SMARTWIN

SMARTWIN
Polymer Network Liquid Crystal with
Reflective, Scattering and Clear States
Thematic Group 2
Lighting
FP4
Joule III
Project
Information
Contract:
JOE3-CT97-0068
Project Duration:
January 1998 to
December 2000
Project Partners:
Netherlands Organisation
for Applied Scientific
Research, NL
Centre National de la
Recherche Scientifique, FR
Polymage Sarl, FR
Centre Scientifique et
Technique du Batiment,
Services des Structures, FR
Innovative Sputtering
Technology NV, B
Bartenbach Lichtlabor
GmbH, A
Vidrios y Cristales Planos
Sole S.L., ES
URM 7643 – Laboratoire
Phisique de la Maatiere
Condensee, FR
Project Co-ordinator:
Agence de l’Environment
et de la Maitrise de
l’Energie (ADEME)
Direction du Batiment et
des Energies Renouvables
500 route des Lucioles
FR-06560 Valbonne,
France
Tel: +33.49-395 7921
Fax: +39.49-365 3196
Contact:
Marc Casamassima
Marc.casamammima@
ademe.fr
Research Directorate General
European Commission
Glazed component: increasing the sample size
Introduction
The SMARTWIN project has developed smart
window components consisting of glazed elements incorporating polymer network liquid
crystal (PNLC) films. Three main topics have
been investigated in detail:
• PNLC technology-based active films using
20mm x 20mm samples
• Glazed components of varying sizes from A4
(297mm x 210mm) to 800mm x 600mm.
• Evaluation of the smart window in terms of
their solar control performance and architectural requirements.
Project Objectives
• Enhanced, detailed knowledge of the characteristics of active films in terms of their selective
reflection of radiation in the 50nm and 150 nm
bandwidth under a range of test conditions.
• Knowledge of optimal conditions for the manufacture and assembly of glazed components
incorporating selective films.
• Detailed data on the thermo-optical characteristics of the glazed component and their
effects on daylighting and energy performance.
• Evaluation of energy performance characteristics and control strategies for a representative
range of conditions.
• A strategy for industrial manufacture of the
components
• Demonstration of prototype panels of up to
800 x 600 mm.
Project Results
The project has developed a prototype glazed
panel, in a range of sizes, on which an active film
is applied that can operate in three states: clear,
light scattering or diffusing and reflective. The
reflection bandwidth is in the range of 50 to 150
nanometres (nm) with the extent of reflection
adjustable by changing the applied voltage.
Response times are very short – measured in
microseconds. The mean value of the reflection
band is in the visible range or in the near infrared range of the spectrum.
Several methods have been devised and implemented in the prototype panels that allow significant broadening of the reflection band up to and
beyond 150 nm.
The physical and performance characteristics of
40 samples of film-coated glazing ranging in size
from 1 cm2 to 600 cm2 have been thoroughly
examined and documented.
Progressive increases in the surface areas of samples were achieved without any alteration in the
optical qualities occurring.
1.0
0.4
Transmittance
0.6
n/direct
0.8
0.2
W
av
800
700
600
ele
500
ng
th
(n
400
m)
300
0
20
40
80
60
Appl
i
100
ltag
ed vo
0.0
120
e (V)
Sample HG 17- Width: 70 nm-Mean wavelength 480nm Transmittance and reflectance as function of voltages and wavelengths
Small scale manufacturing procedures have
been tested in the laboratory and these have
enabled technical specifications and manufacturing criteria and strategies to be developed
for large scale industrial manufacture of the
glazing.
It has been determined that the maximum
modulation that is possible in the reflecting
state is 40% in the visible light range and 10%
in the solar range.
ufactured at laboratory scale, and testing of
small scale manufacturing procedures has led
to criteria and strategies that will assist in the
development of large scale manufacture plants
by industry.
Further industrial engineering is required prior
to large scale manufacture and there is scope
for improvements in the current broadband
reflection.
Market potential
Some market penetration has already been
achieved with a switchable internal wall (for
which the market is likely to be small) and with
a visual protection system and a switchable
sun protection glazing system for which the
market potential is expected to be substantial.
Contacts with potential manufacturers are
being pursued.
Comparison of the perfromance of an ideal
smart window with that of a real smart window with regard to energy performance and
the visual quality of daylighting provided in
occupied spaces has been undertaken. This has
enabled the definition of what improvements
should be made, in transmittance in the
reflecting state and in colour rendering, for
example.
The total energy savings achieved by the
SMARTWIN window under appropriate control ar of the order of 5%. However, the total
energy savings for an ideal, active SMARTWIN
window can range from 20% to 60% depending on the particular circumstances.
The feasibility of the technology has been successfully demonstrated using prototypes man-
Variation of the luminous and solar transmittance for a fixed width window and a translation of the window from 0.3 to 2.5 mm