offices, shops
and even a theatre in Le Logis. The
whole encompasses four entities
characterised by the colour of the
exterior woodwork. This is yellow
for Floréal. Three entities are
present in Le Logis: green/white,
off-white and green/black.
The garden cities were built
according to designs by four individuals. These were Louis Van
der Swaelmen who designed the
spatial structure of the neighbourhoods, and the design plan;
and three architects: Jean-Jules
Eggericx, Raymond Moenaert and
Lucien François. More than 90% of
the houses were built according to
Eggericx’s designs; Moenaert and
François designed approximately
one hundred houses, all in Floréal.
Within the site (which is marked
with a black line) many other
buildings can be found, including
two high-rise apartment buildings
which are listed as monuments
but are not part of the management plan.
The 1,060 dwellings were constructed across six sites and in 16
design phases (or dossiers). The
varying procurements, prices and
contractors resulted in diversity
in techniques and details to the
on-site phases. When drawing up
the management plan, we are confronted with this diversity; we must
ascertain whether this is a coincidental diversity with no importance
for further conservation or a conceptual diversity which must be
studied and maintained.
Although built in the same way,
not all listed houses are managed
The garden cities comprise a large,
cohesive whole. For decades people
Source: in situ registrations by Arsis, original plans, old postcards
Graphic support: Urbis top
Fig. 2
The garden cities are listed as an entirety by the Government decision of the
Brussels-Capital Region Government of 15 February 2001 and 6 December 2007
(© ARSIS).
15/02/2001 and 06/12/20071, are
listed as part of the garden cities “as a
whole”. Only the so-called outer shell
of these houses is listed: façades,
roofs, exterior woodwork, etc.; in
short, everything that is visible from
the outside. In figure 2, the singlefamily dwellings are marked in red,
duplexes in orange and low apartment buildings in blue.
as social housing residences2; one
quarter is managed privately and
three quarters are managed by
social housing companies.
37
Spatial coherence (neighbourhoods),
by acquiring a spatial continuity
arranged in a hierarchy (avenues,
streets, paths, squares, etc.) and
through colour themes.
The colours of the exterior joinery are linked to the neighbourhoods.
Front door types and the way the houses are arranged in rows are linked to the open space.
ONLINE
Groups of houses, composed through
connection, mirroring, rotation,
etc., of the offer of house types, and
through adjustment of the site relief.
66 house types as originally designed,
with a varying programme, and
compiled using the elements of local
heritage.
Elements of local heritage, compiled
starting with standardised type
details, and with continuous windows
with a ratio of √2.
Standardised type details
Fig. 3
The composition of a large whole (© ARSIS).
have been trying to determine just
exactly what the cement is that
makes a cohesive whole. The usual
way of obtaining large wholes is
“bottom up”. This means that construction is executed from one level
to the next using standard details
(doors, windows, roof shapes, etc.).
These are then brought together in
larger scale design decisions, such
as façades, houses, etc. These are
grouped together in combinations
of houses or groups of houses. The
effect of pure bottom-up grouping
is that many houses are identical
and there is a lack of diversity and
recognisability.
In the case of Le Logis - Floréal,
various pioneering ideas have
resulted in:
• diversity which is neither arbitrary nor chaotic;
• unity without similarity or boredom.
Coherence comes from complexity,
which essentially boils down to “making connections”. The garden city features not only connections between
successive scale levels (detail >
elements > type of house > group
of houses > neighbourhood level)
but also between non-successive
scale levels (for example: elements
> groups of houses, or type of house
> neighbourhood level (fig. 3)).
Since the designers did not simply
link elements to types of houses,
the management plan provides
a distinction in the description
of the composition logic between:
1) elements inherent to the type of
house; and 2) elements which are
not inherent to the type of house.
All of this is explained in one of the
volumes of the management plan,
namely “T04. Unity in diversity”. The
fact that some elements could not
simply (1/1) be linked to a type of
house is the reason why the tables
of houses (T01), the thematic maps
(P03), and the global construction
plans (P11, P12, P13 and P21) have
been included in the management
plan. These documents localise
elements not inherent to the type of
house.
The tight, complex coherence leads
to the feeling that the garden city
is the result of one large, unique
design, notwithstanding the building of 1,000 houses over a period
of 15 years. Standardisation in the
production and design process was
absolutely essential. Only a limited
number of basic elements were
used to create one large, coherent,
organic whole while avoiding
repetition, boredom and a lack of
wholes of
connected
open spaces
rows of houses
house types
local heritage
construction
details
Fig. 4
The coherence in the larger whole of the garden city originates from the complexity
of the composition, more specifically the arrangement of the elements and houses
on different scale levels
personality. The modernists called
this quality: “unité dans la diversité, diversité dans l’unité”- unity in
diversity, diversity in unity.
THE MANAGEMENT PLAN
Recently, the Brussels legislation
regarding urban development has
begun to allow large groupings of
buildings belonging to different
owners to be managed by heritage
management plans. Thanks to the
management plan, most buildings
are exempt from building permits and subsidies are easier to
obtain. The management plan for
Le Logis and Floréal was the first
in the new legal urban development framework in Brussels; the
plan was approved by the Brussels
Government on 23/05/2014 and
published in the Belgian Official
Gazette on 01/09/2014. The first
steps towards the management
plan were taken back in 1999, i.e.
before the heritage protection act.
The composition principles (“unity
in diversity, diversity in unity”) had
to be unravelled, technical details
measured and the diversity of the
local heritage mapped out. Also the
form and content of a management
plan as an instrument still had to be
first invented and then refined.
In 2000, an inventory was made
of the 1,060 listed houses. In an
inventory, the condition of the
houses is assessed and documented with the intention of applying the heritage protection act. The
inventory allows the nature of the
works and subsidies to be determined as well as any violations of
the heritage protection act.
In 2001, the houses and the design
of their surroundings as a whole
were both listed. In the period
2006-2008, the first-generation
documents from 2000-2002 were
complemented with new themes
and detail relating to built-up
elements in the surroundings.
Finally, in May 2014 the official
management plan became a reality.
The management plan describes
the permitted works both in text
and with drawings:
• to the outer shell of the dwellings: the façades, exterior woodwork, roofs and garages;
• in the surroundings: the garden
sheds, parapets and banisters,
retaining walls and technical
installations (energy, water, telephone, etc.).
The objectives of the management
plan are:
• to preserve the principle of “unity
in diversity, diversity in unity”;
• to cater to contemporary needs
(thermal, acoustic, hygiene)
without damaging the heritage
value of the buildings;
• to avoid the usual permission
procedures for the above-mentioned works.
Two exceptions remain subject to
permission: insulating the façades
and treating damp in walls and
façades. An audit demonstrating
that the intended works are
effective, of priority and without
any adverse side effects for the
building and its inhabitants must be
carried out prior to these works
being undertaken. The previous
intervention (pp. 24-34), by Julien
Bigorgne, clearly demonstrated
that damp problems only become
worse if treated incorrectly.
The authorities act as coaches for
the management plan. Specifically,
this means:
• informing, documenting
and raising awareness
regarding the heritage;
• providing well-researched
solutions;
• granting subsidies.
The management plan functions in
relation to two other concepts, and
distinguishes itself from these:
• The reference situation describes
the technical, historical and artistic
individuality and the coherence of
the heritage, including the adaptations to current needs.
• The management plan for heritage
describes all of the possibilities
permitted to realise the reference
situation.
• The projects are the descriptions
of the specific works owners are
carrying out on their property.
39
ONLINE
The management plan, drawn up
for the Le Logis and Floréal garden
cities and approved by the Brussels
Government, contains 13 volumes:
seven textbooks (T00 to T06); six
books containing drawings (P01 to
P20); and four large overview plans
of the neighbourhoods.
T00: Management plan manual
T01: Table of the listed houses
T02: Technical provisions
T03: Research reports
T04: Unity in diversity
T05: Adaptations to the current
needs
T06: Inventory - instructions
P01: Catalogue of local heritage
P02: Construction details
P03: Theme maps
PO4: A4 documents from plans
P11, P12, P13, P21
P10: House types, Le Logis
P20: House types, Floréal
P11, P12, P13, P21: Built-up
areas of the houses in
the neighbourhoods
These documents form one whole,
as do the garden cities themselves.
They refer to each other and thus
themselves describe the principle of “unity in diversity, diversity
in unity”. The volumes detailing
types of houses (P10 and P20), for
example, show which windows are
present in a certain type of house.
The catalogue for local heritage
(P01) shows these windows and
refers to the details from which
the windows have been constructed. The construction details
(P02) show these details, etc. The
texts and drawings describe both
the original and present condition
as well as which adaptations are
permitted. This is how the management plan works: it is based
on an interaction between the various volumes, so readers will know
(starting from the specifications
and detailed plans) which specific
works are permitted in any specific place, and at whichever scale:
house, element, detail, etc.
ADAPTATIONS TO THE CURRENT
NEEDS WITH REGARD TO INTERIOR CLIMATE AND ENERGY
The origin of the energy
section of the management
plan
21/02/2013: Amendment by
the Brussels-Capital Region
regarding EPB
• Centre d’Étude et de Recherche et
d’Action en Architecture (CERAA)
2009-2011: Audit énergétique des
maisons classées des cités jardins
Le Logis et Floréal
• Atelier parisien d’urbanisme
(APUR)
2013: Amélioration des
performances énergétiques du
bâti ancien de la Région Bruxelles
Capitale. Study requested by the
Brussels-Capital Region
• CENERGIE
April-May 2014: Energy audit of
two Le Logis houses (as described
in the management plan) in
compliance with the energy and
comfort measures provided in
the Heritage Management Plan
The energy study and audit performed by CERAA in 2009-2011
used the Energy Performance
of Buildings (EPB) standard as a
starting point to examine whether
or not it could be reconciled with
the heritage and global3 budget
planning. This was not the case,
and it remained difficult to decide
which measures should take
precedence in a joint heritage and
energy policy, and which would be
both technically and financially (in
terms of both financing and subsidies) sustainable for the entire
neighbourhood.
The measures in the management
plan regarding comfort in interior
climate and energy performance
cannot be separated from a development in legislation and studies
which preceded the final approval
of the management plan.
• Energy Performance and Indoor
climate (EPB)
12/12/2002: European Directive
21/12/2007: Government
decision of the Brussels-Capital
Region regarding EPB
19/05/2010: Adaptation
European Directive
Dealing with the aspect of energy
savings in a purely performance-based manner or using
standard solutions for energy savings is not feasible: the design of
the garden city, its occupancy, its
history and its fame are aspects
of sustainability. For the energy
transition in Le Logis-Floréal, the
proposed solutions must take all
criteria relating to the conservation of the heritage into account.
These residences were originally
fitted with numerous devices and
Volume T05 highlights how the
permitted works seek meet the
current needs regarding energy,
comfort, acoustics and safety. It
forms connections between those
themes and also points out certain
contradictions between the objectives of these various themes to
the owners. In volume T05, the relevant application of certain works
is explained. The management
plan expects and requires:
• priorities to be determined
according to the funds available;
• the works to be executed in the
correct order;
• a realisation that gains in a certain
area can mean losses in another
area;
• choices to be made which are
adapted to the specific house a
person is living in and envisaging
the house after the works have
been completed;
• that the potential energy savings resulting from simple and
small habits and improvements
compared to those requiring
large investments should not be
underestimated.
innovations which offered a certain level of comfort against the
cold (e.g. locks and lay-out of the
rooms), overheating (e.g. shutters,
thermal inertia), etc. However,
due to a rise in energy costs there
is a risk of the residences being
heated, used and modified incorrectly. The problems which may
arise can be detrimental to both
the conservation of the heritage
and the health and comfort of the
residents.
Cenergie’s energy study and audit
was performed in compliance with
the management plan in order
to be eligible for regional subsidies. The starting point of this
approach was the improvements
regarding energy and interior climate provided for in the management plan. It then examined the
energy performance of each specific case4; based on this, the most
efficient measures are suggested.
Jonathan Fronhoffs from Cenergie
tells us more about this study in
his contribution (pp. 48-53).
Limitation of energy needs
with an emphasis on
improving comfort
In the Trias Energetica, it is assumed
that a sustainable building first limits its energy needs and, secondly,
makes use of renewable energy
sources instead of wasting fossil
fuels. The first measure is usually realised by insulating the outer
shell. Not all types of insulation
used on the outer shell are equally
efficient; the management plan
requests that this efficiency - with
regard to finances and energy - be
taken into account in order for a project to be granted a subsidy.
However, limiting energy needs
can also be achieved in ways
other than insulating the outer
shell, namely by creating a feeling of comfort for the residents at
a lower room temperature. It is,
after all, widely known that feeling
comfortable is influenced not only
by the temperature in the room
but also by drafts, humidity and
air quality. This is called the interior climate. By avoiding drafts,
humidity and cold surfaces, a
feeling of comfort can be created
at a lower room temperature.
In this way, less energy is lost
through the outer shell through
conduction, convection and air
leaks. In the audit style developed
by Cenergie it is assumed that
the average (day and night) room
temperature can drop by 1°C after
comfort has been restored. This
alone produces a considerable
saving, without loss of comfort.
We are all familiar with the examples of convection heaters and the
cosy heat they emit when it is cold,
or the pleasant feeling of a cold,
sunny day.
Measures which benefit comfort
and health are also beneficial to
energy savings, but saving energy
is not necessarily beneficial to
comfort and health. Insulating
the outer shell produces generally acceptable, calculable energy
savings. Solving comfort deficiencies influences the energy
bill indirectly; the energy loss
decreases because the difference
between the inside and outside
temperature is decreased. Air
temperature is a decisive factor
in the influence of the thermal
resistance of the outer shell on
the energy bill. If the room air
temperature can be lowered, the
efficiency of insulating the outer
shell decreases.
Insulating the outer shell and
interior climate comfort are very
closely connected, but nonetheless clearly distinguishable.
They influence one another, but
require different actions. The
former mesures are often less
heritage-friendly than the latter; therefore the management
plan characterises the measures
according to this distinction.
In short, the management plan
provides the following measures to
limit the energy need, in descending order of priority, by:
• improving comfort (interior micro
climates, humidity, etc.);
• improving the airtightness of the
shell;
• insulating the shell (roofs,
floors above non-heated spaces,
façades);
• improving the performance of
equipment (lighting, heating,
sanitary fittings, hot water).
These measures have been refined
into a dozen specific measures,
listed in the figures 5a and 5b:
• from 1.1 to 1.5: comfort and
hygiene
• from 2.1 to 2.6: insulating the
shell
• 5: energy-efficiency of the techniques
This appendix also summarises all
the works from the technical provisions (T02) which contribute to
one or more of the aforementioned
measures, and demonstrates the
connections between them.
Lastly, figure 6 shows the location
of the various measures using the
façades and design plans of one
type of house (LLw_D).
The energy results
of the heritage-conformance
measures
Both as an example and for
research purposes, two specific houses were examined in
the energy audit to ascertain
the exact energy performance of
specific measures (see pp. 48-53).
Clearly, two houses is a very
small sample to draw conclusions from, but for the time being
this small study gives us an
41
B1.1
Restoring
crumbling
decorative
plaster
Herstellen van
afgebrokkelde
sierpleister
B1.2
Herstellen van
barsten
in decorative
de sierpleister
Restoring
cracks
in the
plaster
B1.3
Aanbrengen
van een
nieuwe
speciale eindlaag van
Applying
a special
new
end layer
of
dedecorative
sierpleister plaster
isolatie van
de plastered
bepleisterde
gevels
Thermische
Thermal
insulation
of the
façades
B1.4
B1.5
B2
B4
Herstellen
vanexisting
een bestaande
schouw type B
Repair
of an
type B hearth
B5.5.1
Repair
of an
type E hearth
Herstellen
vanexisting
een bestaande
schouw type E
B6.1
Herstelling
van deurdorpels
Repair of door
thresholds
B6.2
Herstellen
van vensterbanken
Repair
of window
sills
B7.1.3
Thermal
insulation
at the
of van de
Thermische
isolatie aan
de interior
binnenkant
the
cold bridgeaan
by betonnen
concrete canopies
koudebruggen
luifels.
C2.2
Zinken
dakbedekking
- Alle
dichtingswerken
Zinc
roof
cladding - All
sealing
works
C2.3
Bituminous
sealing op
on beton
concrete
Bitumineuseroof
dakdichting
- Alle
-dichtingswerken.
All sealing works
C2.4
Kroonlijsten
engutters
dakgoten
- alle
dichtingswerken
Cornices
and
- All
sealing
works
C1.4.1
Insulation
works
slopingdaken,
roofs,ter gelegenheid
Isolatiewerken
vanon
hellende
for
purpose
works
around the exterior
vanthe
werken
langsofde
buitenkant.
C3.2.4
C4.6
D1.2.2
D1.2.3
D1.2.4
D1.2.5
D1.3.3
D1.3.4
2.6 Saneren
van vochtige
Decontamination
muren
enwalls
vloeren
of damp
2.5 Isolatie
vanofde
Insulation
voordeuren
the front doors
2.4 De
beglazing
de
Glazing
of thevan
exterior
buitenschrijnwerkerij
woodwork
2.3 De daken
Roofs
2.2 Vloeren
boven niet
Floors above
verwarmde
non-heatedruimtes
spaces
2.1 De gevelmuren
Façade walls
Thermische
isolatie van
de cold
koudebruggen
Thermal
insulation
of the
bridges aan de
at
the interior
bow windows
(loggias)
binnenkant
vanof
dethe
bow-windows
(loggia's).
C2.1
C1.4.2
1.5 Sanering
van vochtige
Decontamination
of
muren
en vloeren
damp walls
and floors
Thermal
insulation
at the
of van de
Thermische
isolatie aan
de interior
binnenkant
the
cold bridgeaan
by betonnen
concrete cornices
koudebruggen
kroonlijsten.
Thermal
insulation
of the
of van de bowThermische
isolatie van
de exterior
buitenzijde
the
bow windows
windows
(loggia's).(loggias)
Thermal
insulation
of the
of the
Thermische
isolatie van
de interior
binnenzijde
vanwalls
de
under
windows
of thevan
bow
dewindows
bow-windows.
muren the
onder
de vensters
Pannenbedekking
- Alle
dichtingswerken
Tile
roof cladding van
- Alldaken
sealing
works
B7.3.4
1.4 Zomerconfort
Summer comfort
Drip
moulding
on plasteredgevels - Restitutie &
Druiplijsten
op bepleisterde
façades
- Restitution & Restoration
Restauratie
B5.2.1
B7.3.3
1.3 Wegwerken
Eliminating van
cold
koudebruggen
bridges
Black
layeraan
at the
base van
of de gevels Zwarteprotective
beschermlaag
de basis
the
façades&- herstelling
Maintenance and repair
Onderhoud
Herstellen
vanexisting
een bestaande
schouw type A
Repair
of an
type A hearth
B7.3.2
5.
5.
Other
Andere
Thermal
insulation
at the
Thermische
isolatie aan
de interior
binnenzijde van de
of
the reveal
the
façade openings
dagkanten
vanofde
gevelopeningen
B5.1.1
B7.2.3
1.2 Luchtdichtheid
Air-tightness ofvan de
the exterior woodwork
Articles provided for in the technical specifications
Artikels voorzien in(book
de technische
voorschriften
T02)
(boek T02)
1.1 Compartimentering
van
Compartmentalisation
de
ruimtes
of the
spaces
Huidige
behoeften
Current
needs
Hygrothermal measures
for
2. Energy savingdoor
by working
1.1.Hygrothermische
maatregelen
2. Energiebesparing
werken aan
comfort
and
health
onde
the
outer shell
voor comfort en gezondheid
buitenschil
5.1 Performantie
Performancevan
of de
infrastructuur
infrastructureen
and
equipment
uitrusting
ONLINE
Insulation
works
slopingdaken,
roofs,ter gelegenheid
Isolatiewerken
vanon
hellende
for
purpose
works
around the interior
vanthe
werken
langsofde
binnenkant.
Placing
roof window
Plaatseninsulated
van een geïsoleerd
dakvlakvenster - met
-zonnewering
with sunblind
Insulation
sides and
thedaken
roofsvan de
Isolatie vanofdethe
zijkanten
en de
of
the dormers
dakkapellen
Placement
or replacement
of
Plaatsen of vervangen
van beglazing
door gelaagde
glazing
by layered glazing
beglazing.
Placement
or replacement
of glazing
bygelaagd
layered
van beglazing
met
insulated
glazing,
A (U=+/-3.4)
isolerend glas,
typetype
A (U=+/-3,4)
van de
met
Placement
or replacement
of beglazing
the glazing
bydun
thin
double
glazing,
B (U=+/-1.9)
dubbel glas,
typetype
B (U=+/1,9)
Adding
safety
to originalaan
glass
Toevoegen
vanlayer
veiligheidslaag
oorspronkelijk
glas.
Sealing
thedeexterior
between
Opkittenat
aan
buitenzijde
tussenthe
deexterior
woodwork
and the carcass
en de ruwbouw.
Sealing
thedeinterior
between
thede
exterior
binnenzijde
tussen
Opkittenat
aan
woodwork
and the interior
finishing
en de binnenafwerking
Fig. 5a
Fig. 5b
D1.4.1
D1.4.2
D1.4.3
D1.4.4
Guillotineramen
- toevoegen
tegengewicht
Guillotine windows
- addingvan
counterweight
D3.1-5
Front doors--driepuntsluiting
three-point locks
Voordeuren
D3.1-6
Front doors--Tochtwering
Draught excluders
in the lower
Voordeuren
in de onderlijst
van het
strip of the door leaf
deurblad
Voordeuren
Front doors--Inbraakwerend
burglar-proofglas
glass
D3.1-8
D3.1-9
D4.1
D4.2.23
D4.2.24
Energy saving measures
for thevoor
rolling
shutters
Energiebesparende
maatregelen
de rolluiken.
D7.1.2
Aanpassingswerken
oorspronkelijke houten
Adaptation works onaan
thedeoriginal
wooden garage gates
garagepoorten.
Aanpassingswerken
oorspronkelijke
metalen
Adaptation works onaan
thedeoriginal
metal garage
gates (burglar-proof
glass) glas)
garagepoorten
(inbraakwerend
Portaal,
type 11 -- Adaptations
Wijzigingen en
werken
aan de
Portal, type
and
working
on the classed
existing toestand.
condition
geklasseerde
bestaande
Portal, type
and
working
Portaal,
Wijzigingen en
werken
aan de
on the classed
existing toestand.
condition
geklasseerde
bestaande
Portaal,
Wijzigingen en
werken
aan de
Portal, type
and
working
on the classed
existing toestand.
condition
geklasseerde
bestaande
Portaal,
type
- Wijzigingenand
en werken
aan de
ortal, type
44
- Adaptations
working
on the classed
existing toestand.
condition
geklasseerde
bestaande
Portaal,
Wijzigingen en
werken
aan de
Portal, type
and
working
on the classed
existing toestand.
condition
geklasseerde
bestaande
Non-original
parapets
and handrails
en handgrepen.
Niet
oorspronkelijke
borstweringen
D7.2.3
D8.1
D8.2
D8.3
D8.4
D8.5
E4.1.3
G1.11
G1.12
G1.21
G1.22
G1.31.1
G1.31.2
G2.10
G2.20
5.1 Performantie
Performancevan
of de
infrastructuur
infrastructureenand
equipment
uitrusting
2.6 Saneren
van vochtige
Decontamination
of
muren
en vloeren
damp walls
and floors
2.5 Isolatie
vanofde
Insulation
Roofs
voordeuren
the front doors
2.4 De
beglazing
Glazing
of thevan de
exterior woodwork
2.3 De daken
Roofs
2.2 Vloeren
boven niet
Floors above
verwarmde
non-heatedruimtes
2.1 De gevelmuren
Façade walls
1.5 Sanering
van vochtige
Decontamination
of
muren
en vloeren
damp walls
and floors
1.4 Zomerconfort
Summer comfort
1.3 Wegwerken
Eliminating van
cold
koudebruggen
bridges
Voordeuren
isolatie van
Front doors--Thermische
Thermal insulation
of deuren met
doors with
thin filling panels
dunne
vulpanelen
Front doors--luchtair and
proof profiles
Voordeuren
en sound
geluidsdichte
profielen
between
framesenand
wings
tussen
kozijnen
vleugels
Restitution
ofklapluiken
folding shutters
Restitutie
van
Restauratie
van rolluiken,
met betere aansluiting
Restoring rolling
shutters,
withde
better
connection of the parts
van
onderdelen.
Restitutie
van
Restitution
ofrolluiken
rolling shutters
D4.2.21
5.
5.
