Green Walls and Austin High-Rise Residential

Green Walls and Austin
High-Rise Residential:
A Strategy to Increase
Urban Vegetation
Randall B Maddox
Instructor
Werner Lang
csd
Center for Sustainable Development
UTSoA - Seminar in Sustainable Architecture
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UTSoA - Seminar in Sustainable Architecture
Green Walls and Austin
High-Rise Residential: A
Strategy to Increase Urban
Vegetation
Randall B Maddox
main picture of presentation
Fig. 1 Green wall on the Consorcio headquarters, Concepcion, Chile.
Downtown Austin: Past, Present,
and Future
According to a 2008 study conducted
by Capitol Market Research, Austin
was the fifth fastest growing city in
the nation in 2007, with a population increase of 4.3 percent. The
1.65-square-mile downtown area
(0.6 percent of total city land area)
was home to approximately 4000
residents in year 2000, and 5987
residents as of 2008 (Figure 2). At
that time there were 12 residential
projects under construction, seven
of which were condominium de-
velopments. The report noted the
surprising fact that “even after these
new apartments and condos are
completed and occupied, the population of downtown Austin will still be
less than it was in 1940,” when there
were approximately 12,500 people.1
In 2005, Mayor Will Wynn and
members of the Austin City Council established the goal of having
25,000 residents in downtown Austin
within 10 years.2 Furthermore, in
2007, Endeavor Real Estate announced its planned development of
a 28-story condominium/hotel as part
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UTSoA - Seminar in Sustainable Architecture
Fig. 2 Resident population of downtown Austin, past and projected.
of the Domain development.3 The
vision is for the Domain to become
a “second downtown,”4 with 50 new
buildings ranging in height from two
to 26 stories.5
UHIE, Plants, and Green Wall
Technology
Clearly Austin’s future includes dramatic and intentional densification,
especially in its downtown core. If
this development is going to be done
sustainably, then UHI factors must
be taken into account in building
design. “Among all cooling measures, urban vegetation is the most
effective way to directly cool UHI, by
providing shade and, indirectly, by
plant evapotranspiration.”6 One very
familiar way to do this is through the
construction of green roofs. However, in high-rise buildings such as
the condominium and apartment towers recently built in Austin, the roof
represents a very small percentage
of the building skin area. Another
potential lies in the green wall, and it
is this strategy we investigate in this
section.
The effects of plants on UHIE are
complex and interrelated. Two
important actions that plants perform
are the absorption of gaseous pollutants (including carbon dioxide) into
their internal tissues, and the filtering out of airborne particles as air
passes over leaves and stems and
the particles settle onto their surfaces. These particles are then washed
off by rain.
4
What plants do
For our purposes here, we are more
concerned with a plant’s potential
for shading and evapotranspiration
(ETP), and the effects these have
on UHIE and energy usage. Huang
concluded from DOE-2.1C models
of shading and ETP that increasing
the current level of urban tree cover
by 25% can save 40% of the annual
cooling energy use of an average
house in Sacramento, and 25%
in Sacramento and Lake Charles.
Furthermore, by placing these trees
to optimize shading benefits, the
values jump to 50% for Sacramento
and 33% for the other cities.7 Givoni
reports that on hot sunny late afternoon days in Miami, “the average
temperature of walls shaded by trees
or by a combination of trees and
shrubs was reduced by 13.5–15.5
deg-C. Climbing vines reduced the
surface temperatures by 10–12 degC.” He also refers to a study on a
double-width mobile home where the
introduction of landscaping reduced
a summer day’s air conditioning
needs from an average of 5.56 kW to
2.28 kW. During peak load periods,
the drop was more dramatic: 8.65 to
3.67 kW.8
The shading benefit of vegetation
is more complex than merely blocking solar radiation from a building
façade. “Vegetative surfaces reduce
long-wave heat gain to the house
because their surface temperatures
are low compared to hard surfaces
such as sidewalks, asphalt, or bare
ground.”9 Thus vegetation is more
effective as a shading device than
an inanimate object, much of whose
heat would be dissipated simply by
re-radiation.
Concerning evapotranspiration,
plants “reduce conductive and
convective heat gain by lowering dry-bulb temperatures through
ETP.”10 Huang notes that, “from the
point of view of energy conservation, a tree can be regarded as a
natural ‘evaporative cooler’ using up
to 100 gallons [379 L] of water each
day. This rate of ETP translates into
a cooling potential of 230,000 kcal
[267.4kWh] per day. This cooling
effect is the primary cause for the 5
deg-C differences in peak noontime
Green Walls and High-Rise Residentiall: A Strategy to Increase Urban Vegetation
temperatures observed between forests and open terrain.”11 The beauty
of this fact is revealed in studies that
showed consistently over a 15-year
period that ETP rates are more
closely related to net solar radiation
than to air temperature or relative humidity.12 Thus in a hot, humid climate
like Austin, where manmade evaporative coolers are an ineffective
technology, plants are still capable
of lowering dry bulb temperatures
through ETP, even in the presence of
high moisture content.
It is helpful to note that these studies reporting decreased demand for
cooling are due both to the effects
of shading and ETP. In particular,
Huang notes that shading accounts
for only 6–17% of the total savings in
some of the studies, and for 10–35%
in the other, shading studies. The
remaining savings result from the
lowered temperatures due to ETP.13
Green wall technology
One well known way to incorporate
plants into building design is through
a green roof. Another option is the
green wall, where plants are integrated into the building façade. The
technology of green façades is much
newer and less well known than that
for green roofs.14
Most of the research being done to
advance green façade technology
centers around two types of green
walls. The first strategy uses climbers—plants that are rooted in the
ground or in pots and encouraged
to grow up a structure exterior to the
building (Figure 3). To encourage
the growth of climbers is hardly new
technology, for ivy has been used as
an exterior wall covering for centu-
Fig. 3 Climbers on a green wall of the Swiss Re building, Munich, by Officium Design Engineering.
ries. However, more technologically
advanced practices will most likely
involve holding the climber plants
away from the building façade. This
research was pioneered primarily in
the German speaking countries.15
The second technology is commonly called a living wall, where
plants grow in containers attached
to structural elements at the exterior
wall (Figures 1 and 4). These plants
may either be rooted in soil or grown
hydroponically—that is, fed by nutrient solutions instead of being rooted
in soil.16
Of course, a green façade need not
be a complex or advanced technical
design achievement in order to warrant consideration. Indeed, in what
follows, we will present thumbnail
calculations on a hypothetical Austin
high-rise residential tower, where
we presume nothing more than
integrated planter boxes containing native Texas shrubs circling the
entire building façade on every floor.
Conceptually this is no more complex than imagining that residents
merely grow shrubs in planter boxes
on their balconies. Our goal is not to
discuss the design of a green wall so
much as to speculate about its value
in addressing UHIE.
What green walls do
As a general principle of urban landscaping, “the effect of open areas of
vegetation is generally reduced if the
area lies lower than the land around
it or if it is surrounded by walls or peripheral vegetation—in these cases
the barriers prevent cool air draining
from the site to influence adjacent
areas.”17 This is an argument for
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UTSoA - Seminar in Sustainable Architecture
the use of vegetation on a vertical
surface, for “solar energy heating the
side of a building will generate more
powerful convection currents than
it will on a horizontal surface, which
climbers—through their cooling
effect and the creation of complex
air flows—can minimize.”18 Consequently, the impact of green walls
on urban heat islands is significantly
more complex than that of mere
shade trees, for the intent is to maximize the shading effect and to exploit
micro-climate changes created by
ETP very close to the building skin.
Furthermore, green walls also act
as a layer of insulation, for they slow
wind and can reduce conductive and
infiltration heat gains.19
The value of these apparent benefits
is hardly clear cut, however. In 1988,
Hoyano conducted experiments with
a vine sunscreen shielding a southwestern facing veranda. Dishcloth
gourd, a vertical vine, was installed
in front of the veranda, and its effects were compared to a similar
unscreened veranda. The screen
was effective as a shading device,
significantly reducing insolation
inside the veranda; however, the leaf
temperature of the vine was higher
than the ambient air. The air temperature inside the screened veranda
was higher than the ambient air,
but still lower than the air inside the
unscreened veranda. Hoyano’s conclusion is that the overall effect of a
such a screen in a hot, humid climate
might be negative, in that airflow
through the contained space can be
significantly restricted. However, he
reports that the surface temperature
of the exposed walls averaged 10
deg-C above the ambient air without
the vine cover, while with the vine
cover, it averaged 1 deg-C below it.20
6
Fig. 4 Modular living wall system by Elevated Landscape Technologies, Brantford, ON.