Other
Andere
Air-tightness of
opening
wingsvleugels –
Luchtdichtheid
van
opengaande
- restoration works
restauratiewerken
Air-tightness of
opening
wingsvleugels –
Luchtdichtheid
van
opengaande
- restitution works
restitutiewerken
Thermische
isolatie van
Thermal insulation
of exterior
woodwork –
- restoration works
restauratiewerken
Thermal insulation
of exterior
woodwork –
Thermische
isolatie van
- restitution works
restitutiewerken
D2.3.2-2
D3.1-7
1.2 Luchtdichtheid
Air-tightness ofvan
thede
exterior woodwork
Articles provided for in the technical specifications
T02)
Artikels voorzien in(book
de technische
voorschriften
(boek T02)
1.1 Compartimentering van
Compartmentalisation
de
ruimtes
of the
spaces
Huidige
behoeften
Current
needs
1. Hygrothermal measures
2. Energy savingdoor
by working
1. Hygrothermische
maatregelen
2. Energiebesparing
werken aan
forcomfort
comfortenand
health
onde
the
outer shell
voor
gezondheid
buitenschil
Thermische
isolatie van
houten dragende
vloeren
Thermal insulation
of wooden
load-bearing
floor above
accessible
spaces
boven
toegankelijke
ruimtes
Isolatie
vanof
dragende
vloerenfloors
uit beton
of holle or
Insulation
load-bearing
of concrete
hollow slabs
accessible
spaces
welfsels
bovenabove
toegankelijke
ruimtes
Thermische
isolatie van
dragende vloeren
boven
Thermal insulation
of load-bearing
floors
above
dry, inaccessible
spaces
droge
ontoegankelijke
ruimtes
Thermal insulation
of load-bearing
floors
above
Thermische
isolatie van
dragende vloeren
boven
humid, inaccessible
spaces
vochtige
ontoegankelijke
ruimtes
Verwijdering
van de bestaande
vloer voor de
Removal of existing
floor for treatment
of damp non-load-bearing
floors
behandeling
van vochtige niet-dragende
vloeren
Aanleg
van een
ondervloer
onder
Construction
ofdrainerende
draining blind
floor for
damp
non-load-bearing
floors
vochtige
niet-dragende
vloeren
Behandeling
tegen opstijgend
vocht
van muren
van
Treatment against
rising damp
in walls
of
spaces above
floors
ruimtes
boven self-supporting
zelfdragende vloeren
Behandeling
tegen
opstijgend
vocht
van
muren
van
Treatment against rising damp in walls of
spaces above
the ground
ruimtes
boven floors
vloerendirectly
op volleon
grond
Fig. 5a and 5b
Technical specifications extracted from The Le Logis and Floréal heritage management plan (© ARSIS).
43
ONLINE
Comfort & hygiene
Art.1.1. Compartmentalisation of the space
Art.1.2. Airtightness of the opening panes
Art.1.3. Airtightness of the connection
of the exterior joinery
Art.1.4. Removal of thermal bridges
Insulation of the shell
Art.2.1. Insulation of the façade
Art.2.2. Insulation of the floor
Art.2.3. Insulation of the roof
Art.2.4. Insulating glazing
Drawn up by
private limited
(House type LLw_D)
for the Brussels-Capital Region
Fig. 6
Various measures are presented on the plans for a specific type of house.
idea of the scale we can expect
regarding energy-efficiency and
costs. Additional audits will provide more information and provide
a clearer picture of the qualities of
the houses and the financial means
needed to realise the energy policy
of these social housing residences.
The return on investment time
(ROI) plays a crucial role in decisions, both short-term and medium-term. “Medium-term” means
a term which is reconcilable with
the 2040-2050 energy goals.
On the one hand, the estimated
costs of the works (as described
in detail in the management plan)
are taken into account when calculating the ROI. On the other
hand, the obtained energy saving
also plays a role in both the ROI
and the energy costs. The energy
saving is the difference between
the current consumption and the
estimated future consumption.
Over the years, it has become
ever clearer that energy use
models can divert greatly from
actual consumption. Old, non-insulated buildings appear to draw
their energy performance from
other, undocumented qualities.
They consume much less (up to
3 or 4 times less) than what can
be expected based on the calculations. In the past, this has also
been found to apply to the houses
of the Le Logis and Floréal garden cities. In the energy audit of
the two aforementioned houses,
it was therefore conservatively
assumed that the houses consume 2.5 times less than indicated
by the calculations5. This difference between actual and calculated consumption also leads to a
difference between the ROI based
on the actual consumption and
that based on the theoretical, calculated consumption.
With the goals for 2040-2050 in
mind, the following conclusion can
be made based on a preliminary
evaluation of the energy efficiency
of the measures provided in the
management plan:
• A 50% reduction in energy
consumption with a selection of
measures
a) with an ROI of less than 50 years,
calculated based on the actual,
measured consumption of the
houses;
b) with an ROI of less than 20
years, calculated based on the
theoretical, calculated consumption of the houses.
The measures considered feasible
are those with the shortest return
on investment time, namely:
1. insulating the roof and roof
windows;
2. making the shell airtight;
3. installing more efficient lighting;
4. installing more efficient heating;
The total costs for these measures
can be estimated at EUR 75 to
150/m² of heated floor space.
• A 75% reduction in energy
consumption is feasible by applying all of the measures provided
in the management plan.
The total costs for these measures
can be estimated at EUR 400 to
700/m² of heated floor space. This
includes the measures with a ROI
of 100 to 150 years, such as insulating the façades. This very long
ROI is, in combination with the
large impact on the heritage, the
reason why such works are subject
to a mandatory audit before the
Brussels-Capital Region can grant
subsidies for them.
For clarification and rectification
purposes, it must be noted that:
• these calculations are valid
assuming a steady energy price;
in the case of increasing prices,
the return on investment time
will decrease;
• these calculations do not take
future maintenance costs into
consideration, costs which are
certain to arise as the return
on investment times are quite
long. The maintenance costs will
increase the return on investment times.
CONCLUSION
The Heritage Management Plan
for the Le Logis and Floréal garden
cities became operational in 2014
in the legal framework for urban
development which recently came
into effect in the Brussels-Capital
Region. The instrument was realised over a period of 15 years and
in several phases and versions; the
energy section is fully integrated
in the most recent version. Thanks
to an in-depth study of the original
condition of the houses, the composition principles and the strengths
and weaknesses of the 1,060 residences, heritage-friendly measures
were provided to save energy and to
keep energy bills as low as possible for the residents. The position
taken here is to prioritise measures
which will result in a maximum
reduction to energy bills with a
minimum investment. Thanks to a
preliminary, calculated evaluation
(audit) the conclusion can be made
that it is possible to reduce the
energy bill of a residence by 50%
with affordable, energy-saving
and heritage-friendly measures
with am ROI of less than 20 or 50
years, depending on whether the
calculations are based on the calculated consumption or the actual
consumption.
This big difference shows, once
again, that:
• considerable, affordable energy
savings are possible and are also
feasible for large scale implementation;
• a deeper knowledge of the hygrothermal behaviour of historical
heritage is needed in order to
explain why current calculation
methods for energy consumption deviate considerably from
reality, and to understand that
standard solutions for energy
saving applied to newbuilds do
not deliver the expected results
or can even cause problems.
The complete Le Logis and Floréal
management plan can be found on
the website of the Direction des
Monuments et des Sites:
http://bit.ly/1iMnupW
NOTE
1. In 2007, two houses from Floréal were
added to the listing when it became
apparent that they too were built before
1940.
2. Houses were sold to private owners
from the outset.
3. For a possible energy upgrade of all the
Le Logis and Floréal houses.
4. The audit takes into account the specific
qualities of each house in its current
condition in relation to renovations,
energy measures, technical
installations, etc.
5. The actual consumption figures for the
two houses were incomplete, but based
on the figures available it is safe to
assume that they consumed more than
2.5 times less energy than calculated.
45
ONLINE
Les maisons classées des
cités-jardins Le Logis et Floréal :
adaptations aux besoins actuels
en énergie et en confort
Les cités-jardins Le Logis et
Floréal forment un ensemble
cohérent de rues, de places,
de chemins et de bâtiments.
L’équilibre général s’appuie
sur le leitmotiv «l’unité dans
la diversité, la diversité dans
l’unité», qui préside par ailleurs
à toute composition. Mais les
besoins et les attentes changent;
la performance énergétique et
le confort n’y échappent pas.
Au stade actuel, le plan de
gestion – adopté après quinze
ans d’évolution et premier de
ce type en Région bruxelloise –
concerne seulement l’enveloppe
extérieure des maisons et vise
prioritairement le maintien de la
cohérence de l’ensemble, tout en
permettant une réduction effective
des besoins en énergie. Il permet
de faire évoluer la situation
d’origine, de différentes manières,
en fonction de la performance
recherchée et de manière
compatible avec d’autres mesures.
Les solutions doivent également
rester équilibrées tant sur le
plan technique que financier. Le
plan de gestion s’est notamment
attaché à cela en opérant une
distinction entre les mesures de
confort, pour l’augmenter tout en
diminuant la demande en énergie,
et d’isolation. En effet, beaucoup
d’interventions liées au confort et
au climat intérieur des bâtiments
visent à réparer des dégradations
constructives. Dans ce cas, les
qualités patrimoniales du bâti
sont peu, voire pas, concernées.
En revanche, les mesures
d’isolation, qui doivent freiner la
conduction de l’énergie à travers
l’enveloppe extérieure, sont plus
intrusives et ont un impact sur la
valeur patrimoniale du bâtiment.
Ces mesures doivent donc être
subordonnées à des critères
d’efficacité, à évaluer précisément.
De beschermde huizen van de
tuinwijk Le Logis en Floréal.
Aanpassingen aan de huidige
energie- en comfortbehoeften
De tuinwijken Le Logis en
Floréal (1922-1940) vormen
een samenhangend geheel
van straten, pleinen, paden en
constructies. De evenwichtige
samenhang volgt het leidmotief
‘eenheid in verscheidenheid,
verscheidenheid in eenheid’,
in wezen de eigenschap van
elke geslaagde compositie.
De noden en verwachtingen
veranderen; en dat geldt ook
voor energieprestatie en comfort.
Het goedgekeurde beheersplan
viseert voorlopig slechts de
buitenschil van de huizen en
enkele ondergeschikte elementen
in de omgevingsaanleg. Het plan is
tot stand gekomen na een evolutie
van bijna 15 jaar en beoogt in
de eerste plaats het behoud van
de samenhang; het laat tegelijk
ruimte voor een toepasbare
en effectieve vermindering
van de energiebehoefte. De
oorspronkelijke toestand mag op
verschillende manieren worden
aangepast, in functie van de
beoogde performantie en van
de compatibiliteit met andere
maatregelen. De oplossingen
moeten technisch en financieel
evenwichtig zijn. Er wordt een
onderscheid gemaakt tussen
comfortgerichte en isolatiegerichte
maatregelen. De comfortgerichte
maatregelen beogen tegelijk het
verlagen van de energievraag en
het verhogen van het comfort. De
meeste van deze maatregelen
staan in verband met de sanering
van scheefgegroeide bouwfysische
omstandigheden, en nopen tot
weinig of geen veranderingen aan
het erfgoed. Deze maatregelen
verminderen de energievraag
in het binnenklimaat. De
isolatiegerichte maatregelen
beogen het verminderen van
energiegeleiding door de
buitenschil. Deze maatregelen zijn
meer ingrijpend ten aanzien van de
oorspronkelijke erfgoedtoestand
en zijn dan ook aan criteria van
efficiëntie gebonden.
47
ONLINE
FINANCIAL IMPACT OF ENERGY EFFICIENCY
MEASURES IN LE LOGIS AND FLORÉAL
JONATHAN FRONHOFFS
BUREAU CENERGIE CVBA
TWO HOUSES IN THE GARDEN CITY LE LOGIS AND FLORÉAL WERE EXAMINED.
THE GATHERED DATA WERE EXTRAPOLATED AND A MODEL CREATED WHICH
CAN BE APPLIED TO OTHER BUILDINGS IN THE GARDEN CITY. A HIERARCHY OF
INTERVENTIONS WAS DRAWN UP IN RELATION TO THEIR IMPACT ON ENERGY
CONSUMPTION AND RETURN ON INVESTMENT TIME.
In the course of this study two
buildings were audited: a threefaçade building on Kruisbooglaan
and a two-façade building on
Ibissenstraat. They were examined in order to extrapolate
energy saving measures for the
entire garden city at a later time.
The measures of course fit into
the management plan; a link is
made between the audit and the
management plan. For example,
the course of the ventilation tube
is clearly marked, through the
roof or through the side façades,
in particular colours.
Firstly, all losses through the building shell and the characteristics
of each building were analysed
(fig. 1 and 2).
The roof of the Ibissenstraat building was not insulated and 75% of
the energy loss was found to take
place through the roof. The opposite is true for the Kruisbooglaan:
the roof was insulated and we
ascertained that a large portion of
the losses occurred through the
façades. This is a three-façade
building so it is logical that a higher
Fig. 1
Ibissenstraat 5 in WatermaalBosvoorde
(A. de Ville de Goyet, 2015 © GOB).
Fig. 2
Kruisbooglaan 34 in WatermaalBosvoorde
(A. de Ville de Goyet, 2015 © GOB).
Ibissenstraat 5
Kruisbooglaan 34
Heated
190 m²
137 m²
Volume
338 m³
475 m³
approx. 1930
approx. 1930
/
/
Built
Most recent major renovation
Fig. 3
Buildings studied (© Cenergie).
48 | Financial impact of energy efficiency measures in Le Logis and Floréal
Sloped roof 57%
Floorboard 5%
Sloped roof 13%
Floorboard 3%
Façades 14%
Cellar steps 1%
Façades 40%
Cellar steps 1%
Cellar walls 2%
Wood 100SV 11%
Cellar walls 1%
Wood 100SV 19%
Front façade dormer 1%
Back door 6%
Front façade dormer 1%
Back door 1%
Board above attic 1%
Cellar door 1%
Board above attic 10%
Cellar door 1%
Fig. 4
Ibissenstraat 5: division of losses through transmission
per type of wall (© Cenergie).
proportion of losses occur through
the façades (fig. 3, 4 and 5).
Before measures are taken, the
building’s current energy use is
always examined first. This is true
of all cases, whether the building in question is listed or not.
Based on the invoices examined,
there was a factor of 3.4 to 3.8
between the actual value and normal consumption figures for this
type of building. A large discrepancy was thus immediately evident. A large difference between
theoretical and actual levels, for
example with a factor of 3.5 to 4
above, means that the theoretical
values are not actually realistic.
For this reason we delved into the
literature in order to find a more
realistic figure and ended up with
a factor of approximately 2.5 with
regard to the actual consumption
measured in these two houses.
The consumption based on the
gas invoice was low, though electric heating may be used by the
residents for additional heating,
which cannot be measured. This is
probably the reason for the large
difference (fig. 6).
Fig. 5
Kruisbooglaan 34: division of losses through transmission
per type of wall (© Cenergie).
Ibissenstraat 5
Kruisbooglaan 34
Consumption from
additional devices
Losses from
the residential hot
water systems
Losses from the
heating systems
Net energy needed for
residential hot water
Supply through
sunlight/internal
supply
Loss due
to ventilation
Loss due to
air leaks
Loss due to
transmission
Fig. 6
Final energy consumption of the two houses (© Cenergie).
49
ONLINE
If the global consumption - i.e.
including heating - between the
two houses is compared, we can
conclude that the Ibissenstraat
house had a greater loss through
the façades and the Kruisbooglaan
through the roof. These differences
are compensated for because one
home contained an old atmospheric boiler and the other a more
recent boiler. This more or less
creates a balance, which can be
seen in the difference between
the blue zone on the Ibissenstraat
house and the orange zone on the
Kruisbooglaan.
Research was carried out to determine all of the possible energy
saving measures which could be
applied to the building. The following is a complete list detailing the situation before and after
improvement works. When energy
saving measures are applied, one
measure will have an effect on the
following measure with regard to
the return on investment time and
savings. For example, by insulating
the façade first and then replacing
the boiler, the boiler will consume
less due to the façade insulation
and thus the boiler’s return on
investment time will improve.
Below are detailed the results if
the complete package of measures
is applied. Tables 1 and 2 show the
situation before and after applying
the measures. We can see that the
situation in both homes is more or
less the same. There are of course
a variety of priorities which could
be chosen to assess the efficacy
of various measures taken;. in
our case the return on investment
time has been used as the primary
assessment measure.
Area to be
improved
Performance
before
improvements
[W/m².K]
Improvement
Performance
after
improvements
[W/m².K]
Sloped roof
5.00
Interior insulation
0.33
Façades
1.60
Exterior insulation
0.58
Dormer front
5.62
Exterior insulation
0.31
Board above
cellar
1.36
Insulation under
0.54
Wooden window,
single glazing
5.24
Version A:
replaced with
laminated glass
(Ug=3.4 W/m².K) /
panel
3.16
Version B:
replaced with
double glazing
(Ug=1.9 W/m².K) /
panel
1.99
Version A:
replaced with
laminated glass
(Ug=3.4 W/m².K) /
panel
2.81
Version B:
replaced with
double glazing
(Ug=1.9 W/m².K) /
panel
2.05
Version A:
replaced with
laminated glass
(Ug=3.4 W/m².K) /
panel
2.77
Version B:
replaced with
double glazing
(Ug=1.9 W/m².K) /
panel
2.06
Bad
v50 = 12m³/h.m²
Improve
airtightness
Good5
v50 = 3m³/h.m²
Heating
Efficiency:
80%
No improvement
realised
Efficiency:
80%
Lighting
Several
incandescent
light bulbs
Replace incandescent
light bulbs with LEDs
Only low-energy
light bulbs
Ventilation
No ventilation
system
Natural air supply and
extraction via the wet
areas
+/- System C
Back door
4.80
Front door
Airtightness
4.46
Table 1
Measures Ibissenstraat 5 (© Cenergie).
Area to be
improved
Performance
before
improvements
[W/m².K]
Improvement
Performance
after
improvements
[W/m².K]
Sloped roof
1.03
Interior insulation
0.33
Façades
1.60
Exterior insulation
0.58
Dormer front
2.45
Exterior insulation
0.78
Board above
cellar
1.97
Insulation under
0.40
Wood, single
glazing
5.24
Version A:
replaced with
laminated glass
(Ug=3.4 W/m².K) /
panel
3.16
Version B:
replaced with
double glazing
(Ug=1.9 W/m².K) /
panel
1.99
Version A:
replaced with
laminated glass
(Ug=3.4 W/m².K) /
panel
2.81
Version B:
replaced with
double glazing
(Ug=1.9 W/m².K) /
panel
2.38
Back door
4.23
Veranda roof
2.26
Heated roof system
0.58
Attic roof
1.92
Insulation of the
wooden floor in the
attic
0.81
Veranda façades
2.84
Exterior insulation
0.70
Bad
v50 = 12m³/h.m²
Improve
airtightness
Good5
v50 = 3m³/h.m²
Heating
Efficiency:
65.40%
No improvement
realised
Efficiency:
83.02%
Lighting
Several
incandescent
light bulbs
Replace incandescent
light bulbs with LEDs
Only low-energy
light bulbs
Ventilation
No ventilation
system
Natural air supply and
extraction via the wet
areas
+/- System C
Airtightness
Table 2
Measures Kruisbooglaan 34 (© Cenergie).
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Significantly, interventions in an
old building can be more expensive than in a “regular” building.
For example: in one of the two
homes the façade insulation costs
between EUR 400-500 /m2, while in
a classic building the cost ranges
from about EUR 100-150.
Different improvement priorities
were applied for each building as well
as for each scenario: scenario 1 was
the purely theoretical value; scenario
2 was the revised theoretical value,
which is closer to the actual value for
energy consumption.
The heating in the Ibissenstraat
home was the last priority because
it had a good boiler but the roof was
not insulated. The priorities were
thus firstly insulating the roof,
then the building shell and, somewhere in the middle, the windows.
The return on investment times in
scenario 1 is three years for the
roof and 90 years for the façades.
But scenario 2 gives 300 years for
the façades’ return on investment
time; for this reason this measure
was not applied.
Conversely, in the Kruisbooglaan
home heating was the priority – the
house had an old boiler situated
outside the protected volume in
the cellar. Replacing this was prioritised. A similar list then follows,
with the façades again at the very
end. Scenario 1 gives us 60 years
if we take the longest return on
investment time; that becomes 166
years when a more realistic existing energy consumption is applied.
Final energy use - Ibissenstraat 5
Before improvement
After improvement
Energy use for lighting
Additional energy consumption
Loss through SWW system
Loss through heating system
Net energy required for SWW
Net energy required for heating
Fig. 7
Savings Ibissenstraat 5. Primary energy consumption (© Cenergie).
Final energy use - Kruisbooglaan 34
Before improvement
After improvement
Energy use for lighting
Additional energy consumption
Loss through SWW system
Loss through heating system
Net energy required for SWW
Net energy required for heating
Fig. 8
Savings Kruisbooglaan 34. Primary energy consumption (© Cenergie).
The full audit is available on
the website of the Direction des
Monuments et des Sites:
http://bit.ly/1GPWL0X
IBISSENSTRAAT 5:
RETURN ON INVESTMENT TIME - SCENARIO I
IBISSENSTRAAT 5:
TERUGVERDIENTIJD - SCENARIO II
Priority in relation to the return on
investment time Improvements
Priority
Sloped roof
ROI (years)
1
Sloped roof
3
2
Front façade
dormer
3
4
5
Priority
Sloped roof
ROI (years)
1
Heating
5
3
2
6
Airtightness
13
3
Board above
cellar
Front façade
dormer
Board above
cellar
Wood, single
glazing
15
4
Airtightness
7
Version A: 38
Version B: 42
5
Attic roofing
8
6
6
Sloped roof
18
6
Back door
Version A: 39
Version B: 45
7
Veranda façades
20
7
Front door
Version A: 46
Version B: 51
8
8
Façades
91
Wood, single
glazing
Version A: 36
Version B: 39
9
Back door
9
Heating
0
Version A: 39
Version B: 48
10
Façades
60
KRUISBOOGLAAN 34:
RETURN ON INVESTMENT TIME - SCENARIO I
KRUISBOOGLAAN 34:
RETURN ON INVESTMENT TIME - SCENARIO II
Priority
Sloped roof
ROI (years)
1
Heating
5
2
Board above
cellar
3
Priority
Sloped roof
ROI (years)
1
Lighting
6
6
2
Heating
13
Front façade
dormer
6
3
Front façade
dormer
17
4
Airtightness
7
4
Board above
cellar
18
5
Attic roofing
8
5
Airtightness
20
6
Sloped roof
18
6
Attic roofing
21
7
Veranda façades
20
8
Wood 100SV
Version A: 36
Version B: 39
7
Veranda roofing
28
8
Sloped roof
50
9
Back door
Version A: 39
Version B: 48
9
Veranda façades
56
10
Façades
60
10
Wood 100SV
Version A: 100
Version B: 106
11
Back door
Version A: 108
Version B: 133
12
Façades
166
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Impact financier des mesures
d’économie d’énergie dans
Le Logis-Floréal
Financiële impact van
energiebesparende maatregelen
in Le Logis-Floréal
Afin d’élaborer des mesures
prioritaires, deux audits
énergétiques détaillés
ont été réalisés. Les deux
immeubles ont tout d’abord
été analysés sous l’angle de
leurs installations (le chauffage,
la ventilation, l’éclairage…)
et de leurs consommations
d’énergie. L’analyse de ces
dernières a montré qu’elles
étaient particulièrement basses
par rapport aux valeurs de
consommation théoriques.
Ces données de consommation
réelles ont donc été extrapolées
et modélisées pour pouvoir
travailler sur d’autres bâtiments
du Logis-Floréal. Les mesures
d’intervention établies sur la base
de l’audit de ces deux immeubles
ont été classées selon quatre
niveaux de priorité en fonction
de l’impact sur la consommation
d’énergie et du délai de retour sur
investissement. Elles ont ensuite
été confrontées au plan de gestion
patrimonial du Logis-Floréal,
pour y être intégrées.
Om prioritaire maatregelen uit te
werken, werden twee gedetailleerde
energie-audits uitgevoerd. Eerst
werden de twee gebouwen
geanalyseerd op het vlak van hun
installaties (verwarming, ventilatie,
verlichting...) en energieverbruik. Uit
de analyse van de energieverbruiken
bleek dat er bijzonder lage
verbruiken geregistreerd waren
ten opzichte van de theoretische
verbruikswaarden. Deze werkelijke
verbruiksgegevens werden
vervolgens geëxtrapoleerd en
gemodelleerd om bruikbaar te zijn
voor andere gebouwen van LogisFloréal. De interventiemaatregelen
die op basis van de audit van
deze twee gebouwen werden
uitgewerkt,werden volgens 4
prioriteitsniveaus gerangschikt
naargelang hun impact op
het energieverbruik en de
terugverdientijd. Daarna werden
ze getoetst aan en verwerkt in het
beheersplan van Logis-Floréal.
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ANALYSIS OF UNCERTAINTIES IN DYNAMIC
THERMAL SIMULATIONS FOR OLD HOUSING:
A CASE STUDY OF ONE APPARTMENT AND ONE
HOUSE IN THE PARIS REGION
JULIEN BORDERON
CENTER FOR EXPERTISE AND ENGINEERING ON RISKS, URBAN AND COUNTRY PLANNING, ENVIRONMENT
AND MOBILITY (CEREMA) - REGIONAL LABORATORY OF STRASBOURG (FRANCE)
THE EXISTING TOOLS FOR EVALUATING BUILDINGS AND THE UNCERTAINTIES
ASSOCIATED WITH THE INPUTS FOR DYNAMIC THERMAL SIMULATIONS ARE
PRESENTED, ALONG WITH A WAY OF EXAMINING THE LIMITATIONS OF MODELS
WHEN APPLIED TO EXISTING BUILDINGS.
This presentation centres on the
method that we have applied to a
certain number of buildings and
that we continue to use. In fact, our
approach has been deemed sufficiently beneficial by the French
Ministry of Ecology, Sustainable
Development and Energy that we
have been asked to go even further. I will illustrate my talk with
studies carried out on an apartment located in a building in the
16th arrondissement of Paris and a
house in the inner suburbs of Paris
(figs. 1 and 2).
THERMAL SIMULATION
APPLIED TO OLD BUILDINGS
Dynamic thermal simulation is one
of the common auditing tools for
buildings and therefore also for old
housing. In fact, to perform a general audit, a number of aspects are
worked on: the health of the building; its functional state; its suita-
bility for purpose; the comfort of
occupants; its strengths and weaknesses; its heritage status and elements that need to be preserved
are evaluated. The energy status
of the building is also addressed
through consumption, thermal
efficiency, performance of systems and management and use. It
is then possible to use simulation
tools, if there is sufficient concern, to compare or test different
packages of solutions. An attempt
is made, via this energy audit, to
determine typical consumption
and how it is broken down by type of
use in order to obtain itemised distribution graphs of heat loss. The
ultimate objective is to establish
priorities. This also enables the
building’s behaviour when used in
another way and/or independently
from the occupant’s habits to be
simulated. To explain this further:
the energy bills of a person heating
an apartment to 26°C are higher
than those of a person heating
56 | Analysis of uncertainties in dynamic thermal simulations for old housing
the same place to 20°C. Thermal
simulation of a building allows the
consumption specific to an apartment in a classic usage scenario to
be determined. In France, we refer
to the conventional usage scenarios of the thermal regulations. A
reference condition can therefore
be obtained prior to works being
carried out and used to model
different simulations of packages
of work. In order for our simulations to be reliable and be able
to forecast the investment payback period, precise and realistic
data are required. If our target is,
for example, 80 kWh/m²/year
and our initial situation indicates
200 kWh/m²/year, even though
in reality our building is at 150,
the general saving produced by
the works will be a lot less than
expected. It will therefore be
harder to pay off the investment
and could even result in a situation whereby it is not economically
viable. Simulation also facilitates
Fig. 1
Two-family house in Noisiel (France). Early 20th century.
The street-side façade is west facing (© Cerema).
an understanding of the building’s
behaviour in a summer comfort
configuration, especially in a scenario of global warming and more
frequent summer heat waves.
In order to use this thermal simulation tool for old or existing buildings, it is necessary to know what
input data are available. Are they
sufficiently reliable? Are significant errors produced when using
the default values?
The first stage in the technique
involved collecting information
on the two dwellings presented
below. Certain information is
obtained more easily than others.
We realise that in the current case,
where the modellers are neither a
specialised consultancy firm nor
an architectural firm specializing in the area, accessing data
soon becomes complicated. Our
work involved preparing models
with the necessary input data and
Fig. 2
Parisian apartment.
Late 19th/early 20th century (© Cerema).
Sources of uncertainty design assumptions
U values opaque walls
U values glass walls
Solar factors glass wall
Nearby masks
Distant masks
Linear thermal bridges (psi value)
B values, wall in contact with unheated space
Mechanical ventilation flow rate bathroom/kitchen
Natural ventilation flow rate by opening windows
Opening window scenario
Closing sunscreens scenario
Presence in apartment scenario
Solar processor for radiators on vertical surfaces
Internal contribution from electricity
Internal contribution from cooking
Internal contribution from domestic hot water
Average set-point temperature of temperatures measured
in the house
Inertia class
Building orientation
From
measurement or
expert appraisal
E
E
E
M
M
E
E
E, CF
CF
E, M
E, M
E, M
M, calculation
M, calculation
E
M, E
Typical
uncertainty
15
%
10
%
20
%
5
%
30
%
30-50
%
15
%
100
%
100
%
100
%
Extreme: all open all closed
30
%
see report
%
10
%
50
%
50
%
M, calculation
0,7 k
E, CF
M, E
1 class
0%, verif.
%
E, M
M
E, M
calculation
20/50
5
7
5
%
%
%
M
M,E
7
20
%
%
Sources of uncertainty measurement assumptions
Breakdown of energy domestic hot water/cooking/heating
Accuracy of energy sensors
Accuracy of temperature measurement
Boiler output
Accuracy of weather data
Accuracy of I4 air tightness measurement
Distribution of electricity consumption over the year
KEY
Transmission via the walls
Solar contribution
Internal contributions
Renewal of air
Other
Fig. 3
Typical input uncertainties (source: Cerema).
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estimating the associated uncertainties, whether these are due
to the reliability of the information collected or the confidence
interval of the typical values
used. A certain number of simulations of local and global sensitivity analyses were then carried out to assess the impact of
these uncertainties on the result
in terms of the energy audit. We
used a research version of a software tool similar to that used by
the French thermal regulation on
existing buildings. That is to say,
we were not bound by the calculation conventions imposed by the
reference scenarios. We used a
weather file measured locally on
an hourly basis¹, presence scenarios, internal contributions on
an hourly basis and ventilation
by opening windows on an hourly
basis (with a fixed flow rate) to
establish a working hypothesis.
Air permeability was in this case
measured using a blower door.
Around thirty inputs are listed (fig. 3).
We have detailed knowledge of
some of these inputs, and less
about others. For example, it is
estimated that there is a margin of
error of only 10% for the U values
of glass walls. However, we had
difficulty in estimating the distant
masks, i.e. shade on the building. Internal contributions are
also not very well known (evaluated at around 50%), because use
of household appliances varies.
There are therefore uncertainties
around this input data, the propagation of which are assessed until
output.
CASE STUDY 1:
THE WORKER’S HOUSE
IN NOISIEL
This is a traditional, brick,
two-family, worker’s house in the
Paris suburbs (fig. 1). It is a typical
building of this geographical sector. The building is symmetrical,
has two storeys and an occupied
attic space. The bricks, arranged
in two thicknesses, are externally
rendered. There is also an interior
plaster render. Certain windows
were replaced by double-glazing
around 1985-1990. Other windows
are single-glazed. Natural ventilation is used with the exception
of mechanical ventilation that was
recently added in a laundry. It is
a building in the somewhat heavy
thermal inertia class, with significant slabs particularly the one over
the brick cellar with jack arches
and double brick walls. The house
is occupied by a total of three
adults who all work.
My department monitored annual
consumption with electronic meters
so as to compare readings and
calculations. All the data are summarised in a graph (fig. 4). Total
consumption for this house of 106 m²
amounts to 241 kWh/m²/year, which
is around the French average. Gas is
responsible for 194 kWh/m²/year,
mainly for heating (domestic hot
water is also provided by the boiler).
I will comment on this item in particular.
The first step involved propagating
the basic uncertainties. To do this,
we took the uncertainty about each
item of input data, separately from
the others: 29 of them are fixed
and one moves. We then examined the impact on the results by
setting that item at both maximum
and minimum limits. The results
of this exercise are illustrated in
the graph of propagation of basic
uncertainties (fig. 5).
Let’s take a look at some of the
results. If we take the U values
of opaque walls (i.e. the brick
walls and the roof) we see that
by increasing the values deter-
mined after our on-site visit by
15%, the heating requirements of
this house increase by 14%. We
are therefore almost at 1 to 1. The
inverse is also true: if the values
are reduced by 15%, the heating
requirements are reduced by just
under 14%. Temperature is also an
important variable, therefore air
temperatures in the house were
measured. An average was then
calculated for the house based on
these measurements in the rooms.
A variation of 0.7°C of the set-point
temperatures in the modelling,
corresponding to the upper range
of uncertainty regarding the actual
interior temperatures measured,
implies a 10% shortfall in heating requirement. Site measuring is also important and is often
under-estimated. In effect, if we
are 7% out in the estimate of heat
loss surfaces, a shortfall of 7, 8
or 9% in heating requirements in
a winter scenario is easily possible (the study was not concerned
with what happens in summer).
However, it is known that the
margin of error with laser measurements is 3% to 4% and not all
auditors carry out site measuring;
some instead work using the construction plans. Input inaccuracies
in our simulation model therefore
have an immediate impact on the
results and it is important to be
aware of them in order to focus
on input data with a significant
impact.
The second step involved a global
analysis of all of the propagated
uncertainties using a statistical
method, namely the Monte-Carlo
method. 1,000 simulations with
drawings from all of the input data
were run. The resulting curves (fig. 6)
represent the 95% confidence
interval of the heating energy consumption of the house. The initial
finding was that the curves do not
perfectly overlap. This is due to the
Day of the year
Gas cooker
Domestic hot water
Heating
Lighting
Electricity other than lighting
Fig. 4
Annual monitoring of consumption of the house in Noisiel (source Cerema).
(Input difference A, Input difference B)
difference between the measurement and the calculation, which
means that my simulation is not
necessarily close to the reality.
There are multiple explanations
for this: certain physical phenomena are not modelled by the calculation engine, such as hygroscopic
inertia, for example. Our behaviour
scenarios are less complex than
actual family life. Nevertheless,
we find that the dotted curves on
either side of the bold curves form
a significant range that represents
the uncertainties about the model’s
input data. This illustrates well the
importance of paying attention to
these uncertainties when running
simulations. In fact, it is necessary
to be aware of the differences and
the range of responses that can be
obtained.
kWh/day
Solar factor opaque wall (+50%, -50%)
Linear length (+15%, -15%)
A Opaque walls + bay windows (+5%, -5%)
A Opaque wall only (+7%, -7%)
A bay windows (+5%, -5%)
Accuracy weather data air temp. (-2K, +2K)
Accuracy weather data wind speed (+10%, -10%)
Accuracy weather data exterior temp. (-0.5K, +0.5K)
Accuracy weather data solar radiation (-5%, +5%)
Accuracy measurement of I4 air permeability (+7%, -7%)
Building orientation (-, -)
Inertia class (-1 class, +1 class)
Average temperature measured in the house (+0.7K, -0.7K)
Internal contribution from domestic hot water (-50%, +50%)
Internal contribution from cooking (-50%, +50%)
Internal contributions from electricity (-10%, +10%)
Contributions due to occupation in the house (-30%, +30%)
Closing sunscreens scenario (all open, all closed)
Opening windows scenario (x2, =0)
Natural ventilation air flow by opening window (x2, /2)
Mechanical ventilation air flow bathroom/kitchen (x2, =0)
b values, walls in contact with unheated space (+15%, -15%)
Linear thermal bridges (psi value) (+50%, -50%)
Distant masks (+30%, -30%)
Nearby masks (+5%, -)
Solar factors glass walls (-20%, +20%)
U values glass walls (+10%, -10%)
U values opaque walls (+15%, -15%)
Relative differences B
Relative differences A
Fig. 5
House in Noisiel. Step 2, static. Propagation of basic uncertainties
(source: Cerema).
Fig. 6
House in Noisiel. Step 3, week by
week. Annual curves on the confidence
interval in kWh/week/m². The
measurement, in blue, also includes
an uncertainty, as our sensors are
not 100% reliable. Furthermore, the
breakdown between hot water and
heating is not clear (source: Cerema).
Pivotal calculation
Pivotal measurement
-2K measurement
-2K calculation
+2K measurement
+2K calculation
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We’ll now focus on one particular
week in winter to take a detailed
look at what is happening (fig. 7).
The temperature of the house is
stable, with a low inertia effect.
The external temperature is cool
and variable. We can see that the
curve corresponding to the measurement displays more significant
variations than the simulation
curve, even though the set-point
temperatures of the simulation are
those that were measured (fig. 8).
From a consumption point of view,
this means that the boiler, in reality, is continually stopping and
starting, a phenomenon that is
not taken into account by the simulation. This typically illustrates
a difference arising from the way
in which the calculation engine
takes the reality into account. In
practical terms, the calculation
somewhat smooths out the heating system even though, in reality,
an old boiler operates a lot less
smoothly. Inversely, when the
heating flow is imposed on the
model and changes in temperature are observed, we notice that
changes are much more marked
in the calculation. In this case, the
inertia of the heating system is not
taken into account in the calculation, which constitutes yet another
bias of my mathematical tool. This
phenomenon is not very significant over an average. However, it
becomes very significant when we
look at exactly what happens on
an hourly basis.
CASE STUDY 2:
THE PARISIAN APARTMENT
The apartment dates from the late
19th/early 20th century (fig. 2). With
a surface area of 108 m², comprising three bedrooms, it is located
on the 5th floor of a handsome
apartment building. The façades
are made from hard limestone
Temperatures over 3 weeks on either side of the period studied
Interior temperature
External temperature
Fig. 7
Dynamic analysis over one week (source: Cerema).
Measurements
Temp. calculation imposed
Fig. 8
Changes in heating output measured and calculated.
The interior temperature is imposed (source: Cerema).
(called Paris stone) with beautiful dressed stone on the external
street-facing side and plaster render on the interior walls. Thinner,
less elaborate breezeblocks covered in render are found in the
courtyard-facing side. Paris stone,
which is very hard, offers very
poor thermal conductivity for a
limestone. All of the windows are
single-glazed and original. They
are thermally inefficient. A family
of two adults and two teenagers
occupies the apartment. All family
members are occupied during the
day. There is no mechanical ventilation apart from a basic extractor
in the bathroom, added retrospectively. The family opens the windows every day.
The same method as previously
was applied. This gives a graph
of annual consumption (fig. 9).
Energy consumption is a bit
lower than the house in Noisiel:
165 kWh/m²/year, the correct figure for a building with single glazing. The extreme contiguity plays
a positive role here. The occupants, who are quite well off, have
no hesitation in turning on the
heating; we are not dealing with
a scenario of energy insecurity
here that would require the setpoint temperatures to be lowered.
On the contrary, the apartment
is comfortable but, nevertheless,
does not consume a particularly high amount of energy. This
example illustrates how certain
The propagation of basic uncertainties is relatively similar to
those from the first case study.
Nevertheless, it should be noted
that in this case there are a greater
number of glass walls, meaning
that there is greater uncertainty in
relation to this item. The opaque
walls also play an important role
here (though less than in the previous example) with a 15% input difference implying a 10% output difference for the heating. One reason
for this could be the solar factor of
the opaque walls, which we do not
completely understand. This can
produce a difference of up to 1.5%
in consumption. All of these small
errors, when put together, ultimately produce significant output
errors. The annual curves representing the overall uncertainties
again evidence in the same difficulties outlined above in relation
to matching the calculations with
the measurements in the field. For
this building, the bias arises from
our lack of information about the
adjoining apartments, which is
limited to temperature measurements.
I would like to mention an interesting bias relating to the calculation engine. The apartment is
southeast facing. The first version
of the calculation engine that we
used took the general orientation into account as either due
north, due south, due east or due
west. However, by using a second,
improved version of the calculation engine which enabled the
exact orientation to be taken into
account, divergences emerged in
the results. When it was due south,
consumption fell by 8%; when
due east, it increased by 5%. This
showed once again the importance
kWh/day
old buildings can consume less
energy than buildings from the
1960s or 1970s.
Day of the year
Gas cooker
Domestic hot water
Heating
Lighting
Electricity other than lighting
Fig. 9
Annual monitoring of apartment’s consumption (source: Cerema).
of inputting precise data in the calculation engine, including orientation.
CONCLUSION
In conclusion, for our two buildings,
the input parameters with the biggest impact on the results of these
dynamic simulations were the U
value of opaque walls, the average temperature measured in the
apartment (a deviation of less than
one degree from the set-point temperature has a significant impact
on consumption) and site measuring. This fact is often forgotten,
especially with these buildings.
However, not having the architect’s
blueprints, drawing them up in situ,
or making estimates based on inaccurate documents can have major
effects on the calculations. Finally,
the closing of sunscreens scenario
also plays its role, in particular in
the extreme cases of where they
are closed during the day or not
used at all.
The annual heating projection
graphs (fig. 10 and 11) were produced
with very poor simulation data
because the extremes of the input
uncertainties had been used,
which, statistically, have a very
low chance of occurring. The blue
bell curves, which are the outputs obtained with the simulations, are very wide. This means
that the average measurement,
which according to my simulations
should be 125 kWh/m²/year for the
Parisian apartment with regards
to heating, may increase to a maximum of 175 kWh/m²/year and
decrease to a minimum of 75 kWh/
m²/year.
Once again, it is very difficult to
“tune” the measurement to the
calculation. Clearly, the data used
could be refined. However, we
deliberately put ourselves in a situation which consultancy firms frequently encounter, namely a lack
of time and difficulty in collecting
information. A consultancy firm
working on dynamic thermal simulations is not going to spend three
weeks collecting input data; there
will therefore be a lack of precision
in its results. We therefore worked
within this realistic constraint.
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This doesn’t mean that such tools
should not be used, simply that one
must keep in mind that there are
uncertainties and that those uncertainties propagate. These calculation engines are powerful tools
for comparing different solutions.
However, to achieve the most optimal results, it is necessary to work
with a range of values of a realistic span (and not a value of 2 kWh/
m²/year). After carrying out work,
the more in-depth knowledge of
the package of works applied may
enable future consumption to be
correctly simulated, but any saving
(which is the difference between
consumption before and after the
works) will always be inaccurate
for all the reasons stated above,
most notably that relating to the
initial condition of the building.
Parisian apartment.
House in Noisiel.
KEY
The measurement (with the uncertainties linked to the sensors and the
breakdown of consumption by item)
Model
Fig. 10 and 11
Probability curves of heating requirements in kWh/m²/year. If care isn’t taken, the
heating requirements can vary significantly with major uncertainties in relation to
the input data (source: Cerema).
NOTE
1. Field of variables calculated on
an hourly basis (depending on the
weather station and simulations).
Analyse des incertitudes sur
des simulations thermiques
dynamiques de logements
anciens : cas d’un immeuble
et d’une maison en région
parisienne
Les simulations thermiques
dynamiques (STD) de logements
sont de plus en plus répandues
dans le cadre de projet de
réhabilitation. Les difficultés
d’obtention de certaines données
d’entrées, la difficulté d’être précis
dans l’utilisation de scénarios
stochastiques, pour certains
paramètres liés à l’occupation ou
l’usage du bâtiment, mènent à de
larges incertitudes sur les entrées
des modèles de simulation.
Pour pointer le « coût » en précision
lié à toutes ces incertitudes, deux
cas de logements anciens ont été
étudiés : un appartement dans un
immeuble post-haussmannien et
une maison ouvrière du début du
XXe siècle. Pour ces logements, un
monitoring des consommations et
des ambiances est disponible dans
le cadre d’un projet de recherche
plus vaste. Des simulations avec un
outil de STD avec des propagations
d’incertitudes sont réalisées.
Les comparaisons mesures/calculs
avec des bandes d’incertitudes
permettent de montrer les
limites de l’outil par rapport à
la connaissance des entrées
des modèles. Les incertitudes
sur certaines entrées sont
particulièrement importantes sur
des bâtiments anciens.
Analyse van de onzekerheden
over de dynamische thermische
simulaties van oude woningen:
geval van een gebouw en een huis
in de Parijse regio
Er worden steeds meer
dynamische thermische
simulaties (DTS) van woningen
uitgevoerd in het kader van
herwaarderingsprojecten.
De moeilijkheid om bepaalde
inputgegevens te verkrijgen en om
nauwkeurig te zijn in het gebruik
van stochastische scenario’s
voor parameters gelinkt aan de
bezetting of het gebruik van het
gebouw leidt tot grote onzekerheid
over de inputgegevens van de
simulatiemodellen.
De impact van al deze variabele
gegevens wordt geïllustreerd aan
de hand van twee cases van oude
woningen: een appartement in
een gebouw in post-Haussmanstijl en een arbeiderswoning van
het begin van de 20ste eeuw.
Voor deze woningen werden het
verbruik en het effect van de
omgevingsfactoren gemonitord
in het kader van een ruimer
onderzoekproject. Er worden
simulaties met de DTS-tool
uitgevoerd waarin gekeken
wordt naar het effect van deze
variabele gegevens om aan
de hand van vergelijkingen
(metingen/berekeningen)
met onzekerheidsmarges de
beperkingen van deze tool aan
te tonen. In oude gebouwen
spelen deze variabelen in de
inputgegevens immers een
bijzonder belangrijke rol.
63
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RISK ANALYSIS FOR APPLYING INTERIOR
INSULATION IN HISTORICAL BUILDINGS:
A CASE STUDY OF THE FORMER VETERINARY
SCHOOL IN ANDERLECHT
ROALD HAYEN
ROYAL INSTITUTE FOR CULTURAL HERITAGE (KIK-IRPA).
THE RENOVATION OF HISTORIC BUILDINGS OFTEN REQUIRES THE OUTER SHELL TO
BE INSULATED. HOWEVER, SUCH TASKS ARE NOT ALWAYS COMPATIBLE WITH THE
HISTORICAL CHARACTERISTICS OF THE BUILDING. A STUDIES CARRIED OUT ON
INTERIOR INSULATION AT THE OLD VETERINARY SCHOOL HAVE BROUGHT THE RISKS
INHERENT TO SUCH WORKS TO LIGHT, AS WELL AS THEIR POTENTIAL IMPACT ON
THE PROTECTION OF THE BUILDING’S MONUMENTAL FAÇADES IN BRICK, EUVILLE
LIMESTONE AND BLUESTONE.
HISTORY OF THE VETERINARY
SCHOOL IN ANDERLECHT
In around 1761, the very first veterinary school was established in
Lyon by Claude Bourgelat, a veterinary surgeon who was searching for a remedy for the ruminant
infectious disease rinderpest,
which plagued France at the time
(Wikipedia, 2015). This initiative
was being repeated throughout the
whole of Europe by the late 18th
and early 19th century. Initially, the
first veterinary surgeons focused
primarily on (army) horses. A veterinary school was also established in the United Netherlands
in this period, in Utrecht (1821).
Several years later, when Belgium
seceded from the Netherlands, it
quickly became clear that the gap
which had been created had to be
filled. There was an acute need for
veterinary education, both to serve
the army and to improve the indigenous cattle and horse breeds.
Above all, the authorities’ costs
for the mandatory slaughter and
monetary compensation of sick
cattle were much too high and
they therefore wished to focus on
healing the animals instead. Two
private initiatives were started as
early as 1832: a limited education
in veterinary medicine in Liège by
Pierre-Antoine Pétry; and the École
d’Économie Rurale et Vétérinaire,
initiated by André-Joseph Brogniez
in Binche (Bogaerts, 2015). Shortly
after, Brogniez relocated his school
to an old riding school in the centre of Brussels, where the Museum
for Fine Arts is now located. In
May 1836, this Brussels school
was taken over by the authorities
and reformed into the École de
Médecine Vétérinaire et d’Agriculture de l’état. The original school
moved to the territory belonging
to Kuregem, near a rural area and
the slaughterhouse in Anderlecht
yet still not too far from Brussels.
Brussels’ urban development in
the first half of the 19th century
was indeed limited to the zone
within the second medieval city
wall. The current inner ringroad,
also known as the Small Ring,
follows the path of this wall.
Originally, the school was nestled along what is now the
Poincarélaan, on both sides of the
Lesser Senne river. Regular flooding of the Senne caused a great
64 | Risk analysis for applying interior insulation in historical buildings: a case study of the former veterinary school in Anderlecht
the entirety formed by these buildings and the park in which they are
located was listed as a protected
landscape. However, this protection did nothing to hinder the
decades-long neglect that was to
follow.
Fig. 1
View of the main administrative building, according to a postcard dating from the
early 20th century (verzameling Belfius Bank-Académie royale de Belgique©
ARB-GOB).
Fig. 2
View of the rear façade after more than 20 years of neglect (photo by author).
number of problems. After some
time, the school also stood in the
way of Brussels’ urban development, so at the end of the 19th century the decision was made to move
the school to the site which is now
the Veeartsenstraat. The current
building was realised, under architect Seroen’s supervision, in the
1903-1909 period and was officially
inaugurated on 14 August 1910 on
the occasion of the Brussels World
Expo (ARTER, 2012).
In 1969, the veterinary school
became part of the University of
Liège. Throughout the years, various parts of the school gradually
moved to the campus in Liège and
in 1991 the site was left completely
desolate. In 1999, Anderlecht
Municipality became the owner of
the administrative building on the
street side. In the meantime, on
22 February 1990, the façades and
roofing of the original buildings
were declared monuments and
The veterinary school forms an
extensive pavilion complex with
a total of 19 buildings in Flemish
neo-Renaissance style and large
green spaces in between. The veterinary school of Hanover was the
inspiration for architect Seroen
when designing the pavilion complex (ARTER, 2012). At the start of
this study, various pavilions had
already been restored. The study
was therefore limited to the former main administrative building,
located on the Veeartsenstraat
(fig. 1). The monumental front and
side façades are made predominantly of Euville limestone with
parts in bluestone. The south west
facing rear façade is for the most
part brick. The results of the more
than 20 years of deterioration are
clearly visible (fig. 2): the jointing
has all but disappeared in various
places; the limestone elements
often show considerable loss of
material and crack forming; and
biological corrosion runs rampant,
from lichens and moss to small
trees sprouting from brickwork at
the top of the façade.
PLANS FOR THE FUTURE
If a monument cannot be reinstated to its original function,
then an appropriate new use is
essential for sustainable conservation. It was decided to turn the
main building into a centre for
young businesses. The architectural project, which was entrusted
to ARTER (a different architect is
being used for the interior: HASA
Architecten bvba), is endeavouring
65
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to combine old and new: new floor
levels were added to increase the
amount of usable floorspace while
at the same time maintaining the
existing interior elements (oak
floors, marble mosaics, historical
carpentry, etc.) to the maximum
extent possible. This is all being
done with the intention of turning
the building into a low-energy office
building after its transformation.
According to a study of the energy
consumption carried out by the
design and construction consultancy bureau Daidalos Peutz, the
primary energy consumption was
initially (i.e. before works) estimated at 400 kW/m²a - which
delivers an E-level of 180 and a K
level of 110 for the building shell
(Daidalos, 2011). To calculate this
estimate, the existing building
shell as well as a new technical
installation for heating, cooling,
lighting and sanitary fittings were
taken into account. As the original installations are missing - and
most likely cannot be adequately
simulated in accordance with
existing calculation modules - this
estimate delivers a lower limit with
regard to the original consumption.
However, this result does reflect
the consumption to be expected if
no architectural adaptations were
made to the construction. Since
this energy consumption does not
meet the current energy standard
for new-built office buildings in
the Brussels metropolitan area, a
decrease in the energy consumption was desirable, although such
monuments are in principle not
subject to this regulation.
As heating was estimated to make
up approximately three-quarters
of the total energy consumption
in the building’s initial state, an
improvement to the insulation
value of the building shell would
immediately lead to a considerable
Buildings
Current
value
(W/m²K)
Solution A Solution B
(W/m²K)
(W/m²K)
Maximum
U value
(W/m²K)
Roof
3.8
0.26
0.26
0.30
Façade
1.0
0.27
0.62
0.40
Floor (in contact with
complete ground or cellar)
0.7
0.32
0.32
0.40
-
-
-
0.60
5.1
1.8
1.8
2.50
-
-
-
1.60
Floor (in contact with the
exterior environment)
Window
Glass
Table 1
Overview of the transmission loss for the various sections of the building shell
in their initialcondition and the proposals drawn up for improving the insulation.
The maximum U values permitted for individual building sections according to the
current standards are also included in the table (© KIK-IRPA).
decrease in primary consumption.
The uninsulated roof in particular
was a major source of heat loss:
44% of the total heat is lost through
the roof. But the façades (20%) and
windows (28%) were also areas of
large losses. The transmission loss
(U values) for the various sections
of the building shell were far above
the maximum standard values for
new builds (Table 1).
Using these data, a proposal was
drawn up to improve the insulation values of the various building sections by: i) insulating the
façades on the inside; ii) insulating
the roof and floors; and iii) placing
secondary glazing with mobile
awnings in the space between the
protected and the new windows.
Initially a proposal was drawn up
(Solution A) in which the exterior
walls would be insulated on the
inside with a 12 cm thick calcium
silicate board with a plasterwork
finish. This would provide a U value
of 0.26 W/m²K. In this way, the various building sections would meet
the current standard values (Table
1) after adaptation. In a second
phase (Solution B) an alternative
solution for the inside insulation
was put forward using 3 cm thick
insulating plasterwork, which
could provide a U value of 0.62
W/m²K. Insulation on the inside
provides a gain in comparison to
the original situation, although
this does not meet the current
requirements according to the
energy performance regulations.
This would decrease the primary
annual energy consumption from
400 kW/m² to 188 kW/m². The new
K and E levels would become 27
and 81 respectively: a substantial
improvement. However, for the E
level, the energy consumption is
still too high to be able to call it a
nearly energy-neutral office building (i.e. K level lower than or equal
to K40 and E level lower than or
equal to E40).
POTENTIAL BENEFITS
AND RISKS OF IMPROVING
THE INSULATION OF
MONUMENT FAÇADES
In principle, there are three possible scenarios for improving
the façades’ thermal insulation:
floor
6%
cellar wall
4%
cellar wall
2%
windows
28%
roof
windows
3%
cellar wall
roof
12%
floor
10%
roof
44%
façade
22%
windows
40%
façade
28%
floor
cold bridges
9%
roof
façade
windows
roof windows
cold bridges
Fig. 3
Distribution of heat losses to building section according to the initial situation (left) and the situation after improvement
of the insulation according to Solution A (right). (Daidalos, 2011).
exterior insulation, cavity wall
insulation and interior insulation.
Regarding quality and performance, exterior insulation is
without a doubt the best option;
cold bridges are avoided and the
supporting structure is protected
against changes in temperature
and moisture content. However,
because the original façade is
lost, this is often not an option
for listed monuments. If such an
alteration were permitted, this
solution would provide better
protection for valuable interior
elements because the interior
volume is better protected.
Buildings with an uninsulated
cavity wall can be insulated retrospectively. But as cavity walls have
only been used since WWII, this
approach is also often not applicable to monuments. The most common practice for improvement of
the insulation value of monument
façades is therefore the placement
of interior insulation. Interior insulation strengthens the impact of
cold bridges and as a consequence
is less efficient and of course leads
to the loss of the original interior
decoration. Furthermore, this
solution too is not always applicable to historical heritage.
Applying interior insulation to
monument façades also carries
with it risks in terms of keeping the exterior façade intact.
Interior insulation does, after all,
have an impact on temperature
division and moisture balance in
the cross-section of the façade,
particularly when no cavity wall
is present and the façade forms
the direct separation between
the interior and exterior environments. The temperature in simple
brickwork tends to vary gradually
between the interior and exterior
surface (fig. 4a). However, after
applying the interior insulation a
large temperature difference will
occur across the insulation layer,
making the interior surface of
the façade warmer and the parts
of the walls on the exterior of
the insulation layer considerably
colder (fig. 4b and 4c). As a consequence, the depth of influence of
frost on the exterior surface of the
façade increases.
Moisture balance is determined by
the balance between the precipitation on the façade, possible condensation in the wall and the evaporation from both the interior and
exterior surface. Drying is influenced by the temperature division
in the cross-section of the façade.
A higher temperature in the façade
without thermal insulation will
promote drying. Conversely, after
the application of interior insulation the moisture content in the
wall will increase, thus increasing the risks of frost damage
(increased by the decreased temperature near the exterior surface)
and biological attacks to the exterior surface.
There are two ways to insulate
the interior: methods that form
a water- and condensation-tight
layer on the interior surface to keep
out the moisture; and methods
that make use of capillary active
materials. Methods that form a
water- and condensation-tight
layer make use of watertight and
water resistant insulation materials
such as rock wool, polyurethane,
etc. in addition to applying a
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Fig. 4a
Fig. 4b
Fig. 4c
Fig. 4a, 4b and 4c
Overview of the temperature transition
(red curve) and the possibility of
moisture exchange between the
interior and exterior environment
(blue arrow) for non-insulated mass
brickwork (a) and an interior insulated
construction with water and damp
proof insulation material (b) and
capillary-active insulation material (c)
(© KIK-IRPA).
condensation-tight film to the
interior surface in order to prevent
condensation problems. Such a
solution rules out moisture transfer between the wall and the interior (fig. 4b). Drying of the brickwork is thus only possible from
interior to exterior, which results
in an increase in the average moisture content. However, the insulation materials always remain
dry, thus retaining their insulating
qualities. Therefore such a solution is of better quality from a tech-
nical point of view. The increasing
moisture content near the exterior
surface does however increase the
risk of frost damage and biological
attacks. On the other hand, if capillary active insulation materials
are used (such as calcium silicate
boards or insulating plasterwork)
the moisture transfer through the
construction, from the interior to
exterior, is retained (fig. 4c). On
average, this leads to a decrease
in moisture content in the brickwork, thus also decreasing the risk
of damage to the historical façade
elements. This solution is thus the
preferable option for maintaining
heritage property. However, the
fact that the insulation materials
can (temporarily) absorb moisture
and therefore (temporarily) lose
a portion of their insulation value
must be taken into account.
Applying interior insulation to historical buildings with brickwork
façades is thus not without risk.
By insulating the inside walls,
heat loss decreases, causing an
average increase in the moisture
content in the brickwork of the
façade and simultaneously making
it colder. The combination of these
two elements increases the risks
of both frost damage and biological
attack to the façades. Particuarly
when materials are present in the
historical façades which create a
risk of frost damage, taking a good
look at the pros and cons is very
important.
RISK-EVALUATION OF FROST
DAMAGE WHEN APPLYING
INTERIOR INSULATION
TO THE FAÇADE OF THE
VETERINARY SCHOOL
In order to be able to evaluate the
risk of frost damage, the evolution of the temperature and the
moisture content in the veterinary
school’s façades were examined
based on the interior insulation
choice. This approach was based
on the heat and moisture transport
in the façade brickwork as a function
of the interior and exterior climate
and the material characteristics
of the cross-section of the façade.
Material characteristics such as
density Ð, accessible porosity Ð0,
pore division, capillary water
absorption coefficient Acap and
degree of capillary saturation wsat
were experimentally determined
on illuminated samples (table 2).
Absent material characteristics,
such as thermal conductivity Ð
and moisture permeability µ, were
estimated in a rational way based
on known correlations to the other
experimentally determined, material characteristics. A model of the
combination of heat, moisture and
mass transport was created in the
Delphin 5.6 program, developed by
the T.U. Dresden.
This study on the influence of the interior insulation on the temperature
division and the moisture balance in
the façade brickwork concentrated,
firstly on the rear façade and secondly on the façade brickwork
masonry of the front façade, where
the ashlar is made of Euville (table
3). The core of the brickwork, just
behind the ashlar, is also made of
brickwork masonry on the front
façade. The initial situation of
each façade was then compared
with the condition in which interior insulation based on a 12 cm
thick calcium silicate board, and a
3 cm layer of insulated plasterwork,
was used.
The results show the evolution
of the temperature and moisture
content in the cross-section of
the wall over time. The evolution
of the moisture content is shown
in figures 5 and 6, for the rear and
front façade respectively, at each
Euville
Brick
Bricklaying
mortar
Euville grout
Brick grout
Porosity
(vol%)
11
31
24
22
28
Average pore diameter (µm)
6.1
0.56
0.069
0.67
0.60
Density
(kg/m³)
2310
1624
1789
1886
1676
Water absorption coefficient
(kg/m²s0.5)
0.03
0.16
0.03
0.08
0.11
Degree of capillary saturation
(kg/m³)
91
219
103
242
248
Thermal conductivity
(W/mK)
0.7
0.6
0.7
0.7
0.7
Moisture permeability
(-)
56
20
15
5
10
Material characteristic
Table 2
Overzicht van de experimenteel bepaalde materiaaleigenschappen (© KIK-IRPA).
Condition
Front and side façades
Rear façade
Initial condition
Solution A
interior insulation with 12 cm
thick calcium silicate board
Solution B
interior insulation with 3 cm
thick insulated plasterwork
Brick
Euville limestone
Multipor insulation panel
bricklaying mortar
current plasterwork
Multipor adhesive mortar
Volcalite insulated plasterwork
New plasterwork
Table 3
Overview of the different calculation models for analysing the temperature division and moisture balance in the façade
brickwork based on the interior insulation. The exterior wall of the façade is always on the left of the façade cross-section
in the diagram (© KIK-IRPA).
time interval for each of the possible
situations. Figure 7 shows the evolution of the temperature in the front
façade. The simulation was always
performed over a reference period
of several years in order to obtain a
balance of the moisture content in
the wall. The graphs show only the
evolution of the temperature and
the moisture content during the last
year of this reference period. A total
reference period of three years was
sufficient for the façade brickwork
at the rear (the brickwork masonry
only). A reference period of five
years was needed to reach a balance for the brickwork on the front
façade, with the ashlar in Euville
limestone.
The evolution of the moisture content in the façade brickwork shows
considerable differences between
the front and rear façade, and also
between the initial condition and
both interior insulation options.
Periods of heavy rainfall, mainly
in the spring and autumn, can be
easily recognised in the division
of moisture content in the brickwork. The water is absorbed by
the façade via the exterior surface,
which is always shown at the bottom of the graphs. This evolution
is easy to recognise via the change
of colour, from red (dry, 1-2 vol. %
moisture content) to green (wet,
> 10 vol. % moisture content).
Subsequent drying of the brickwork follows the same pattern, but
in the other direction. The analysis
shows that the façade is saturated
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ONLINE
Fig. 5
Evolution of the moisture content in the brickwork of the
rear façade according to their initial condition (a), after
applying interior insulation based on 12 cm thick calcium
silicate board (b), and after applying 3 cm thick insulating
plasterwork layer (c). The scale shows the moisture content
(vol. %) of the total pore volume. The exterior surface is
always shown at the bottom of the graph and the interior
surface at the top. The diagram of the wall cross-section is
shown to the left of the graph (© KIK-IRPA).
Fig. 6
Evolution of the moisture content in the brickwork of the
front façade according to the initial condition (a), after
applying interior insulation based on 12 cm thick calcium
silicate board (b), and after applying 3 cm thick insulating
plasterwork layer (c). The scale shows the moisture content
(vol. %) of the total pore volume. The exterior surface is
always shown at the bottom of the graph and the interior
surface at the top. The diagram of the wall cross-section is
shown to the left of the graph (© KIK-IRPA).
Fig. 7
Evolution of the temperature in the brickwork of the
front façade according to the initial condition (a), after
applying interior insulation based on 12 cm thick
calcium silicate board (b), and after applying 3 cm thick
insulating plasterwork layer (c). The scale shows the
temperature(°C). The exterior surface is always shown at
the bottom of the graph and the interior surface at the top.
The diagram of the wall cross-section is shown to the left
of the graph (© KIK-IRPA).
quite quickly, as the set mortar
behind it greedily draws out water
from the bricks. From there, the
moisture slowly penetrates deeper
into the brickwork.
The comparison of the brickwork
on the front and rear façades
clearly shows that the front façade
is much more susceptible to
absorbing moisture; the rain water
penetrates deeper into the façade
and the moisture content reached
is also much higher. On the front
façade the moisture almost
reaches the interior surface,
while on the rear façade only the
first two layers of the brickwork
become damp. When comparing
the initial condition with the available options for interior insulation,
the 12 cm thick calcium silicate
board receives considerably lower
marks. The core of the brickwork
behind the Euville ashlar is completely saturated all year round.
Even the insulation board itself
is almost completely saturated,
with the exception of the last few
cm of the interior surface, which
can dry inside during winter. The
dampness of the insulation board is
accompanied by a significant loss in
the insulating value of the façade’s
cross-section.
This
condition
deteriorates even more when the
influence of an edge joint from the
exterior surface to the insulation
board is considered. The moisture
quickly penetrates deep into the
façade and dampens the insulation
board locally to the extent that the
joint will inevitably become clearly
visible on the interior surface of
the façade. Therefore, such a solution would be unacceptable without additional measures.
On the other hand, the moisture
balance in the brickwork of the rear
and front façades after application
of insulating plasterwork with a
3 cm layer is not significantly different to the initial condition.
The evolution of the moisture content in the façade’s cross-section
must also be assessed in combination with the temperature division.
The front façade is shown in figure 7.
At first glance, the temperature division according to the three available
alternatives (i.e. the initial condition
and both options for improvement of
the insulation) appear quite similar. Only the depth to which cold
temperatures penetrate the façade
increases visibly with an increasing insulating value. This can
be recognised by the increasing
amount of green and blue colours
in the temperature division after
application of interior insulation.
The increasing temperature drop
throughout the entire cross-section
of the façade is particularly recognisable when opting for a 12 cm thick
calcium silicate board.
Based on these results, the number
of frost-thaw cycles to the exterior
façade were compared to the number of times the moisture content in
this zone was higher than 30%, 50%
and 70% respectively of the saturation degree of the Euville limestone
(table 4) to evaluate the risk of frost
Condition
damage to the front façade. The
critical moisture content causing
frost damage to the Euville limestone is however unknown, therefore these moisture contents are
purely arbitrary. The results clearly
demonstrate the influence of the
application of an insulating calcium silicate board to the interior
surface: the number of cycles in
which frost occurs while the Euville
limestone is wet increases significantly (+230% at w > 30% wkr). The
situation is less dramatic when
applying a thin layer of insulating
plasterwork. A slight increase
(+50% at w > 30% wkr) in critical
frost-thaw cycles can be observed.
Exposure of facing brick to frostthaw cycles does not necessarily lead to damage. The degree of
sensitivity or resistance to frost
of the facing brick in question is
the determining factor here. The
previous Belgian standard, NBN
B27-010, used the Gc criterion for
this. Although the applicability of
this criterion has been questioned
and certainly cannot be applied to
all materials, it can still serve as a
first indication when assessing the
Number of
Number of frost-thaw cycles at which
frost-thaw cycles the moisture content is higher than
30% of
50% of
70% of
wsat
wsat
wsat
Initial condition
61
13
4
2
Solution A
interior insulation
with 12 cm thick
calcium silicate board
67
30
9
6
Solution B
interior insulation
with 3 cm thick
insulated plasterwork
65
19
5
3
Table 4
Overview of the number of frost-thaw cycles and the number of critical frost-thaw
cycles at which the moisture content in the brickwork of the front façade is higher
than the set limits (© KIK-IRPA).
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ONLINE
risk for frost damage. The Gc factor
is calculated using the following
formula:
Gc = -14.53 - 0.309 α + 0.203 S
Where α is the water absorption coefficient of the material,
expressed as saturation percentage per time unit in s0.5, and
S the water accessible porosity,
expressed as a percentage of the
total volume. The experimentally
determined Gc values based on the
illuminated samples are recorded
in Table 5. The standard dictates
that the Gc value for vertical façade
elements in solid brickwork must
be less than -1 and less than -2.5
for horizontal façade elements.
Therefore, depending on the exact
value, both the joint mortars and
the façade parts in Euville display
a possible risk of frost damage
according to the aforementioned
criterion. Take note that Euville
limestone is generally considered
to be frost resistant and that the
WTCB is more likely to list guideline values between -4.4 and -5.5
for the Gc factor. The Euville limestone results are more varied,
which may indicate the use of lesser-quality materials , leading to a
risk of local frost damage.
It is important to note that for the
evaluation of the materials’ sensitivity to frost, only possible frost
damage to the materials is taken
into account. Damage resulting
from the combination of materials in the masonry, such as a joint
being pushed outwards for example, is not taken into account in this
criterion.
CONCLUSION
The evaluation of the available
options to improve the insulating
quality of the exterior façades of
Material
Euville limestone
Gc factor
-3.42 to 0.28
Brick
-1.66
Bricklaying
mortar
-6.96
Grout Euville
limestone
-0.33
Grout brick
-0.64
Table 5
Overview of the experimentally
determined Gc factor for the various
façade materials (© KIK-IRPA).
the former veterinary school in
Anderlecht shows that the risks
of possible frost damage to the
façade’s brickwork increase significantly, particularly to the front
and side façades, which have
an ashlar in Euville limestone,
and to a lesser extent to the rear
façade, which is mainly brickwork.
Therefore, the construction of the
historical brickwork has an important influence on temperature
division, moisture content and the
accompanying risk of frost damage to the ashlar, regardless of the
type of interior insulation.
The initial decision to reduce the
primary energy consumption of the
building from approx. 400 kW/m²
to 188 kW/m² by improving the
insulation to the shell of the building entailed the application of a
12 cm thick insulation board based
on calcium silicate to the interior surface of the exterior walls.
The study shows that this type
of approach leads to a marked
increase in the risk of frost damage to the ashlar, particularly to
the façade sections in Euville limestone, which are already sensitive to
moisture. Moreover, there is a risk of
edge joints becoming clearly visible
on the interior surface, caused by
water transfer through the joint and
the insulation board. A 3 cm thick
layer of insulating plasterwork,
resulting in a somewhat higher
energy loss through the exterior
walls, allows for a substantial gain
– in terms of possible frost damage – in comparison to the original
proposal for improvement of the
insulation. An increase in the risk
of frost damage in comparison
to the current situation remains,
though it is less significant.
To assess the actual risks of frost
damage, the Gc criterion for the
materials according to an old
Belgian standard was compared to
on-site observations of the damage.
An evaluation of the sections of
the front and side façades showed
considerable damage to the limestone (fig. 8). However, the primary
cause of the observed damage to
the Euville limestone has more to
do with the formation of gypsum as
a result of air pollution than with
frost damage. This in and of itself
confirms the general assessment
of Euville as a frost-resistant limestone. The formation of the gypsum
crust does however influence the
pore structure close to the stone’s
surface, thus increasing the risk of
frost damage over time. Therefore,
totally eliminating the risk of frost
damage is impossible.
The possible risks are, however,
connected to the amount of rain
which penetrates the wall. It is
above all the uppermost sections of the walls (which are more
exposed to rain) that are particularly susceptible to this. Based on
the study, the decision was made
to diversify the application of interior insulation: on the ground floor
and first floor it was opted to follow the original proposal and apply
insulation, namely 12 cm thick
calcium silicate boards. On the top
floors, 8 cm thick calcium silicate
boards would be used, thus countering the increased risk of frost
damage. The permeation of moisture through the horizontal joints
was countered by using suitable
interior finishings.
Visual inspection of the rear façade
shows that, in spite of the limited
risk of frost damage according to
the results of the modelling and
the general assessment of the
materials as being not or only
slightly sensitive to frost, frost
damage appears frequently (fig. 9).
Fig. 8
Overview of the damage to
the Euville limestone front façade
of the main administrative building
of the veterinary school
(photo by author).
The brickwork’s sensitivity to frost
as a whole is therefore substantially more important than might
be expected based on the Gc criterion, which only allows for an
assessment of the individual materials. The jointing in particular can
be described as highly sensitive to
frost. Appropriate selection of new
grout and minimum interior insulation using insulating plasterwork
are therefore recommended for
obtaining an acceptable level for
the risks of frost damage.
Fig. 9
Overview of the damage to the brickwork rear façade
of the main administrative building of the veterinary school (photo by author).
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REFERENCES
ARTER, École vétérinaire d’Anderlecht,
Phase 3: Restauration extérieure des
façades et toitures, Notes historiques,
December 2012, p. 12
Bogaerts Philippe, La médecine
vétérinaire en Belgique,
http://www.ping.be/~ping0522/
Histoire.html, consulted on
6 February 2015
Daidalos-Peutz, Renovatie van
de oude veeartsenarijschool te
Anderlecht in een laag energie kantoor,
Energetische haalbaarheidsstudie
VETO, 1 March 2011, p. 6
Wikipedia, Claude Bourgelat,
http://fr.wikipedia.org/wiki/
Claude_Bourgelat, consulted on
6 February 2015
Analyse des risques de
l’application de l’isolation
intérieure dans des bâtiments
historiques : l’étude de cas de
l’ancienne école vétérinaire à
Anderlecht
La revalorisation des bâtiments
historiques génère souvent une
demande d’isolation plus efficace
de leur enveloppe, surtout en
cette époque où l’énergie coûte
cher et où les valeurs écologiques
s’imposent. Cela dit, il n’est pas
facile de renforcer l’isolation d’un
bâtiment historique sans toucher
à ses qualités patrimoniales.
Les façades monumentales,
en effet, limitent généralement
la possibilité d’améliorer
leur isolation par l’extérieur.
L’isolation intérieure constitue
souvent la seule possibilité.
Mais les interventions de ce type
influencent aussi la gestion de
l’humidité dans toute la coupe de
la façade, en augmentant parfois
substantiellement les risques de
dégâts du gel dans les matériaux
de façade.
Les restrictions et les risques
inhérents à ce genre de travaux
sont exposés dans le contexte
de l’ancienne école vétérinaire
d’Anderlecht : l’application de
l’isolant intérieur est évaluée du
point de vue de la protection des
façades monumentales en brique,
pierre d’Euville et pierre bleue.
Risico-analyse van de toepassing
van binnenisolatie in historische
gebouwen : case study, de
voormalige veeartsenijschool te
Anderlecht
De herwaardering van historische
gebouwen leidt vaak tot een vraag
naar een betere isolatie van de
gebouwschil, zeker in tijden van
hoge energieprijzen en verhoogd
besef van ecologische waarden.
Echter, een verbetering van de
isolatie van een historisch gebouw
is zelden evident, zeker zonder
daarbij afbreuk te doen aan zijn
erfgoedwaarden. De gevelpartijen
van monumenten beperken
immers vaak de mogelijkheid om
de isolatiewaarde van een gevel
langs de buitenzijde te verhogen.
Het aanbrengen van binnenisolatie
is vaak de enige mogelijkheid.
Een dergelijke ingreep beïnvloedt
evenwel de vochthuishouding
van de gehele geveldoorsnede,
met soms een substantiële
verhoging van het risico op
onder meer vorstschade aan de
gevelmaterialen.
De beperkingen en risico’s inherent
aan een dergelijke ingreep worden
toegelicht aan de hand van de
voormalige veeartsenijschool
te Anderlecht, waarbij de
toepassing van binnenisolatie
wordt geëvalueerd ten overstaan
van de bescherming van de
monumentgevels in baksteen,
Euville en blauwe hardsteen.
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IEDER ZIJN HUIS: THE RENOVATION OF A
MODERNIST SOCIAL HOUSING TOWER BLOCK
CHARLOTTE NYS
ORIGIN ARCHITECTURE & ENGINEERING
THE RENOVATION PROJECT OF THE IEDER ZIJN HUIS SOCIAL TOWER BLOCK
COMPLIES WITH CURRENT REQUIREMENTS REGARDING INSULATION, COMFORT,
FIRE SAFETY, ACOUSTICS AND SAFETY, WHILE AT THE SAME TIME TAKING
INTO ACCOUNT THE CHARACTERISTICS OF THE BUILDING, ITS LAYOUT AND
ORGANISATION, DESIGN AND ARCHITECTURAL LOGIC. THE RESOURCES USED
AND THE RESULTS OF THIS AMBITIOUS OPERATION, WHICH INCLUDED PROBLEMS
REGARDING HOUSING, ECONOMICS, ENERGY AND HERITAGE, ARE PRESENTED HERE.
The following contribution is a presentation of the renovation project of
the Ieder Zijn Huis modernist tower
block in Evere. Through Beliris, the
federal government has undertaken
to renovate this building. Beliris
determined the general building
programme, including the important principle that the homes must
comply with current regulations, in
particular the Energy Performance
of Buildings (EBP) regulations.
This had to be done with the necessary respect for and/or conservation of this heritage’s characteristics. For this project the building
history research was carried out
by Ghent University, the building
physics and acoustics were studied
by Daidalos Peutz, the techniques
were studied by Marcq en Roba
and the stability and architecture
by Origin.
Belgium has an exceptionally
rich and extensive heritage when
it comes to social (i.e. govern-
ment-assisted) housing. The construction of social housing has
played an active role in the history
of our Belgian architecture.
Pictured are two garden city buildings (fig. 1 and 2) and two tower
blocks (fig. 3 and 4). This recent
heritage was built between the
1920s and the 1970s. The difficulty with these homes is that they
often do not achieve current comfort requirements or comply with
EPB regulations. Heritage buildings are all too often in a terribly
dilapidated state. They are mostly
unlisted, which means that this
valuable heritage is in danger of
being lost.
Ieder Zijn Huis is located in Evere.
A defining feature of this building
is that the tower is long, narrow
and high: 9 m wide, 90 m long
and 50 m high. In 1954, Willy
Van Der Meeren received the
design commission from mayor
76 | Ieder Zijn Huis: the renovation of a modernist social housing tower block
Franz Guillaume, a socialist who
was very interested in this type of
residence. Initially, Le Corbusier
had been asked to build this tower
block. When he declined, Franz
Guillaume turned to Willy Van Der
Meeren. There were two calls for
tenders because the initial price
was too high. Construction began
in 1959 and the building was delivered in 1961.
WILLY VAN DER MEEREN
AND HIS CONSTRUCTION
PRINCIPLES
Willy Van Der Meeren was born in
1923 and died in 2002. He trained
as an architect at the La Cambre
modernist school of architecture.
Van Der Meeren is best known
for the CECA house, which he
designed together with Leon Palm
as a solution to the acute housing
shortage at that time. It was an
inexpensive labourer’s cottage that
Fig. 1
Le Logis and Foréal, Watermaal-Bosvoorde
(A. de Ville de Goyet © GOB).
Fig. 2
De Moderne Wijk, Samenwerkersplein,
Sint-Agatha-Berchem (© Origin).
Fig. 3
Modelwijk, Laken (A. de Ville de Goyet © GOB).
Fig. 4
Ieder Zijn Huis, Evere. The east façade, almost completely
renovated (© G. De Kinder).
made extensive use of modulation
and standardisation. Furthermore,
Van Der Meeren should be viewed
as a total-concept designer.
Before discussing the renovation, it is important to identify and
acknowledge the characteristics
of this building. The characteristics have been grouped into eight
themes:
The first characteristic is that the
building very clearly illustrates
“new communal living principles”.
It is a high-rise building. Willy Van
Der Meeren described his building
as “streets in the sky”, as can be
seen in figure 5 as well as in the
cross-section (fig. 6). He designed
wide circulation corridors which
can be found on every third floor.
This gave people the chance to meet
one another, thus emphasising
the “streets in the sky” concept.
The advantage here is that the
apartments span from façade to
façade, which allows natural light
to saturate the homes. The roof
terrace is typical of that period,
along with a large variety of public
functions and collective facilities,
such as a mortuary, a relaxation
room and a laundry room.
as the predecessor to open-plan
living. He also wanted to integrate
an open kitchen, but the time was
not yet ripe.
A second characteristic: “the ideas
about modern living”. The building
is built on stilts. All of the homes
receive a great deal of natural
light, which Van Der Meeren
achieved by bringing in diagonal
light. The homes could be seen
The following characteristic is “the
hierarchical construction of plan
and façade”. In other words, the
façade is a translation of the plan
behind it. For example, the bedrooms have three windows at the
top of the wall, the kitchens have
Another characteristic: “simple
and affordable”. Van Der Meeren
created a type of Meccano system
with doorways of reinforced concrete supporting the arches. The
entirety was sealed using façade
panels and all that was left to do
was to add a layer of paint.
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ONLINE
Fig. 5
Stairwell (© G. De Kinder).
Fig. 6
Cross-section illustrating the division
principle of the apartments
(© Willy Van Der Meeren Archives).
Fig. 7
Entrance door to apartments
(© G. De Kinder).
Fig. 8
Entrance hall with mailboxes and fresco by Jo Delahaut
(© Willy Van Der Meeren Archives).
Fig. 9
Staircase with access to the apartments.
The colour was retained. (© G. De Kinder).
Fig. 10
Here, a typical Willy Van Der Meeren touch: the tap can be
used for both the bathtub and the sink (© K. Verswijver).
Fig. 11
Living room. The height from the finished floor to the lower side
of the arches is exactly 2.5 m. The measured height between the
bottom of the doorways and the finished floor is 2 m (© Origin).
a terrace, the living rooms have
windows both at the top and at the
bottom of the wall. Van Der Meeren
uses functional architecture which
he brings to life with the use of art
and colour (fig. 7, 8 and 9).
The final three characteristics typical of Van Der Meeren are “modulation”, “prefabrication” and
“standardisation”. These relate to
the intensive use of modulation in
order to make prefabrication and
standardisation possible. For this
he used the Modulor. Even the
arches are custom made with a
width of 57.5 cm, or half a module.
CONDITION OF THE BUILDING
UPON START OF WORKS
The first problem, and one of the
most significant, was linked to the
building physics. According to information received from the Housing
Association, for the majority of the
residents energy costs were higher
than rental costs. The façade was
built using sandwich panels - 5 cm
concrete on the exterior and 5 cm
concrete on the interior with a thin
2 cm insulation layer in between
- and thus had very limited thermal resistance. The façade panels
were hung up in the structure; as a
result the structure runs from the
interior to the exterior in the façade
and large thermal cold bridges are
created via the structure.
A second difficulty in the building
was fire safety. According to the
letter of the law there are too few
emergency staircases because
they are placed 57 m from each
other (it should be 60 m). There
was also no compartmenting
between the emergency staircases
and the lifts, thus (as a high-rise
building) both had to be equipped
with an airlock. Some apartments
had direct access to the stairwells.
The apartments are not compartmented in regard to circulation
and the structure does not have a
fire resistance of two hours, which
in this case applies to the arches
above all. The final important
point is that the fire spread criterion in the façade is insufficient.
Normally, there must be a zone
with a development of one metre in
length and a fire resistance of one
hour, both between two floors and
between two apartments (i.e. both
horizontally and vertically).
In addition, the technical installations were antiquated. There was
no ventilation system installed into
the building. The acoustic problems are obvious when considering
the construction method: problems
with noise transfer via the communal technical shafts; problems
with contact noise throughout the
entire structure; far too few absorbent surfaces; and too little mass
between adjoining apartments.
A final problem was the very limited
height of the apartments. In figure
11 you can see that the height from
the finished floor to the bottom
of the arches is exactly 2.5 m.
The measured height between
the bottom of the doorways and
the finished floor is 2 m. There
is therefore very little room for
providing technical or other
equipment as the screed is only
7 cm thick and is located on the
arches. The screeds and the arches
do not work together, making the
screed extra weigh on the arches.
In order to gain a more in-depth
knowledge of the construction
and condition of the tower block,
a series of probes, prototypes and
mockups were carried out. These
included dismantling a façade
panel to see just how that panel was
installed, whether it was easy to
dismantle and to better understand
the panel’s composition. Research
into the condition of the concrete
was carried out (there is quite a
lot of visible concrete present).
The composition of the roof, the
floors and the existing brickwork
were examined. Additional research
was carried out regarding the fire
safety of the stairs and additional
measurements taken relating to the
structure of the entire building to
determine the correct dimensions of
the façade panelling. Many acoustic
measurements were taken as this
was an important factor in living
comfort. Research into the building’s
lateral stability was also needed.
The most important themes for the
renovation philosophy of the project
were as follows: to design a comfortable layout for the apartments
with a particular focus on the communal spaces and a façade that
meets the EPB requirements, all
achieved with respect for the characteristics summarised above.
THE PROGRAMME
The building originally consisted
of 105 homes. They have since
been turned into 103 apartments,
and to optimise living comfort all
of the three-bedroom apartments
were converted into two-bedroom
apartments. Regarding energy
performance, the result is a global
K level of K30 and an E level of E80
per home. To improve acoustics
and fire safety, all floors and
ceilings were fitted with insulating
acoustic materials. This caused
the loss of the building’s internal
thermal inertia. Despite the
brand new façade, overheating
in the summer period remained
a problem. Due to this, a number
of windows had to be sacrificed,
mainly in the bedrooms. Exterior
sun protection was also placed on
every top window.
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For the façades an extensive range
of solutions was examined. Firstly,
the possibility of keeping the existing façade was explored, but this
was very difficult to justify in terms
of energy performance. Installing
a new skin in front of the old skin
could not be justified in terms of
heritage, particularly as the building is built on stilts.
Another idea was a metal structure
with integrated windows as a new
type of prefab system, finished with
insulation and a type of plaster.
This solution deviated too greatly
from the project and gave nearly
no thermal inertia to the building.
Finally, the architects went back to
the idea of using concrete prefab
elements again, but this time
with a new prefab element that
completely covered the structure,
thus avoiding cold bridge problems
- either at floor level or around the
columns - and with the following
element: 12 cm concrete on the
interior, 15 cm polyurethane
insulation and then 7 cm concrete
on the exterior.
Regarding the design for the
façade, Willy Van Der Meeren’s
concept was used again, including
the same design parameters.
Two additional parameters were
added in order to determine
the design: on the one hand fire
safety and on the other energy
performance (fig. 13 and 14). In
this concept, the outermost arch
was first dismantled and a new
beam installed on which the new
façade could be hung. In order to
solve the fire safety problem of
the new façade, a type of nosing
was integrated into the façade.
The developing length measured
at one metre. This solves the fire
spread problems and means that
it is still possible to integrate a fair
number of windows.
Fig. 12a
Fig. 12b
Fig. 12c
Fig. 12a, 12b and 12c
12a: original building by Willy Van Der Meeren
(© Willy van der Meeren Archives). 12b: the building before
renovation; showing the brick stair shafts covered due to
water infiltration. They were equipped with a metal cover
long ago (© G. De Kinder). 12c: a drawing of the final
project (© Origin).
Fig. 13
Sandwich panel principle (© Origin).
Fig. 14
Assembly sketch (© Origin).
Fig. 15
Current situation (© Origin).
Fig. 16
Detail of a concrete panel (© Origin).
To meet the fire spread criteria
horizontally as well as vertically,
one fewer window was placed
between every two apartments. A
few photos of the façade panel are
included for illustrative purposes:
figure 15 shows the original
situation and figure 16 shows the
new façade panel installed in front
of the structure.
In addition to the façade, all of the
terraces were replaced. For each
terrace, an arch was dismantled
and replaced with a new prefab
element through which the
concrete nosing runs. That prefab
element was then connected to the
structure with a thermal breaker so
that no cold bridges were created
along the terraces.
The manner in which the façade
insulation was integrated is
interesting. The building is, after
all, built on stilts and the floor
above the stilts has a brick façade
with storage rooms and a large
shaft for technical pipes and cables
behind it. It was decided during the
design process not to insulate this
brick façade. The insulated volume
includes the roof and the façade
elements and runs along the top
of the storage area and around the
technical shaft.
The internal geometry was hardly
altered. The arches were retained,
except for the first arch along the
façade, which was necessary for
placing the façade panel. The screed
was completely dismantled in order
to make room for a new, independent
floor complex so that no contact
noise can be transferred via the
structure. For reasons of fire safety,
a lowered ceiling was placed in direct
contact with the arches; this also
proved beneficial to the acoustics.
As mentioned earlier, the layout has
a diagonal working to bring in light.
The new layout is very similar to the
original concept. The bathrooms and
kitchens were changed slightly, but
the interior stairs were kept. The
compartmenting was improved as
the lift airlocks and stairwells were
separated by automatic fire doors.
All of the railings have been adapted
in some way. In the new façade,
windows have disappeared in some
places in order to solve the problems
of overheating and fire spread.
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IZH TOWER BLOCK RENOVATION COSTS
Surface, gross
12,150 m2
ESTIMATE
PROCUREMENT
excl. VAT
FINAL COST
excl. VAT
excl. VAT
SITE INSTALLATION
EUR 1,039,725
EUR 86/m²
7%
EUR 1,245,251
EUR 102/m²
10%
EUR 1,230,932
EUR 101/m²
9%
DEMOLITION
EUR 1,147,472
EUR 94/m²
8%
EUR 442,531
EUR 36/m²
4%
EUR 501,592
EUR 41/m²
4%
ROOFING
EUR 170,529
EUR 14/m²
1%
EUR 139,956
EUR 12/m²
1%
EUR 139,011
EUR 11/m²
1%
FAÇADES
EUR 4,367,039
EUR 359/m²
29%
EUR 4,095,999
EUR 337/m²
34%
EUR 4,379,440
EUR 360/m²
34%
EUR 894,380
EUR 74/m²
6%
EUR 930,894
EUR 77/m²
8%
EUR 1,223,677
EUR 101/m²
9%
INTERIOR FIXTURES
EUR 4,243,412
EUR 349/m²
28%
EUR 2,945,457
EUR 242/m²
24%
EUR 3,036,695
EUR 250/m²
23%
TECHNICAL EQUIPMENT
EUR 3,327,623
EUR 274/m²
22%
EUR 2,405,123
EUR 198/m²
20%
EUR 2,496,867
EUR 206/m²
19%
SHELL COSTS
TOTAL
EUR 15,190,180 EUR 1,250/m² 100%
EUR 12,205,212 EUR 1,005/m² 100%
A FEW FIGURES
CONCLUSION
During the study we estimated the
costs for works at EUR 1,250 m²
(gross surface area excluding VAT).
At the time of the procurement the
price came in at approximately
EUR 1,000/m², and the final price
including all additional works was
EUR 1,100/m². The largest portion
went on the façade (35% of the
total cost price), while the technical costs amounted to just 20% of
the total cost price. These figures
are not yet definitive as delivery is
not until January (2015).
The character of the renovation
interventions is largely determined
by the manner and strictness
in which heritage is viewed. An
important question in this regard
is what takes priority: the original
concept; the original material; or
both? In this project, we primarily
prioritised the original concept and
then “irreparably improved it”, as
the Dutch architect Maarten Fritz
puts it; an apparent paradox that
is arguably most applicable to this
type of building.
EUR 13,008,215 EUR 1,071/m² 100%
Fig. 17 and 18
Original construction of the building and the current site. In this case a level with apartments from façade to façade.
These floors were completely dismantled. At the “streets in the sky” levels, the complete finish of the circulation corridors
was retained (right: © Willy Van Der Meeren Archives; left: © G. de Kinder).
Fig. 19
Making the prefab elements with the window panes
immediately integrated into the elements. During
assembly, projecting reinforcements were provided
so that, after pouring the concrete floor, they could be
placed as a whole (© Origin).
Fig. 20
Assembly of the new terraces in prefab concrete.
The exterior of the stairwells was insulated with a system of
prefab elements with insulation and brick panels fixed onto
large elements of the bearing structure of the original well
(© Origin).
Fig. 21
Many samples were taken and tests carried out to ensure
the airtightness of the various walls (© Origin).
Fig. 22
The stairs, not yet finished. During the works, it was
decided to treat them with a fire retardant paint for fire
stability. These stairs turned out to have a thin, wooden
stringer (© Origin).
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Ieder Zijn Huis: la rénovation d’une
tour d’habitations sociale
Ieder Zijn Huis: renovatie van een
modernistische woontoren
Le projet de rénovation de la
tour Ieder zijn Huis a eu pour
ambition de répondre aux normes
actuelles d’isolation, de confort, de
protection incendie, d’acoustique
et de sécurité dans le périmètre
des qualités de l’immeuble, de
son plan, de sa distribution, de sa
forme et logique architecturale.
L’élément le plus symbolique
de la tour, mais aussi le plus
problématique, fut la façade,
avec ses panneaux sandwichs en
béton préfabriqué. Ces panneaux
résument à eux seuls la logique
du projet et du concepteur : la
standardisation à outrance, dans
des dimensions et une composition
inspirés des principes du modulor,
la préfabrication en série d’une
manière quasi industrielle, le
gros oeuvre qui coïncide avec la
situation achevée, l’implantation
ludique et abstraite des fenêtres,
offrant une lumière et une vue
optimales, tant pour les enfants
que pour les adultes. Le projet
de rénovation prévoyait de
reconstituer la façade selon sa
logique, sa forme et sa matérialité
à l’aide d’un nouveau panneau
sandwich en béton, préfabriqué
selon la technologie actuelle et
dans le respect des normes en
vigueur aujourd’hui. Les moyens
mis en œuvre pour réaliser ce
projet ainsi que les résultats de
cette opération de grande ampleur,
croisant des problématiques de
logement, d’économie, d’énergie et
d’architecture, seront présentés ici.
De ambitie van het
renovatieproject ‘Ieder zijn Huis’
bestaat erin om de huidige
normen inzake isolatie, comfort,
brandveiligheid, akoestiek en
veiligheid te realiseren binnen
de krijtlijnen van de kwaliteiten
van het gebouw, de planopbouw
en organisatie, vormgeving
en constructieve logica. Het
meest exemplarische maar
ook problematische element
van de toren is de gevelopbouw
met geprefabriceerde betonnen
sandwichpanelen. In deze panelen
wordt de logica van het project
en de ontwerper samengevat in
één element: de doorgedreven
standaardisering met maatgeving
en compositie volgens de principes
van de modulor, prefabricatie in
serie op quasi industriële wijze,
de ruwbouw die samenvalt met
de afgewerkte situatie, de speelse
en abstracte inplanting van de
ramen met maximale lichtinval
en een optimaal zicht, zowel voor
de kinderen als de volwassenen.
In het renovatieproject wordt
ervoor gekozen om de gevel in zijn
logica, vormgeving en materialiteit
te reconstrueren in een nieuw
betonnen sandwichpaneel,
geprefabriceerd volgens de
huidige technologie en de thans
geldende normen. De middelen
die voor de realisatie van dit
project werden ingezet en de
resultaten van deze grootschalige
ingreep, die rekening moest
houden met problematieken van
huisvesting, besparingen, energie
en architectuur, worden hier
gepresenteerd.
85
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THE BRUNFAUT TOWER
PRESENTATION OF THE CONCEPTUAL DESIGN
CHALLENGES OF A RENOVATION
VINCENT DEGRUNE
ARCHITECT/ENGINEER, MUNICIPALITY OF MOLENBEEK-SAINT-JEAN
THIS CASE STUDY RAISES THE QUESTION OF THE FUTURE OF TOWER BLOCKS,
THE HERITAGE VALUE OF WHICH IS, AT FIRST GLANCE, NOT IMMEDIATELY EVIDENT.
MANY EXAMPLES OF SUCH CURRENTLY UNFASHIONABLE BUILDINGS ARE TODAY
THREATENED WITH DEMOLITION, AND NOT JUST IN BRUSSELS. FACED WITH THIS
POSSIBILITY, THE MUNICIPALITY OF MOLENBEEK-SAINT-JEAN COMMISSIONED
THE PARISIAN ARCHITECTURAL FIRM LACATON-VASSAL & DRUOT TO CONDUCT
A CONCEPTUAL DESIGN STUDY TO ASSESS THE IMPACT AND FEASIBILITY OF
VARIOUS RENOVATION OPTIONS.
I have been fascinated by this project to renovate the Brunfaut tower
(fig. 1) and the issues raised by the
project for more than four years.
However, the work has yielded
more questions than answers,
which is probably a very good
thing. My presentation is not overly
technical but rather aims to extend
the notion of heritage to culture,
and that of energy performance to
sustainability.
The Brunfaut tower was not lucky
enough to have been designed by
a famous architect; it was little
known architect, J. Roggen and
his consulting engineer, M. Van
Wetter, who designed the building.
The absence of such renown has
probably contributed to the critical, even malicious, way in which
the structure is viewed today. It
is referred to as the kartonenblok
or “cardboard box” in the neighbourhood. The building is thus
perceived as a symbol of an era
when people were punished by
being piled on top of each other
in office buildings. We have tried
to immerse ourselves in the context in which it was built, which
is important when talking about
heritage. The Brunfaut tower was
built in 1966. At that time, the
ideal of modernity had to some
degree arrived in Belgium (and in
Brussels in particular), but some
twenty or thirty years behind the
United States and France. These
countries had been building based
on the Corbusian model since the
end of the war, with the strong,
simple idea that high-rise construction would provide a solution
both to urban sprawl and the preservation of ground space. Today,
the issue of tower blocks has
arisen again, but it seems that we
are no longer concerned about the
second notion, even though the two
are inextricably linked.
The 1960s were also a period of
great enthusiasm with regard to
mobility. For example, the Leopold II
86 | The Brunfaut tower. Presentation of the conceptual design challenges of a renovation.
viaduct was built to link the Expo ’58
site to the city centre (fig. 2). This
structure was subsequently dismantled and rebuilt in Bangkok, where it
has recently been renovated. This
pretty amazing example of reuse
took a completely ground-breaking
approach to recycling.
A newspaper article from 9th
October 1966 was very useful
in helping us to understand the
extremely innovative and ambitious nature of the tower, not only
from a technical but also a social
perspective, as its construction
was aimed at effectively addressing problems with hygiene in this
“inner suburb” of Brussels. The
construction process was also
described in the article. It can be
seen that the building was completed in less than eight months,
with an extraordinarily sparing use
of resources and materials. Today,
a culture of performance predominates, whereas fifty years ago it
was a culture of efficiency that
took precedence: intervention was
minor, fast and economical. The
difference in approach changes a
lot of things.
BACKGROUND TO
THE TOWER’S RENOVATION
In 2009, the municipality of
Molenbeek-Saint-Jean enjoyed the
benefit of a new neighbourhood contract. The programme provides for
the construction of around twenty
passive homes in accordance with
the decision taken by the municipality in 2007 to apply the passive
standard to all its new buildings
(fig. 3). These buildings were to
be at the base of the tower which
could not itself be renovated as
part of the neighbourhood contract
because such programmes are not
generally intended for buildings
owned by social housing companies. We could not, therefore, in
principle, take action. However, we
noted that the Molenbeek Social
Housing Company had been concerned about what to do with the
tower for several years. The standard two options presented themselves: renovation or demolition/
reconstruction, with the second
option being strongly favoured. At
our request, the Brussels-Capital
Region agreed to a feasibility study
being carried out, as part of the
neighbourhood contract, to answer
the simple question of whether or
not to keep the tower.
This study was to be carried out in
four phases, namely: a technical
assessment; an analysis of
options for restoration (renovation
or demolition/reconstruction); the
restoration programme itself;
and a final report which could be
added to the specifications for the
architectural competition. After
receiving tenders from three teams,
the study was eventually awarded
to the Paris-based architectural
firm Lacaton-Vassal & Druot.
A few years before, the same firm
had authored a work entitled Plus¹
which examined the merits of
demolishing social housing tower
blocks in the Paris suburbs. The
firm had been shocked by the
media coverage of the dynamiting
of the towers which dramatically
collapsed in front of a clapping
audience which was most likely
Fig. 2
Léopold II viaduct. Constructed in 1957, it was
dismantled in 1984 and rebuilt in Bangkok in 1988
(Thai-Belgian-Bridge) (old postcard).
Fig. 1
The Brunfaut tower
(© K. Deruyter).
Fig. 3
Belle-Vue cinema neighbourhood contract
(© municipality of Molenbeek-Saint-Jean)
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2 STAIRWAYS
2 LIFTS
Fig. 4 and 5
Plans of the Brunfaut tower. A simple efficient layout combined with optimal use
of materials (© Lacaton & Vassal).
not made up of residents of the
apartments. The underlying
theme of this work is “that one
must never demolish, take away
or replace, but protect, add,
transform and use”. It is therefore
heritage writ large, consisting of
working on what’s already there,
adding value to it and developing
its qualities.
The architectural firm led us to
look at the tower in a different way,
appreciating that while it was relatively unremarkable architecturally, it possessed a great number
of qualities and its faults could be
significantly reduced by carrying
out work on the envelope. Their
work drew our attention to the fact
that even though the appearance of
the building fell out of favour over
time, it nevertheless possessed
values worth conserving.
THE COURSE OF
THE FEASIBILITY STUDY
The first phase of the study therefore involved listing the qualities of
the building. Anne Lacaton firstly
showed us that the tower was
similar to many others visible in
Chicago, Detroit, Copenhagen and
other cities, built by renowned
architects such as Mies Van der
Rohe or Arne Jacobsen, and that
those towers were clearly not lacking in elegance.
She next drew our attention to
questions of common sense
and to the incredible efficiency
evident in the Brunfaut tower,
such as, for example: the layouts reduced to their most basic
form; a central concrete core with
a spiral staircase at each end;
incredibly sparing use of materi-
als and a lot of subtlety (fig. 4 and
5). Efficiency is in evidence again
with regard to the building’s footprint: 380 m² for 242 inhabitants.
This building therefore provided
great service to numerous families over fifty years. Actual energy
consumption figures (provided by
the Foyer Molenbeekois) are quite
surprising: 179 kWh/m²/year,
which corresponds to around
38 euros/month/apartment of
heating costs for rent that varies
between 175 and 324 euros/month.
These figures are very reasonable
when compared with other buildings of the same period, due, in
particular, to the extreme compactness of the building. However,
there must certainly be a lack of
comfort linked to the total absence
of any insulation in the external
walls. The same efficiency can be
found in the design which displays
obvious architectural qualities: the
apartments are bright, with a window in each room (including the
kitchen and bathroom) and wide
views over the city (fig. 6 to 12).
At the same time, the municipality
of Molenbeek -Saint-Jean was faced
with the problem of a rapidly growing
population which had to be urgently
tackled. The conclusion was as
follows: a lot of new residents were
going to have to find housing within
the municipality’s territory and the
public housing waiting lists were
already swamped (this is still the
case today). Anne Lacaton asked
us how we planned to manage the
situation with the residents if the
demolition/reconstruction option
was chosen. The solution envisaged
at the time by the public authorities
was the usual “temporary relocation”
operation which consists of housing
people elsewhere and bringing
them back once the building has
been renovated. She queried this
practice since the residents of the
tower were going to take the place of
other tenants on the housing waiting
list, forcing them to have to wait even
longer. She felt that the building
ought to be renovated while the site
was still occupied.
This initial phase of the study
therefore enabled the Molenbeek
Housing Company as well as the
Municipal Council to adopt a position definitively in favour of renovation rather than demolition.
The second phase consisted of
using common sense to examine
what could be optimised in the
existing structure. The underlying
logic was that of improvement and
not compliance with standards.
This approach was not favoured
by the Brussels Region Housing
Company (SLRB), which had no
choice but to comply with standards - no exceptions. However,
Anne Lacaton didn’t give up: it
was first necessary to determine
how the existing structure could
be improved, otherwise any renovation operation would have been
pointless. Her firm also worked on
the human element: the teams visited the families in each apartment
in order to study situations of overcrowding or under-occupation.
This enabled them to discover, for
instance, that a bedroom intended
for one child was actually used for
three even though, in other apartments, certain rooms were unoccupied as the children had grown
up and no longer lived there. This
method showed that by simply
optimising the distribution of residents within the tower, via internal
movements, much could already
be achieved.
SOME FIGURES:
Footprint
381 m²
Total surface area
6482 m²
Number of apartments
97
Number of residents
242
Consumption
179 kWh/m²/year
Average heating cost
456 euros/year; 38 euros/month
Base rents
From 175 to 324 euros/month
Actual rents
122 to 227 euros/month
Fig. 6 to 12
The apartments are bright with a window in each room. The flat roof offers a
panoramic view over the city (© Lacaton & Vassal).
Significant technical considerations were also involved. The firm
proposed fireproofing and protecting the structure, making the
cores fireproof, adding sprinklers
to areas where fire resistance
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standards could not be met and
installing double door systems to
ensure the safety and evacuation of
people. The questions posed were
always extremely relevant. For
example, Anne Lacaton wondered
about the need to make a stairway
fireproof given that the compartments already were, and as the
stairways were split into two and
stairs are clearly not to be used
when a fire breaks out.
The conclusion from this second
phase was that it was necessary
to add one room per floor to maintain 97 apartments and satisfy
the needs of the residents even in
spite of the internal movements
of tenants and optimisations.
However, this work was never put
into practice as, simultaneously,
the Molenbeek Housing Company,
understandably not very enamoured with the idea of an occupied
renovation, decided not to rent out
the apartments that were being
vacated. The tower was therefore
progressively emptied of its population, but the firm continued
its work into finding ways to optimise the existing situation, believing that bringing the building into
compliance did not make sense
without this. As regards compliance with regional planning regulations, for example, following
these to the letter would mean
adding a small floor area to each
room. However, this type of extension can only be carried out if the
walls are destroyed, which is not
in keeping with the spirit of the
renovation, and only if the existing stairways are demolished and
replaced by other, fire service
compliant, versions.
Of course, Lacaton-Vassal’s approach
is all the more credible given that
they have already worked on other
towers in this way, most notably
the Bois-le-Prêtre tower in Paris
Energy
Biotopes
Water
Materials
Waste
ECOLOGY
Shared space
Diversity
History
Partnerships
Adaptability
Heritage
Resources
Quality
of life
Context
ECONOMY
SOCIAL
CULTURE
Density
Fig. 13
The four pillars of sustainable development.
which is almost the twin sister of
the Brunfaut tower. In 2000, the
firm undertook the renovation of
this building with the simple idea of
increasing the thickness of the walls
based on a bioclimatic winter garden concept. The principle involves
removing the existing façade and
replacing it with a double façade
(a double skin) with a three metre
space between the two sections.
This new space has to be managed
by each resident as a small winter garden. Inside, the work carried out was very understated and
extremely low tech, with a partition
being adjusted here and there. One
element that should be mentioned
is that no double flow technology
was used. The existing radiators
were retained but the boiler was
replaced. These minor renovations
enabled energy performance of
78 kWh/m²/year to be achieved.
This figure is far removed from the
low energy standard required for
the Brunfaut tower, i.e. 60 kWh/
m²/year, but hasn’t this gap been
largely offset by the savings made
in terms of special technologies
(including the embodied energy
used to manufacture, transport,
maintain and replace this technology)?
This study raises, in a somewhat
obvious manner, the question
of taking embodied energy into
account when evaluating the sustainable nature of a project. Today,
all possible on-board technical
means are used: since 2007, only
passive buildings with rainwater
harvesting systems for bathrooms
(systems which initially posed
severe problems when they were
combined with green roofs), thermal solar panels, photovoltaic
solar panels, double flow systems, etc. are built in Molenbeek-
Saint-Jean. The question of obsolescence also arises: we’re living
in an age where toasters are no
longer repaired! Let’s face it,
people no longer want to repair
things. It’s our culture. It’s not an
inevitability, of course, it’s simply
a way of boosting the economy and
creating growth, but look at what
is thrown out! Why not include
the costs of embodied energy in
the overall calculation of energy
balances and returns on investment? Where is the credibility in a
study that says a double flow system, after twenty years, pays for
itself if we’re following the toaster
model, i.e. if it’s been replaced
three times over the same period
of time? I am not saying that it
should not be done. We have a collective responsibility with regard
to global warming and therefore
have an obligation to research and
innovate. However, I think that the
issues of embodied energy and
obsolescence urgently need to be
considered and seriously included
in the calculations.
It is also important to consider
the question of balance between
the three pillars of sustainable
development and to include a
fourth: culture, as proposed by the
French urban planner, Philippe
Madec (among others). Culture
doesn’t belong to the social, the
economy or to ecology. There can
be no social project without culture. Culture is the basis of every
society. As part of this seminar, I
believe that considering this fourth
pillar as being completely inseparable from the three others would
help to address these issues of history, heritage and context that are
so important. I think that there is,
currently, an overemphasis on the
environmental pillar and, through
it, even more so on the energy pillar and the striving for energy performance (fig. 13).
Fig. 14 and 15
Sketches of the winning project in the competition
(© A229 architects/Dethier Architecture).
THE RESULT OF
THE COMPETITION
The architectural competition was
finally held with the inclusion in
the specifications - to the great
displeasure of Anne Lacaton - of
a requirement that the renovated
building comply with low energy
standards of 60 kWh/m²/year. The
Molenbeek Housing Company
received five proposals. To our
great surprise, all proposed passive projects! However, all of the
project authors confirmed to us
that without double flow ventilation it would not be possible to get
below the bar of 70 kWh/m²/year:
“If you require us to achieve 60,
double flow has to be installed. If
it is necessary to use a double flow
system, the additional cost involved
to achieve the passive standard is
negligible. We are therefore proposing a passive project to have
a greater chance of winning the
competition!”.
The five projects are therefore of
the passive type, most of them
based on increasing the thickness of the envelope, with the
obligation of adding extra space
in each apartment. The winner
(the Dethier Architectures-Atelier
229 firm) was announced after
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ONLINE
three days of deliberations by a
jury of 18 people, including Anne
Lacaton. The firm’s project stood
out from the others due to its close
adherence to the idea of heritage
identified in the study, including
the symbolic value of the building
which is part of the Brussels landscape (fig. 14 and 15). There was
something odd about calling for its
demolition while the Upside tower
was rising from the ground on the
other side of the canal. If high rise
buildings were the way to go then
either both or neither of the two
should be retained. In addition, the
project authors believed that to
increase space, five floors needed
to be added to preserve the proportions and elegance of the tower.
Their project was just as radical in
terms of the techniques to be used:
although all of the other projects
proposed very low ceiling heights,
due to cladding of the structures,
this project achieved a height of 2.6
m by proposing a system of solid
wood flooring (requiring major
work as well as negotiations with
the fire service), combined with the
use of visible engineering techniques to facilitate its replacement
where necessary. There will be
natural light in all of the hallways;
seating areas on each floor; distri-
bution of boilers and double flow
systems to save on stairwells.
CONCLUSION
I wanted to share three short quotations with you. The first is from
Anne Lacaton: “We have been too
fast with the standards and are
now paying the consequences:
it’s necessary to struggle to bring
about the sustainable!”. The second is from Pierre Blondel: “Are we
not in the process of over-complicating the simple fact of housing at
the cost of an excess of embodied
energy and, ultimately, consuming
ever more in order to supposedly
consume less?”. The third comes
from Lao-Tzu, so as to finish on a
positive note: “Failure is the foundation of success.” I believe that, in
this sense, we are definitely heading in the right direction.
NOTE
1. Druot, Fr., Lacaton, A., Vassal,
J.-Ph., PLUS - Les grands ensembles
de logements. Territoires d’exception.
Ed. G. Gili SL, Barcelona, 2007.
La tour Brunfaut. Présentation de
l’étude de définition des enjeux
d’une réhabilitation
De Brunfauttoren. Presentatie van
de studie over de definiëring van
de uitdagingen van een renovatie
La tour Brunfaut est un immeuble
emblématique du paysage
bruxellois. Édifiée en 1966, elle
incarne tout à la fois le rêve
moderne de la construction en
hauteur et l’ambition du logement
pour tous. Mais 40 ans plus tard,
la réalisation est jugée avec une
telle sévérité que son avenir
semble tout tracé : une lente
agonie suivie d’une démolition/
reconstruction, dans des gabarits
plus… acceptables.
C’est dans ce contexte que la
commune de Molenbeek-SaintJean décide en 2009 de mandater
l’agence d’architecture LacatonVassal, associée à Frédéric Druot,
afin de répondre à cette question
simple : doit-on vraiment détruire
la tour Brunfaut ?
Leur étude, à travers les notions de
patrimoine, d’identité, de confort...,
questionne les fondements mêmes
du concept de développement
durable, bien au-delà de la notion
de performance énergétique.
De Brunfauttoren is een
emblematisch gebouw in het
Brusselse landschap. De in 1966
opgetrokken toren belichaamt
tegelijk de moderne droom van
de hoogbouw en de ambitie van
een woning voor iedereen. Veertig
jaar later wordt de realisatie
echter met zoveel gestrengheid
beoordeeld dat haar toekomst al
helemaal lijkt vast te staan: een
langzaam verval gevolgd door een
afbraak/wederopbouw met meer...
aanvaardbare afmetingen. In die
context besliste de gemeente
Sint-Jans-Molenbeek in 2009 om
het architectenbureau LacatonVassal, in samenwerking met
Frédéric Druot, op te dragen
om een antwoord te geven op
deze eenvoudige vraag: moet
de Brunfauttoren echt worden
afgebroken? Aan de hand van
begrippen als erfgoed, identiteit,
comfort enz. stelt hun onderzoek
de grondslagen in vraag van het
concept duurzame ontwikkeling,
dat veel verder reikt dan het begrip
energieprestatie.
93
ONLINE
PRESENTATION AND RESULTS
OF THE “PLAGE” PROJECTS
LOCAL ACTION PLANS
FOR ENERGY MANAGEMENT
EMMANUEL HECQUET
CICEDD, NAMUR. HE HAS BEEN WORKING IN PARTNERSHIP WITH BRUSSELS
ENVIRONMENT ON THE IMPLEMENTATION OF THE “PLAGE” PROJECTS SINCE 2006
THE GOAL OF THE PLAGE PROJECTS IS TO IMPROVE ENERGY EFFICIENCY IN
BUILDINGS IN THE BRUSSELS REGION IN ORDER TO ACHIVE ENVIRONMENTAL
AND COST SAVING BENEFITS THROUGH THE IMPLEMENTATION OF PROACTIVE
ENERGY CONSUMPTION. SIGNIFICANT RESULTS HAVE BEEN ACHIEVED SINCE
THE LAUNCH OF PILOT TESTS IN 2006.
The regulatory background to the
programme of Local Action Plans
for Energy Management (PLAGE)
is the European Directive 2012/27
on Energy Efficiency and the
implementation of that directive
throughout the Region, imposing
a reduction of 30% in greenhouse
gas emissions by 2025 compared to
1990 levels.
OBJECTIVES AND METHODS
USED FOR THE PLAGE PROJECT
The goal of the PLAGE project is
to manage energy consumption
with a view to reducing it. It targets
managers or owners of large building stocks, as well as occupants,
encouraging them to take actions
that will produce rapid results. The
programme includes pilot tests and
will take place over three to four
years. The project primarily focuses
on rationalising energy use, application of regulations and insulation of
boiler installations than on making
heavy investments. We therefore
try to optimise consumption with a
priority on heating and (to a lesser
degree) on electricity. This programme applies to existing buildings, not to new buildings or buildings that have been the subject of
extensive renovation works.
We used a specific process quality
method or ISO, namely the Deming
Wheel (fig. 1). This is a continuous
improvement process. PLAGE
focuses first on energy accounting, or more precisely what we
call the “energy register”, as well
as an administrative and technical inventory of the building stock.
This first stage may be laborious
depending on the number of buildings. In the municipalities where
the PLAGE project was launched in
2006, the mere creation of a register
(involving up to 100 to 150 buildings)
took some time. The objective is to
identify “priority” buildings: those
94 | Presentation and results of the “plage” projects
that offer the greatest potential for
energy savings for the lowest cost.
This is followed by a three- to fouryear action plan involving the close
monitoring of energy consumption.
We analyse the initial results of this
energy accounting process, evaluate
them and then carry out corrective
measures where necessary. The
register and the action plan are then
updated and a new cycle begins. The
idea is to enter a virtuous circle for
improving the energy consumption
of the building stock.
The preparation of the action plans
allows us to draw up an outline of
the technical and energy aspects
of each building. The priorities are
always low-cost measures (e.g.
management of boiler installations,
rationalising energy use (RUE), and
generating awareness among the
occupants or training technical services). We then analyse the results
and energy consumption month
by month, year by year, to see if
the measures used are effective.
We use a series of reporting tools,
including the energy signature, that
allow us to compare monthly consumption with daily temperatures
and thus weather conditions.
THE ROLE OF THE ENERGY
MANAGERS
The key person in the PLAGE projects is the Energy Manager, who
works in an energy team within
the institution or company. One key
implement element in implementing the plan and the actions carried
out by the Energy Manger is concerted decision-making. It is essential that the Energy Manager does
not carry the whole energy burden
and responsibility for reducing consumption himself or herself, but
that everyone in the institution or
company is involved. The Energy
Manager is the conductor of operations. He or she coordinates
everyone who is involved - either
directly or indirectly - with energy.
He or she works with differently
composed teams depending on the
type of institution and the project
duration: these include technicians, buildings departments and/
or communication departments
of municipalities, players tasked
with generating awareness, etc.
In SISPs (public service real estate
companies) for example, he or she
works together with social assistants responsible for generating
awareness among occupants, and
also involves decision makers,
managers, etc. in the process. In
local councils this person will be the
alderman; in an SISP, the director.
The objective is to focus on transversal reports and to encourage
everyone involved to be aware of the
issues at stake. Subcontractors are
also involved; for example, maintenance companies are encouraged
to integrate the notion of energy
performance into their contracts.
There is also a requirement for exigency regarding maintenance contracts so that companies offer the
most effective services. At the end
of the programme carried out by
Brussels Environment, the participating communes have retained all
the Energy Managers.
MUNICIPAL AND VOLUNTARY
SISP PLAGE PROJECTS
The municipal and voluntary
PLAGE projects are interesting as
they show the results obtained for
buildings that have been identified
as a priority among large groups
of buildings (fig. 3). In these cases,
the Energy Manager started off by
targeting 10 - 12 priority buildings
among all the municipal buildings, and these then underwent
improvement plans for energy
efficiency. The resulting reduction
in consumption over the medium
term spilled over to the whole of
Fig. 1
PLAGE projects are based on the continuous
improvement process (© BE).
ENERGY
ACCOUNTING
ANALYSIS
OF RESULTS
2006
Municipalities 1
ACTION
PLAN
MONITORING OF
CONSUMPTION
2007
Hospitals
2008
Municipalities 2
VOLUNTARY PLAGE PROJECTS
Fig. 2
The origins of the PLAGE projects date back to 2005, and
are an initiative of Brussels Environment. The first pilot
experiments with the municipalities were carried out in
2006. In all, 15 of the 19 municipalities took part in the
experiment. The pilot projects were then rolled out in
hospitals and more recently with the SISPs. After ten years
of conclusive pilot tests, the programme will be made
mandatory for private sector groups of buildings of more
than 100,000m² and public sector groups of buildings of
more than 50,000m² (© BE).
2009
Schools
2011
SISP
2015
MANDATORY PLAGE PROJECTS
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the building stock as the practices
applied to the first buildings were
then applied to the others. Over
time, therefore, the energy performance of the whole group of buildings improved.
Voluntary PLAGE - PLAGE - MUNICIPALITIES
PARC
Specific consumption (kWh/m²)
These encouraging results were
also recorded in the SISPs that participated in the programme (fig. 4).
Voluntary Schools PLAGE
projects
The Schools PLAGE project started
up in 2009 and also produced
impressive results. This PLAGE
project was organised by a variety of
networks. The results show reductions in fuel consumption as high
as 22%, but electricity consumption
in certain instances continued to
increase. The reasons for this are
relatively simple: we see an annual
trend of a 2 - 3% increase over the
whole of the tertiary buildings sector, mainly due to the increase in the
amount of machinery used. PLAGE
projects focus primarily on reducing fuel consumption, and address
electricity consumption to a far
lesser degree. Working on a boiler
installation or optimising centralised hot water production are
campaigns that can be carried out
within a short space of time, while
electricity consumption is much
more widely dispersed throughout the building stock. Moreover,
reducing electricity consumption
requires changes in change consumer habits (e.g. photocopier
usage, computer usage, etc.) which
means that the effort required is
much more disparate. In addition,
in terms of cost, fuel consumption
is much more onerous than electricity consumption.
This article concludes by presenting two local schools where interventions took place. The first is the
Woluwé
Uccle
Jette
Koekelberg Etterbeek
PLAGE
Woluwé
Legends
year 1
Forest
Auderghem
Brussels
Specific consumption (kWh/m²)
Uccle
Jette
Koekelberg Etterbeek
Forest
Auderghem
Brussels
year 4
Fig. 3
It is interesting to note that situations within the municipalities were very different
at the start in 2008. We note that it is easier to make far-reaching improvements
with regard to energy to a group of buildings in very poor condition than to a group
of buildings that is already quite efficient (© BE).
municipal primary school, (preschool and primary school) in Forest
(fig. 5). The establishment currently
has 400 pupils with a heated surface
area of almost 5,000 m². It was built
in the 1930s and the energy efficiency is very low compared to the
number of pupils. The pre-PLAGE
energy cost per pupil/year was
206 euros. At the end of the programme, it was 142 euros per pupil/
year. Consumption dropped from 300
kWh/m²/year to 182 kWh/m²/year
thanks to classic PLAGE actions:
adapting the heating schedule to fit
in with occupancy of the buildings. We
tried to answer the following questions: Can heating start up later?
How low can we set the heating? Can
we lower the heating curves? Modify
the boilers? Some boilers ran at one
speed when they could run at two.
Voluntary PLAGE - SISP PLAGE
PLAGE sites : changes in average, normalised specific consumption
Legends
average 2009-2011 (kWh/m²)
average 2012 (kWh/m²)
average 2013 (kWh/m²)
Fig. 4
The SISPs involved currently in the PLAGE project account for almost 1,200,000 m² heated surface area. The priority for
intervention is placed on collective heating installations. Although this PLAGE project is not yet finalised – this is planned
during 2016 - we can already see major improvements of up to 20% reduction for the most advanced companies (© BE).
We corrected all of this. We insulated
the heating pipes, particularly in the
basement as it serves no purpose
to heat the boiler installation or the
corridors in the cellars. These are
low-cost actions that do not involve
façade insulation, replacing frames,
etc., which are not PLAGE actions.
Our actions involve working towards a
rationalised use with lower costs. The
result for this school was a reduction
of 42% consumption in heating over
four years which led to a 2% increase
in electricity, although this element
was not taken into account at all.
The financial savings was almost
27,000 euros.
The second example is the “Athénée
Robert Catteau” (fig. 6). Built in 1925,
this large school has a heated surface area of 14,000 m². It is a more
imposing site than that of Forest,
with a multitude of buildings, a big
centralised boiler installation and
underground pipes, which suggests
high energy loss in transporting
heat to each of the units. The situation at the beginning of the project
was worse than that of the previous
example, but the gains were nevertheless substantial after four years
as we dropped from 162 euros per
pupil/year to 135 euros and from a
consumption of 156 kWh/m²/year to
118 kWh/m²/year.
We changed the heating timetable.
This may seem like pure common
sense, but in reality it is not always
that easy. When the heating system
is centralised one has to ascertain
if there are separate circuits for
the different parts of the school
Fig. 5
Municipal primary school n° 9, rue du
Monténégro in Forest. At the start of the
PLAGE project, energy costs amounted
to 206 euros/pupil/year. At the end of the
project this had fallen to 142 euros/pupil/
year (A. de Ville de Goyet, 2015 © SPRB).
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(some buildings are used for music
classes or sports activities during
the evening or at weekends). It is
just common sense, however, that
the temperatures should be lowered considerably during school
holidays; however, in reality even
this is far from evident because the
cleaning team are present at times
and various activities take place in
the school holidays. Reorganising
everything may take time and may
present numerous obstacles for the
Energy Manager. These changes
cannot be carried out from one day
to the next. In this school we lowered the temperatures during the
night, replaced the outer doors,
regulated the thermostat valves
and trained occupants to use them
effectively.
In the end fuel consumption fell by
24%, but at the same time electricity consumption rose sharply
for the same reasons mentioned
above. We did not tackle this problem, and there is a lot of work for
the Energy Managers to take up
here. However, we noticed that
in spite of this increase, we still
achieved an energy saving of
22,000 euros over all the energy
vectors.
CONCLUSION
These examples show that the public
sector can set a strong example for
other sectors. The goal of Brussels
Environment is to encourage
demand and improve services via
a number of specific actions such
as training programmes, seminars
and pilot projects like PLAGE, in
order to improve energy efficiency
in the building stock. In view of the
results already obtained in previous
and current PLAGE projects, thanks
to an efficient methodology that
requires minimal financial input,
the programme has been made
mandatory for building stock in the
private sector with a surface area
of more than 100,000m² and more
than 50,000 m² in the public sector,
as part of the Brussels Air, Climate
and Energy Code (COBRACE).
This next compulsory action for
major blocks of building stock is
an important stage in reaching our
objectives to reducing consumption.
Translated from French
Fig. 6
Athénée Robert Catteau, rue
Ernest Allard in Brussels. Here again
considerable savings were made;
at the start of the PLAGE project
energy costs amounted to
162 euros/pupil/year and at the end
this had fallen to 135 euros/pupil/year
WEBSITE :
http://www.environnement.brussels/
thematiques/energie/economiservotre-energie/plan-local-dactionpour-la-gestion-energetique
Présentation et résultats
des projets PLAGE – plan
local d’actions pour la gestion
énergétique.
Presentatie en resultaten van
de PLAGE projecten: Plan voor
Lokale Actie voor het Gebruik
van Energie.
Depuis 2006, Bruxelles
Environnement a lancé plusieurs
appels à projets dans le cadre du
Plan local d’Action pour la Gestion
énergétique (PLAGE). Leur but est
d’améliorer l’efficacité énergétique
du parc de bâtiments de la Région
au bénéfice de l’environnement et
des finances des institutions en
instaurant une gestion proactive
des consommations d’énergie.
Des résultats importants ont été
engrangés, mettant en avant des
réductions de consommations
d’énergie de l’ordre de 15 à 20%
sans perte de confort sur une
période de trois quatre ans. Après
des programmes menés dans des
bâtiments scolaires, des hôpitaux
et divers bâtiments communaux,
un nouveau programme PLAGE
a été lancé dédié, cette fois, aux
logements sociaux étant donné
l’importance du logement dans
les consommations énergétiques.
La méthodologie et les résultats
de ces programmes sont
présentés, à travers des exemples
précis, à l’occasion de cette
journée.
Sinds 2006 lanceerde Leefmilieu
Brussel meerdere PLAGEprojectoproepen (Plan voor Actie
voor het Gebruik van Energie).
Het doel van deze oproepen is
de energie-efficiëntie van het
gebouwenpark van het Gewest
op te krikken ten voordele van
het leefmilieu en de financiën van
de instellingen door de invoering
van een proactief beheer van het
energieverbruik. In enkele jaren
tijd werden uitstekende resultaten
behaald, met verminderingen van
het energieverbruik van 15 tot 20%
zonder comfortverlies over een
periode van 3 à 4 jaar.
Na de projecten in schoolgebouwen, ziekenhuizen en
diverse gemeentelijke gebouwen
werd een nieuw PLAGEprogramma voor sociale woningen
gelanceerd, aangezien woningen
een aanzienlijk deel van het
energieverbruik voor hun rekening
nemen. Ter gelegenheid van deze
dag zullen de methodologie en de
resultaten van deze programma’s
worden voorgesteld aan de hand
van specifieke voorbeelden.
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THE BELGIAN BUILDING RESEARCH INSTITUTE:
A CONTRIBUTION TO HERITAGE MAINTENANCE
EXPLORING THE TRAINING OF HERITAGE
ADVISORS SPECIALISING IN ENERGY
MICHAEL DE BOUW AND SANDRINE HERINCKX
BELGIAN BUILDING RESEARCH INSTITUTE (BBRI)
IMPROVING THE ENERGY EFFICIENCY OF LISTED BUILDINGS IS A PRACTICE NOT YET
COMMONPLACE IN BELGIUM. NEVERTHELESS, OPTIMISING THE ENERGY EFFICIENCY
OF BUILT HERITAGE, WHETHER LISTED OR NOT, COMBINED WITH RENEWABLE
ENERGY, OPENS UP NUMEROUS OPPORTUNITIES.
THE BELGIAN BUILDING RESEARCH INSTITUTE (BBRI) IS SPONSORING A SEVEN-YEAR
PROJECT WHOSE PURPOSE IS TO GIVE PRACTICAL EFFECT TO THE “ARCHITECTURAL
HERITAGE ADVISORS SPECIALISING IN ENERGY” MEASURE INCLUDED IN THE NEW
CLIMATE PLAN DEVELOPED BY THE FLEMISH GOVERNMENT.
This article first presents the
Renovation Laboratory, which
is one of the laboratories of
the Belgian Building Research
Institute (BBRI), before addressing an energy training project for
heritage advisors that has recently
started in Flanders.
WHAT IS THE BBRI?
The BBRI works on new and existing buildings undergoing renovation, including heritage buildings.
It is a research centre for the construction sector.
It represents contractors in
Belgium and currently has 90,000
members. We provide scientific
and technical research and support and technical assistance
advice to our members and, more
generally, to professionals in the
construction sector. We also conduct more specific research, under
contract, for manufacturers, companies and public authorities. We
produce technical publications and
participate in scientific research
projects as well as specific development projects for companies.
We work towards the establishment of standards (through participation in standards committees),
and also support innovation, which
brings us outside the standards
context.
Our administrative offices are
located in Woluwe-Saint-Étienne
and our research centre, along with
all the laboratories, is in Limelette.
100 | The scientific and technical centre for construction renovation laboratory: a contribution to heritage maintenance
We also have a site in Brussels,
with a conference centre close to
the Gare du Midi/Zuidstation train
station. We will soon be moving to
a new a site close to Tour & Taxis,
in the canal zone. The Renovation
Laboratory, among others, will be
situated there.
THE MISSION OF THE
RENOVATION LABORATORY
This laboratory specialises in damp
problems in buildings and how to
treat them. It also deals with work
on building façades: cleaning, restoration, water-repellent protections, etc. It develops new activities relating to energy renovation
which, in the current climate, are
becoming essential.
Two presentations (pp. 76-83 and
pp. 86-93), relating to the housing
blocks are relevant to this article.
We are currently running a project that involves the collection of
all European experience regarding
energy renovation of façades carried out with pre-fabricated panels.
These panels have the advantage
of being usable while the buildings are occupied. Standardised,
they enable economies of scale
to be achieved. Adaptations are
of course possible, but the buildings involved in this project are
not listed. Nevertheless, this type
of solution could be envisaged
for garden cities or buildings that
are duplicated. Ultimately, we
are increasingly moving towards
energy efficiency, even in heritage buildings. The programme
presented below stems from this
observation.
THE TEAM
The BBRI has a reputation for
being particularly interested
in new buildings. However, the
Renovation Laboratory team is
made up of people who are trained
in heritage conservation. Two
of us have studied at the Centre
Raymond Lemaire. My colleague
Michael de Bouw completed a doctoral thesis on the “Model Schools
(1860-1920)” in Brussels. He is
also a member of the Vlaamse
Commissie Onroerend Erfgoed.
Samuel Dubois, who joined the
team recently, deals with energy
simulation. We therefore endeavour to have a team that enables all
aspects of heritage and energy to
be reconciled. We are also building partnerships: we give classes
in various institutes and universities; and cooperate with most of
the large universities and research
centres in Belgium (including
the Royal Institute for Cultural
Heritage), in Europe and further
afield.
ENERGY ADVISORS
SPECIALISING IN HERITAGE
OR HERITAGE ADVISORS
SPECIALISING IN ENERGY?
This project is aimed at training
energy advisors specialising in
heritage or heritage advisors specialising in energy. The principle is
that one individual should possess
both sets of these skills.
The current environment we are
working in is well known: the regulations are becoming more complex and restrictive and efforts
are increasing being expended
in trying to achieve the required
energy efficiency. In fact, the heritage value of buildings is often not
taken into account, a value that
cannot always be reconciled with
the primary motivation of achieving energy efficiency. However, it
should be noted that such buildings
generally make up only a tiny por-
tion of the stock to be renovated.
As a result, from the point of view
of overall energy efficiency and
savings in energy and greenhouse
gas emissions, it would be possible to not take them into account.
However, such an approach would
not be satisfactory. What is important is how these buildings are
used: if we do not intervene, they
will become too expensive to be
used, comfort standards will not
be satisfied and we run the risk of
having empty buildings which are
not maintained. It is principally for
this reason that we are trying to
reconcile the two aspects of heritage and energy.
Improving the energy efficiency of
listed buildings or high heritage
value buildings is not yet commonplace. There are several reasons
for this: on the one hand, the fact
that the Energy Performance of
Buildings (EPB) regulation does not
apply to such buildings and, on the
other, the difficulties encountered
in trying to reconcile the heritage
and energy efficiency agendas.
Finally, whether any unforeseen
negative consequences might
arise from such interventions is
as yet unknown. Nevertheless, the
EPB regulation may constitute an
opportunity. It is important for consideration to be given to it in order
to reduce greenhouse gases - even
if the biggest savings will not be
achieved on this type of construction - and, above all, to improve the
comfort and interior climatic conditions of such buildings.
One of the strengths of our project is its global approach to the
building. The heritage value is the
factor that will determine the limits of any intervention. It is inside
such buildings that we will attempt
to reduce energy consumption,
while endeavouring to minimise
the risks to the building itself. For
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this reason it is essential to work
not only on the envelope, but also
on the behaviour of the building’s
users. The objective is to maintain
a balance between the heritage
value and maximising energy efficiency, with a focus on the overall
balance of the building.
The relationship between thermal
efficiency, ventilation and damp is
a delicate one. It is necessary to
be aware of the possible consequences that may arise if one of
these aspects is affected in order
to avoid destabilising the operation
of the building. We are often called
upon to deal with issues occurring
on worksites after work has been
carried out where we diagnose
problems with damp connected
with the installation of new windows (double glazing) with frames
that are far more airtight than
those that were previously fitted.
The natural ventilation of the building is often found to be reduced
and problems with condensation and mould have appeared
(fig. 1 and 2). This is a classic
example. The balance of the building is affected and unforeseen
damage is caused. However, these
problems could have been avoided
with the use of a properly designed
ventilation system. Another classic example concerns cellars. If
one wants to make use of a cellar
or make it less damp, the initial
response is to increase the ventilation and heating. If the cellar in
question suffers from dampness
problems (perhaps less visibly so
initially) and the dampness is able
to migrate from the ground into
the stonework, it will evaporate
more quickly with the increase in
heating and ventilation. The salts
will then crystallise more rapidly
leading to damage to materials,
another unforeseen consequence.
These two examples illustrate the
importance of anticipating the possible consequences of any work.
With regard to maximising energy
savings, we prefer to use the
term “optimise” - it’s sort of like
Fig. 1
Efflorescence from salts and damage to materials in a
ventilated and heated cellar (© BBRI).
saying: “Well, we’re going to do
what we can, but always in accordance with the heritage values to
be conserved and the balance of
the building, which must remain
positive”. Where we want to satisfy
the requirements of the EPB or any
other regulation, we do everything
possible to do so. However, in this
programme, which is focused on
heritage buildings, we want to
approach things differently. We
start with the building, determine the limits of any action and,
through a series of minor or major
interventions, aim to reduce energy
consumption as much as possible
without attempting to achieve an
objective that is essentially theoretical. We adapt to the building
itself. We don’t want to reinvent
the wheel. We will of course use
innovative solutions where necessary, as there are materials that
have not yet been extensively used
or which are still on the expensive
side but which can be employed
when carrying out work on heritage buildings. In order to apply this
Fig. 2
Development of mould in a renovated vicarage, following
the installation of new frames and double glazing without
any system of ventilation (© BBRI).
approach to renovation, it is necessary to surround oneself with people who are familiar with historical
and heritage buildings.
The first phase of the programme
will be aimed at restoration architects who have previously worked
on heritage buildings and who wish
to improve their expertise in the
energy area. During the pilot years
we hope to be able to train around
fifty architects. Since the project
is being developed by the Flemish
Government it primarily concerns
architects active in Flanders, but
this experience will clearly be able
to be reproduced elsewhere.
PROJECT IMPLEMENTATION
AND TIMING
The project has just started. It
will be rolled out over a period of
seven years, from 2014 to 2021. It
is based on five pillars (fig. 3). The
first is an energy desk which we
will use to collect questions and
experiences concerning projects in
progress and which will help architects working on heritage buildings. The idea is to pool together all
information in a single database,
take advantage of both Belgian
and foreign experience feedback
and distribute this knowledge.
We have already begun to collect
data. The first project on which
my colleagues have started work
concerns the Klein Rusland social
housing development (in Zelzate).
Prior to carrying out the planned
works, surveys will be conducted.
We want to work on concrete projects in a multidisciplinary manner.
For this reason not only the will the
Renovation Laboratory be involved,
but so too will other BBRI laboratories. This is one of the strengths
of the approach, since we can call
on all the expertise of our various
teams. The energy desk will be
maintained beyond the seven year
period.
At the same time, during a two
year period, course modules will
be developed to train architects in
these energy and heritage aspects.
These courses will be given during
the third year. They should, in principle, result in some type of certification, the details of which have
still to be determined. We want to
take inspiration from both foreign
and Belgian examples to put all of
this in place. Representatives of
the sector will also be consulted.
A monitoring phase will then follow, carried out over four years.
We want to give a concrete dimension to the project which is why this
phase is the longest. At this stage,
while we already have information
on the possibilities for intervention, we have few data on experience feedback. In fact, information
has rarely been provided about
interventions carried out to date.
After the initial seven year period,
we will evaluate the training and
the possibility of integrating it into
existing training for restoration
architects.
In conclusion, I would like to call for
cooperation within the framework
of this programme. It is important
that the information is circulated
and that we are able to cooperate
with the sector. Working on energy
and heritage is fairly new. We are
increasingly engaging in such
thinking, but it is also necessary
for that thinking to be rooted, in
concrete terms, in practices. This
is why cooperation with all of the
professionals, in both the public
and private sector, is essential.
Fig. 3
Structure for the planned training of heritage advisors
specialising in energy (© BBRI).
A final point: if you are a contractor
and have practical questions about
a project, or any of the themes
addressed here, please don’t hesitate to contact us. We will respond
by telephone or e-mail and are
also willing to travel. In Brussels,
we have technical guidance and
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are able to extend our activities
to the entire construction sector.
Architects, consultancy firms, manufacturers, managers, etc. can contact us.
In October 2016, we will organise
an international conference on
the theme of energy and heritage.
We are still looking for partners. If
you are interested, please do get
in touch. Once again, it is a project
that we want to carry out in cooperation with the sector.
WEBSITES :
http://www.bbri.be
http://www.eechb.eu
La contribution du Laboratoire
Rénovation du CSTC à l’entretien
du patrimoine – Conseillers en
patrimoine spécialisés en énergie
De bijdrage van het
WTCB-labo Renovatie aan
erfgoedzorg – Gespecialiseerde
Erfgoedenergieconsulenten
Améliorer l’efficacité énergétique
des bâtiments classés : voilà une
pratique encore peu répandue
en Belgique. Les raisons sont
multiples. Citons en particulier
le fait que ces édifices peuvent
déroger à la législation belge sur
la performance énergétique des
bâtiments ou que les mesures
d’économie d’énergie sont souvent difficiles à concilier avec les
caractéristiques historiques des
bâtiments concernés. Pourtant,
l’optimisation énergétique du
patrimoine bâti, classé ou non,
alliée aux énergies renouvelables,
ouvre de nombreuses opportunités (réduction substantielle des
émissions de gaz à effet de serre,
utilisation et occupation plus
attrayantes des bâtiments grâce
à des factures plus basses et à un
meilleur confort...).
Cependant, il faut une approche
soigneusement réfléchie et cohérente pour réaliser ces objectifs
sans nuire au patrimoine, en
minimisant/éliminant les risques
pour les bâtiments.
Ces préoccupations sont à la
base d’un projet de sept ans
dont le but est de concrétiser la
mesure « Conseillers en patrimoine architectural spécialisés en
énergie » inscrite dans le nouveau
Plan climatique du gouvernement
flamand. Un des volets importants
du projet est une formation qui
s’adressera aux architectes-restaurateurs (expérimentés) qui
souhaitent améliorer leurs compétences en matière d’optimisation de l’efficacité énergétique du
patrimoine bâti.
La présentation se focalise sur la
conception du projet ainsi que sur
ses différentes étapes.
Beschermde gebouwen energieefficiënt maken is nog vrij
ongebruikelijk in België. Daar
zijn meerdere redenen voor,
zoals het feit dat de Belgische
energieprestatieregelgeving
voor deze gebouwen een
afwijkingsmogelijkheid voorziet
en het feit dat mogelijke
energiebesparingsmaatregelen
dikwijls moeilijk te verzoenen
zijn met de erfgoedwaarden
van het gebouw. Toch biedt
de energie-optimalisatie van
zowel beschermde als nietbeschermde erfgoedgebouwen
in combinatie met
hernieuwbare energie veel
mogelijkheden (beperking van
de broeikasgassenuitstoot van
een omvangrijk patrimonium,
aantrekkelijker gebruik en
bewoonbaarheid door lagere
facturen en een verbeterd
comfort, enz.). Om dit
echter te bereiken zonder
de erfgoedwaarden aan te
tasten en alle risico’s voor het
gebouw zelf te minimaliseren/
elimineren is een doordachte
en coherente aanpak nodig.
Deze bekommernissen liggen
aan de basis van het lopende
zevenjarenproject, dat de
concrete toepassing beoogt van
de maatregel ‘Gespecialiseerde
energieconsulenten voor
onroerend erfgoed’ van het
nieuwe Vlaamse Klimaatplan.
Één van de belangrijke
delen van het project is het
opleidingstraject ratiearchitecten
die hun vaardigheden inzake
de energie-efficiëntie van
erfgoedgebouwen verder wensen
uit te diepen.
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SUSTAINABLE RENOVATION
OF A BRUSSELS HOUSE:
A CHALLENGE FOR BUILDING TRADESMEN
JÉRÔME BERTRAND
CENTRE URBAIN ASBL
TRADITIONAL BRUSSELS HOUSES POSSESS NUMEROUS QUALITIES, IN TERMS OF
SUSTAINABILITY, THAT CAN BE ENHANCED DURING A RENOVATION PROJECT.
IN A CONTEXT WHERE THE MAJORITY OF WORKS ARE CARRIED OUT WITHOUT
THE INVOLVEMENT OF ANY ARCHITECT, THE TRAINING OF COMPANIES AND THE
EDUCATION OF CLIENTS PLAYS A DECISIVE ROLE.
This contribution starts by considering the advantages and constraints of the traditional Brussels
house (from the late 19th century
and early 20th century) in terms
of sustainability. This will therefore, initially, be a diagnostic type
approach. It will then address
energy renovation and heritage
through a number of examples
of works, focusing on a renovation carried out as part of the call
for Batex projects by Brussels
Environment (see p. 14), before
illustrating some of the difficulties
faced by craftspeople as a result
of the application of new requirements in terms of energy. It concludes with the issue of training
for these trades and the provision
of information intended for the
public.
THE BRUSSELS HOUSE:
A SUSTAINABLE RESOURCE
I really liked the suggestion by
Vincent Degrune to add a fourth
pillar to the three pillars that
define sustainable development
(the environmental, social and
economic aspects) to include the
cultural aspect (see p. 86-93).
It is with this in mind that I will
consider the heritage value of the
Brussels house. Figures 1 and 2
show two familiar Brussels urban
landscapes. Rue de Locht is lined
with neoclassical-inspired façades
rendered and painted in light tones.
They represent the first major phase
of urbanisation in the second half of
the 19th century. The second row, on
Rue des Pâquerettes, demonstrates
the emergence, at the end of the
106 | Sustainable renovation of a Brussels house: a challenge for building tradesmen
century, of a new taste for exposed
materials. The facings are composed
of bricks of various colours which
alternate with bands of blue or
white stones. During this period,
with the proliferation of balconies
and bow windows, façades were
increasingly coming alive in a threedimensional sense. Nevertheless,
what
characterised
Brussels’
urban landscape at the time was
the detail in the composition, which
is reminiscent of the works of early
Flemish painters. The detail was
the starting point from which the
whole was created (fig. 3 to 5).
From the perspective of energy
consumption,
the
contiguous
nature of traditional Brussels
houses is an asset since it reduces
the surfaces from which heat is
Fig. 1
Rue de Locht in Schaerbeek
(photo by author).
Fig. 2
Rue des Pâquerettes in Schaerbeek (photo by author).
Fig. 3, 4 and 5
Elements picked at random from different styles of façade.
Fig. 3: neoclassical moulding created in the render (photo by author);
Fig. 4: the stonework on a plinth. The way the light falls enables
the craftsman’s handiwork and the tool used - toothed chisel finish,
chiselling, etc. to be seen. (© G. De Keyser).
Fig. 5: lovely stained-glass window with a dragonfly pattern in an
Art Nouveau period intricately-shaped frame (photo by author).
fig. 5
fig. 3
fig. 4
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lost. However, there is significant
potential for energy improvements
in the rear façade, particularly
when it comes to the annexes,
as we saw in the presentation
by Julien Bigorgne from Apur
(see p. 24-34). Added to these
qualities is the comfort of these
old houses in summer, most
notably because of the difference
between the temperature in the
back yard and that in the street,
creating a cooling stack effect.
The flexibility of the design is also
an asset, as discussed in previous
contributions. This design, which
operates based on the “box”
principle, enables each room to be
turned into more or less airtight
compartments in the building,
heated in different ways depending
on the season. The entrance hall,
often sealed by an internal door
positioned at the top of the stairs
leading to the raised ground floor,
also serves as a buffer space in
terms of heat. There are other
mechanisms that also enable the
occupant to control comfort, such
as interior or exterior shutters.
While Venetian blinds have today
largely disappeared, they were
highly popular at the end of the
19th and beginning of the 20th
centuries. Old postcards show
that most of the buildings on the
city centre boulevards were fitted
with such blinds. Venetian blinds
filtered daylight, from which people
protected themselves to a greater
extent than today, and also helped
to combat summer overheating.
The majority of Brussels houses
at the time had rainwater cisterns
which could be used to supply wash
boilers, toilets, etc., by means of a
pump.
Another advantage of these old
buildings was the extremely long
Fig. 6
An owner with a love for heritage renovates his house. He removes, among other
things, a suspended ceiling installed in the entrance hall in the 1970s-1980s.
At the time, it was seen as essential to lower the height of ceilings in order to
“heat less air”. However, heating air requires little energy compared to heating
materials. Suspended ceilings like these which, moreover, are not airtight, are
useless from an energy perspective (© P. Brusten).
lifespan of the components from
which they were made, including second fix components such
as exterior joinery. The tendency
today is to systematically replace
old window frames in the name
of saving energy, even though
they are often in reasonably good
condition after a hundred years
or more of use. Yet the design of
this old exterior joinery enables
localised repairs to be carried
out, for instance replacing the
window sash bottom rail or a supporting member (lower window
sill). The blue stone slabs on the
balconies can also be repaired.
Traces of work are sometimes
visible: insertion of stone plugs
to fill a gap; metal staples which
are reminiscent of stitches to
strengthen a crack; etc. In an old
building, almost everything can, in
theory, be repaired. What defines
the know-how of the craftsperson
Fig. 7
The observation that the single-glazed
aluminium window frames of the
same era were not energy efficient
is identical. It was then considered
essential to ensure air tightness.
However, today, it turns out that these
frames are significantly worse from a
heat transmission point of view than
the single-glazed wooden frames that
they replaced. Now, these aluminium
window frames are, in turn, also being
replaced (photo by author).
is the unbroken continuity in the
craft between manufacture, the
construction of the component and
its repair. Within the context of the
diagnostic approach to Brussels
houses that should precede any
work on a building, it is interesting
to examine the energy renovation
campaigns carried out in the 1970s
and 1980s (fig. 6 and 7). Today,
exterior joinery installed thirty or
forty years ago is being replaced,
whereas if the maintenance cycles
had been continued the original
elements could have been preserved. The issue of construction
waste is also important as it makes
up a large part of the total volume
of waste generated in the Brussels
Region. Building tradesmen help
to limit the volume they produce by
mastering repair and maintenance
techniques that enable the existing
components in the building to be
maintained.
ENERGY RENOVATION
AND HERITAGE:
SOME EXAMPLES OF WORK
way of the original building materials remaining and generates huge
amounts of construction waste.
The example of the building
located on Rue du Rouleau (in
the Béguinage quarter, central
Brussels) is interesting as it was
the subject of a low energy renovation in the early 2000s (fig. 8 and
9). It was therefore, in defence of
the person behind the project, one
of the first energy renovations of
this type in the city. The interior of
the building was completely gutted leaving only the exterior walls
remaining. This is therefore an
example of façadism, justified by
the energy renovation. In effect,
the fact that only the exterior walls
were retained ensured the continuity of the interior insulation without
creating thermal bridges in front
of the floors. An operation of this
type does not leave much in the
The “menu” for a low energy renovation almost always includes two
interventions that have a potentially significant technical and aesthetic impact. The first concerns
the building envelope, which has
to be heavily thermally insulated
as well as airtight. The second
involves installing double-flow
ventilation with recovery of heat
in interior spaces that were not
designed for it. Figure 10 illustrates
a low energy project in which the
interior insulation of the façades
faces a very practical problem: the
join between the insulation and
the ceiling. In this case, solutions
must therefore be found in order
to reproduce the mouldings. The
same problem arises when integrating the double-flow ventilation.
Fig. 8 and 9
Low energy renovation, Rue du Rouleau, Brussels. Overview (left) and close-up of
interior wall insulation (right) (photos by author).
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fig. 10
fig. 11
Fig. 10 and 11
Close-up of interior wall insulation where it meets the
ceiling (left); perforated moulding concealing a ventilation
duct (right) (photos by author).
When a building is sub-divided, the
issue is more complicated than in
the case of a single-family dwelling. In effect, each apartment is
generally equipped with a separate
ventilation system. This system
takes up room as all the pipes have
to be placed somewhere. The solution devised for the project illustrated in figure 11 was to fit a very
large moulding, pierced by small
circular openings, in front of one
of the ventilation ducts in order to
integrate it visually into the ceiling
moulding.
We’ll now focus on the renovation
of a private home in Schaerbeek
(fig. 12). It is a neoclassical building,
of which there are thousands in
Brussels. This project is especially
interesting in that it succeeded in
reconciling an ambitious approach
to energy efficiency with a concern
for preserving the heritage value
of the building, even though
compromises had to be made
(such as replacing all of the window
frames). The low energy standard
(under 60 kWh/m²/year), was easily
achieved. By way of comparison,
the usual consumption of a building
of this type is somewhere around
150 kWh/m²/year. The energy
accounting religiously maintained
by the owners indicated, for the first
year of occupation, energy use of
42 kWh/m²/year for heating, which
is quite close to the consumption
calculated when the project was
being developed: 32 kWh/m²/year.
The rear façade was of no particular
architectural interest. It was
therefore insulated externally and
covered with new render. The blue
stone window sills, which acted as
thermal bridges, were replaced
by aluminium sills. Similar work
could not be envisaged for the
street-side façade for heritage and
urban planning reasons. Interior
insulation was therefore chosen,
even though this technique is more
difficult to implement as it often
has the result of enhancing the
thermal bridges (fig. 13). Contrary
to usual practice only the lower
part of the walls was insulated,
which avoided having to encroach
upon the ceiling mouldings with the
overlapping insulation. Although
only partial, this interior insulation
provides significant comfort as it
eliminates radiation of cold from
the wall surfaces closest to the
body. What’s more, there are a
sufficient number of non-insulated
surfaces remaining, avoiding the
concentration of any dampness in a
specific point on the wall. The risk
of spot condensation at the point
where the floors are anchored into
the façade is therefore reduced.
Another interesting aspect of the
project is the housing of the ducts
for the double-flow ventilation in
the old chimney flues (fig. 14).
This operation ties in with the
original function of chimneys
which also played a role in
building ventilation. They were
fig. 12
fig. 13
fig. 14
Fig. 12, 13 and 14
Rue Rubens 92 in Schaerbeek. This renovation project received an award as part of the
2008 call for Batex projects (photo by author). Notable work carried out included: partial
insulation of the street-side façade using wooden panels (fig. 13) and integration of the
double-flow system in the old chimney flues (fig. 14) (© A. de Nys and S. Filleul).
originally fi tted with individual
heating appliances and, with the
draw from the fire, some of the
rooms’ waste air was removed via
the chimneys. Another advantage
of installing the ventilation ducts
in the chimney flues: it turns out
that the system, according to the
occupants, is particularly quiet.
Fig. 15
Rue des Archives 28 in WatermaelBoitsfort. The project received
an award as part of the Brussels
Environment 2009 Batex competition
(© H. Nicodème and R. Tilman).
What is interesting about this
project is that it could be used
as inspiration for the renovation
of numerous Brussels houses of
the same type. However, it should
be pointed out that it was carried out thanks to the owners’
involvement and that they carried
out certain lengthy and difficult
works (such as fi tting the ventilation ducts in the chimneys) themselves. This work, which was in
keeping with the heritage value
of the property, would most likely
not have been financially possible if it had been carried out by a
company.
The renovation of a bel-étage house
in Watermael-Boitsfort (fig. 15)
illustrates a more radical operation
from an energy and architectural
point of view. Since the objective
was to achieve a passive standard
(under 15 kWh/m²/year), this project
required significant insulation of
the envelope and, in this particular
case, the street-facing façade was
insulated externally. Not generally
possible for urban planning and
heritage reasons, this technique
was accepted due to the presence
of the set-back area and because
it involved a building dating from
the 1950s-1960s which did not
present a significant heritage
issue. However, this approach does
raise questions: should this type of
operation be applied generally given
that, in certain cases, the interest of
the architecture of this period is yet
to be fully explored?
To conclude this chapter, let us go
back a little in time by examining a
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Fig. 16
Air vent incorporated into
the decoration of a sgraffito
(© M. Wal).
Fig. 17 and 18
Roofing poses various difficulties.
On the left, the join between the
roofing and cornice has been badly
executed. On the right, the cladding
has been installed correctly but a
mistake has been made at the level
of the zinc section intended to draw
rainwater into the cornice.
(photos by author).
fig. 17
fig. 18
Fig. 19
Correct installation of cladding but an
uncovered area remains between the
structure and the masonry behind the
chimney flues! (photo by author).
Fig. 20 and 21
Two examples of thermal insulation
of bow windows: installation of internal
doors fitted with low-emissivity glazing
(left) and lining of the apron in order to
install insulation (right)
(photos by author).
fig. 20
detail of the façade of the private
home of architect Henri Jacobs
at Avenue Maréchal Foch 9 in
Schaerbeek, dating from 1899. An
intriguing element can be made
out beneath the window sills on
the ground floor (fig. 16). It is a
lovely sgraffito that “clothes” part
of a technical installation: an air
vent, decorated with the monogram of the architect, connected
with the ventilation and heating
system. This image reminds us
that the introduction of technical
elements into traditional Brussels
houses is not a recent phenomenon. In his book, Les dimensions
de l’ordinaire, Vincent Heymans
presents the history of the traditional Brussels house from a
heritage point of view as well as
retracing the progressive introduction of technology. He shows
the reluctance with which each of
these technologies was greeted:
running water; gas; central heating; electricity; bathrooms; etc.
For example, in the 19th century,
taking a bath was seen as dangerous and required certain precautions to be taken... Every one
of these steps required modifications to buildings. The architect’s
role was, and remains today, to
give architectural form to these
new technologies which are not,
in themselves, problematic.
NEW CHALLENGES FOR
BUILDING TRADESMEN
The introduction of these new
technologies meant that craftsmen were confronted with previously unseen issues. Roofers,
for example, were faced with a
complete transformation of the
trade as a result of the changing
requirements in terms of thermal
insulation. In fact, the insulation
in a roof is composed of different
layers that it must be possible to
manipulate and manage. Interior
insulation of the existing roof
space (i.e. between the rafters),
which may be lined, does not pose
too many problems for a roofer,
as the technical details of the
actual roof itself are not modified.
However, in numerous cases – for
instance where there insufficient
under-roof height or existing finishes that need to be preserved it is not possible to apply interior
insulation. The solution proposed
fig. 21
in this case is roof sarking, which
consists of inserting the insulation
on top of the rafters, requiring the
roof to be raised. This technique
involves redesigning all the details
concerning water tightness and,
in particular, the join between the
roofing and the cornice gutter (fig.
17 to 19). Integration of thermal
or photovoltaic solar panels, insulated cladding, etc.; all of these
recent technologies are also a
challenge for the trade.
As regards exterior joinery,
extreme care is always required.
Should it be replaced? Should
the existing joinery be improved?
Various techniques enable the performance of exterior joinery to be
improved while preserving it. The
fitting of a double frame on the
inside is an efficient solution from
a thermal and acoustic point of
view. It is also possible to insulate
a bow window by installing internal
doors to create a buffer space. This
blocks cold in winter and prevents
overheating in summer. Thermally
insulating the apron is also a possibility (fig. 20 and 21). However,
all of this requires learning and
acquiring new skills since a joiner
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is not necessarily trained in thermal insulation techniques.
Double-glazing can often be fitted into an existing window frame
using a technique whereby the
glazing rebate is widened. The
width of the rebate, after milling,
determines the performance of the
glazing that will be fitted. In effect,
the U-value, or heat transmission
coefficient of the glass, is linked
to the thickness of the air or gas
space separating the two panes.
By way of example, to obtain a
U-value of 1.1 W/m².K, the thickness of the double-glazing interlayer should be 15 or 16 mm. Given
the cross-sectional profiles of old
wooden window frames, it is not
always possible to fit glass of such
thickness. Double-glazing with 12
mm or even 9 mm interlayers will
therefore often be chosen. Another
method is to fit single-glazing but
with a low emissivity layer. This
consists of laminated glass fitted
with a low emissivity layer that
reduces the heat transmission
coefficient of the single-glazing to
a U-value of around 3.2 W/m².K. As
a reminder, normal single-glazing has a U-value of 5.8 W/m².K.
This technique therefore offers
a substantial improvement even
if it is not comparable to the performance of contemporary double-glazing. In the case of heritage
buildings this type of glazing is
interesting, particularly when the
glass in sash window frames is
being replaced. This avoids having
to install double-glazing with fake
sash bars. This glazing is available
in drawn and blown glass versions
for the external face.
The thermal efficiency of front
doors can be enhanced by fitting
seals. In the case of doors adhesive
seals are generally used, while for
window frames the best solution is
fitting seals in a groove made using
a router. This is not recommended
for doors as the door frame could
be weakened. A brush seal can
also be fitted to the bottom of the
door to improve its performance.
An old door cannot, of course, be
brought up to level of performance
of a new one, but a significant
improvement can be made.
Craftspeople face limits in terms
of improving thermal efficiency
and I think that these limits should
be examined. A desire to ensure
the continued existence of trades
that enable existing elements to
be maintained and preserved risks
leading us into a dead end. Indeed,
it should be borne in mind that,
by dint of encouraging very high
levels of efficiency, a point will
be reached where the only choice
possible will be to replace, especially in terms of exterior joinery.
A quick examination of Batex projects shows, with some notable
exceptions, that almost every one
includes the replacement of window frames. Questions therefore
need to be asked about the level
that we want to achieve. As part of
the reflections underway on reorienting the system of renovation
and energy grants, it would perhaps be good to consider greater
progressivity in the thresholds. If
we take, for example, the fitting
of double-glazing in an existing
frame, the maximum U-value
required for the energy grant is
1.2 W/m².K (this requirement is
not appropriate for the renovation
grant). In a sizeable number of
cases, this level of efficiency will
not be achieved and individuals
could be discouraged. They will
therefore opt for the “easy solution” and replace everything. As
regards low emissivity single-glazing, it is automatically excluded
as it has a U-value of 3.2 W/m².K.
Double-glazing is subsidised for
the purpose of the energy grant
but is not eligible for a renovation
grant. Why not consider making it
eligible? In the case of wall insulation, grants also encourage high
levels of efficiency that rule out
the insulating renders applied for
the purpose of thermal correction
referred to by Julien Bigorgne from
Apur (see p. 24-34).
TRAINING PROFESSIONALS
AND EDUCATING INDIVIDUALS
For several years now, numerous
courses on the theme of sustainable renovation have been offered
to professionals by actors such as
Brussels Environment, the Belgian
Building Research Institute (BBRI)
and the Construction Reference
Centre (CDR). From these many
initiatives, I want to highlight
the “Interactive technical course
on window frames” organised
by the CDR and 21 Solutions.
This is a course that focuses on
both requirements in terms of
energy performance and constraints in terms of heritage. It
includes on-site visits, a diagnostic
approach and encourages a very
open-minded consideration of the
range of technical solutions available, according to the energy renovation scenarios chosen.
The role of the Centre Urbain’s
information desk, situated at
Halles Saint-Géry, is to inform
individuals about all aspects of
housing renovation. We don’t do
this work alone, of course. There
are also the associations that are
part of the Habitat network, as
well as other actors. We have been
around for 25 years and our special
feature is our cross-disciplinary
approach. We approach housing
from the perspective of different
themes - energy, building pathology,
heritage, acoustics, planning - by
establishing bridges between all
Fig. 22
Practical workshop organised by the Centre Urbain on the theme of exterior joinery maintenance (photo by author).
of these (sometimes contradictory)
constraints, around which private
individuals often find it difficult
to find their way. It should be
pointed out that a large portion
of renovation works, especially
those aimed at improving energy
efficiency, are carried out without
an architect. In addition to training
craftspeople, educating individuals
is therefore essential to enable
them to discuss things with their
contractors. The client can be
encouraged to hire an architect,
which we do regularly, but it is
still the case that a lot of works
are carried out without them. This
situation is problematic in the case
of energy-related works as such
renovations, which are carried
out in phases depending on the
resources available. However,
there is often no long-term view
taken of changes to the building.
The classic problem, referred
to earlier by Sandrine Herinckx
from the BBRI (see p. 102-106), is
replacing window frames without
considering the need for ventilation.
Such works do not necessarily
require planning permission and
the EPB regulation - which contains
obligations in terms of ventilation thus does not apply either. In this
way, such works often escape
any type of control. Education
and awareness-raising work is
therefore essential.
We also make available to private
individuals the Directory of Heritage
Trades which directs them towards
companies or craftspeople capable
of carrying out work with a view
to maintaining and repairing the
existing structure. We also organise
practical workshops for private
individuals (fig. 22). These focus on
maintenance techniques and, at the
same time, also describe works that
require the use of a professional.
They are run by craftspeople.
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BIBLIOGRAPHY
BERTRAND, J., Le Châssis de fenêtre
en bois - Concilier Patrimoine et confort,
Monuments and Sites Directorate of the
Brussels-Capital Region, Brussels, 2008.
BERTRAND, J., “Une maison bruxelloise
au banc d’essai”, in Les Nouvelles du
Patrimoine, Brussels, January, February,
March 2013, pp. 30-31.
HENNAUT, E., and DEMANET, M., Bois et
métal dans les façades à Bruxelles, King
Baudouin Foundation, Archives of Modern
Architecture, Brussels, 1997.
HEYMANS, V., Les dimensions de
l’ordinaire: La maison particulière à
Bruxelles, fin XIXe - début XXe siècle.
L’Harmattan, Paris, 1998.
SENNETT, R., Ce que sait la main. La
culture de l’artisanat, translated from
American English by P.-E. Dauzat, Albin
Michel, Paris, 2010.
WEBSITE :
Bâtiments exemplaires : http://www.
environnement.brussels/thematiques/
batiment/sinspirer-des-batiments-exemplaires/vous-cherchez-un-projet-batex
Bruxelles Environnement : Guide des
déchets de construction et de démolition, 3e édition (IBGE, 2009) http://
documentation.bruxellesenvironnement.
be/documents/Guide_Dechets_construction_FR.PDF
Bruxelles Environnement : Guide
pratique pour la construction et la
rénovation durables de petits bâtiments :
http://app.bruxellesenvironnement.be/
guide_batiment_durable
Centre urbain : www.curbain.be ;
www.patrimoine-metiers.be
Rénovation durable de la
maison bruxelloise : un défi
pour les artisans du bâtiment
Le bâti résidentiel bruxellois du
XIXe et du début du XXe siècle
constitue un patrimoine de
valeur tant par la cohérence des
ensembles urbains qu’il forme
que par la qualité exceptionnelle
du détail architectural.
Il est marqué par la présence
des métiers artisanaux qui
connaissent à cette époque
une véritable renaissance
malgré l’industrialisation.
Au-delà du renforcement de
la performance énergétique,
un projet de rénovation de la
maison bruxelloise aura pour
objectif de valoriser ses atouts
en terme de durabilité : flexibilité
et évolutivité du plan, usage de
matériaux traditionnels, principes
constructifs qui privilégient
l’entretien, la réparation, le
réemploi...
La majorité des rénovations de
logements sont réalisées sans
l’intervention d’un architecte ;
la qualité de ces travaux
repose donc avant tout sur la
sensibilisation et l’information
des maîtres d’ouvrage et sur
la formation des artisans du
bâtiment.
Direction des Monuments et des Sites
de la Région de Bruxelles-Capitale :
www.patrimoine.brussels
Duurzame renovatie van
de Brusselse woningen:
een uitdaging voor de
bouwambachten
Brusselse woningen uit de
19de eeuw en het begin van de
20ste eeuw vormen een waardevol
erfgoed, zowel wegens de
coherentie die ze verlenen aan
het straatbeeld als omwille van
de uitzonderlijke kwaliteit van de
individuele gevel. Dit heeft veel
te maken met de heropleving
van de bouwambachten in
die periode en dit ondanks de
industrialisatie. Bij de renovatie
van deze Brusselse woningen
zouden naast het verbeteren
van de energieprestaties hun
eigen troeven op het vlak
van duurzaamheid moeten
aangewend worden: flexibiliteit
en evolutiemogelijkheden van
het plan, gebruik van traditionele
materialen, bouwprincipes
afgestemd op onderhoud,
herstellingen, hergebruik...
De meeste woningrenovaties
worden uitgevoerd zonder de
tussenkomst van een architect;
de kwaliteit van deze werken
hangt dus in de eerste plaats
af van de sensibilisering en de
voorlichting van de bouwheren
en de opleiding van de
ambachtslui uit de bouwsector.
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CONCLUSION
The seminar was most instructive and clearly showed
the need, after a period of experimentation and innovation, to take time to evaluate and reflect with a view
to a possible reorientation of priorities, such as those
provided for in the Government agreement.
The issue of standards being applied to existing buildings was extensively covered. One key observation is
regarding the significant differences between the theoretical consumption resulting from models and the
actual consumption of buildings. This observation is
one we share with other European cities. It is therefore necessary to work on refining the models to take
greater account of the diversity of structures and their
environment on the one hand, and the methods of
occupation of buildings, apartments, etc. on the other.
This is an essential aspect of the sociology of buildings. Having a keen awareness of this data (with actual
consumption often being less than half the theoretical
results) will enable adjustments to be made to renovation works and the cost of investment. We must
aim for a balance between the results sought and the
resources required to achieve them in order to achieve
a satisfactory pay-back period.
The first step in this process is to implement monitoring of work on buildings in order to gather and evaluate
the data. It is important that we move away from our
somewhat entrenched opposing positions to be able to
discuss the issues at hand on a real, sufficiently documented and informed basis. Such monitoring should
include consumption before and after work and provide an opportunity to put in place a protocol for the
collection of data. Since this work is not starting from
scratch, this data collection must incorporate data
from audits already carried out. These data currently
remain in the records of public authorities who steer
the audits or in the hands of private companies who
carry them out, and even though they exist in large
quantities such data are not necessarily known or
compatible and therefore not capable of being compared. Pooling all of these elements in a common
118
database would facilitate access to them and enable
comparative analyses to be carried out.
The absolute priority is to generalise a base level of
renovation and insulation for the building stock. Initial
investments, as has already been shown in a number
of cases, are the most cost-effective, while those necessary to achieve the final KhWs to comply with the
normative requirements are the most costly. In short,
the key is to work on a greater number of buildings
with a view to regional economies of scale by intervening less intrusively on a systematic basis. The importance of a global approach is well established, both
at city and neighbourhood level as well as in terms of
preserving the urban planning and architectural qualities of old buildings. In this sense, we have arguably
already made progress, particularly insofar as protecting rear courtyards is concerned, which has been
a requirement since the introduction of the sectoral
plan in 1979.
The question of embodied energy was also raised in
the course of the seminar: the overall assessment
of any works must include embodied energy, i.e. the
energy consumed when implementing the techniques
and materials used in the renovations. Although this
question is difficult to address in practical terms, it
must not be ignored.
All of this speaks in favour of enhanced cooperation
between different institutional partners (foremost of
which are Brussels Environment and Brussels Urban
Development) and the construction sector, public or private actors in urban development, a range
of scientific partners such as the Belgian Building
Research Institute (BBRI) and the various universities
running programmes addressing these issues of
energy performance and modification of existing
buildings. Enhanced cooperation in the near future
between Brussels Environment and Brussels Urban
Development is included in the Government agreement, particularly with regard to the management of
mixed permits, environmental permits and planning
permission, simplification of the grants system with a
mechanism integrating renovation grants with energy
grants, and simplification of impact reports and
studies. These comprise an entire set of topics that
need to be re-evaluated to enable the Region to
respond to today’s key issues: population growth; the
need to provide sufficient quantities of housing; climate
issues; and reducing greenhouse gas emissions.
To conclude, thanks are due to the seminar’s organisers, especially the Monuments and Sites Department
who undertook this project. Thanks also to the speakers
for the quality and wealth of their contributions. This
one-day seminar represented an important step
towards the stated objective of reconciling energy performance and the preservation of not only exceptional
heritage but also common heritage, made up of the
old urban fabric.
Benoît Périlleux
Director-Head of Department
Brussels Urban Development
119
ON LINE
COLOPHON
General organisation
Anne-Sophie Walazyc
Authors
Jérôme Bertrand, Julien Bigorgne, Julien
Borderon, Vincent Degrune, Jonathan Fronhoffs,
Michael Govaert, Roald Hayen,
Emmanuel Hecquet, Sandrine Heirinckx,
Charlotte Nys, Guido Stegen, Manja Vanhaelen
Prefaces and conclusion
Benoît Périlleux, Arlette Verkruyssen,
Bety Waknine
Transcription of speeches
FADE IN sprl
English translation
Data Translations International
English editing
Cate Chapman - Skylark Editing
Graphics
The Crew Communication
The texts were transcribed from the verbal
presentations given by the speakers on
11 December 2014. The articles are published
under the responsibility of their authors.
All rights of reproduction, translation and
adaptation reserved.
Contact
Direction des Monuments et des Sites
CCN - Rue du Progrès/Vooruitgangsstraat 80,
1035 Brussels
www.patrimoine.brussels
Photo credits
While every effort has been made to identify all
copyright holders, any rights holders who could
not be contacted are invited to make themselves
known to the Monuments and Sites Directorate
of the Brussels-Capital Region.
Legal deposit
D/2015/6860/025. First edition.
Digital version
Newpress
Cover photo
Ch. Bastin & J. Evrard, 2008 © SPRB
Photo of Logis and Floréal in the contents
A. de Ville de Goyet © SPRB
Publisher / Verantwoordelijke uitgever
Arlette Verkruyssen, Director General of
Brussels Urban Development/Regional
Public Service of Brussels
CCN - Rue du Progrès/Vooruitgangsstraat 80,
1035 Brussels
The proceedings of the seminar are available
online in French and Dutch under the title:
“L’avenir énergétique du bâti bruxellois existant:
entre préservation et performance" and
“De energietoekomst van de Brusselse
gebouwen: tussen bewaren en presteren”.
120
121

a publication of brussels urban development 2015 online

Transcription

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