Finally, in studies prior to 1991, it
was not clear whether the interactions between the shading and
insulation effects of a green wall
were necessarily productive. In
particular, it had “been demonstrated
that the average external surface
temperature of white walls, even in
a very sunny climate, is lower by
about 2 deg-C than the average
ambient air temperature.... In such
a case shading the wall by plants,
which may also reduce its long-wave
heat loss, may be counter productive.”21 However, we must note that
the white wall is a local effect, which
merely reflects the heat from the
building, possibly onto another building façade, and still contributes to the
overall UHIE. Givoni notes that “this
interaction between the shading and
the insulation effects has not been
studied at all in previous investigations.”22 The 1991 date of this com-
ment suggests further investigation
into the more recent literature.
Austin wall temperature data
To gain a sense of the effect on
temperature that shading and plant
coverage can have on exterior
walls, several sites in Austin were
tested using a Raytek MX4 infrared
thermometer. The study included
eighteen segments of exterior walls
in downtown Austin, each of which
was tested twice on the same sunny
August day. Every tested wall segment contained two spots in close
proximity, one exposed and another
covered with vine growth. Materials included limestone, light colored
stucco, brick (painted or unpainted),
and concrete.
Depending on the time of day, the
Green Walls and High-Rise Residentiall: A Strategy to Increase Urban Vegetation
Fig. 5 Statistics on ivy-covered walls in downtown Austin.
orientation of the façade, and the
possible presence of an overhead
awning or eave, exposed surfaces
might or might not have been receiving direct solar radiation at the
moment of testing. Figure 5 contains
basic statistics derived from the
collected data. To illustrate, of all
wall surfaces where a fully exposed,
insolated section lay in proximity to
a section overgrown with vegetation,
the average temperature difference
between these two test points was
9.45 deg-C.
The process of data collection and
analysis in this study revealed several difficulties in drawing any meaningful conclusions from the results.
First, exposed surfaces that were not
receiving direct solar radiation at the
time of testing could vary widely in
temperature, based on the amount of
indirect radiation they were receiving or perhaps whether they had
received direct radiation earlier in
the day. A second caveat applies to
awning or eave shaded surfaces, for
these shading devices were above
the wall segment and did not shield
it from indirect solar radiation or reradiation from nearby surfaces.
These results do suggest, however,
that plant covering is of value in
reducing temperature, if for no other
reason than that it shades completely and consistently throughout
the entire day. Measurement of any
meaningful refinements of the effects
of plant coverings would clearly
require much more controlled experiments than the one conducted here.
Fig. 6 Roof-to-cistern rainwater transfer system, Institute of
Physics, Berlin.
Case Studies
We now consider two case studies of
green walls. The first is the Institute
of Physics in Berlin-Adlershof, a project by Augustin and Frank completed
in 2003. The second is a purely
hypothetical case study, where we
investigate the feasibility of a highrise residential tower in Austin that
includes a façade greening strategy.
Fig. 7 Part of the cistern system, Institute of Physics, Berlin.
Case study 1: Institute of Physics
The Institute of Physics houses
offices and research for Humboldt
University of Berlin. It incorporates a
variety of sustainable technologies,
including rainwater collection and
management, green roof and façades, and adiabatic cooling with the
help of collected rainwater (Figures
6–10). The facility has no connection to any rainwater sewer, but
collects and stores rainwater in five
cisterns located in two courtyards.23
Fig. 8 Wisteria climbers, Institute of Physics, Berlin.
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Fig. 10 Adiabatic cooling unit, Institute of Physics, Berlin.
Fig. 9 Planters on the façade, Institute of Physics, Berlin.
The design process included extensive modeling of these systems in
order to maximize their expected efficacies. For the green walls, Wisteria
sinensis proved to be the best choice
as a climber that can grow from a
planter under extreme conditions.
Also, because wisteria is deciduous,
winter sunlight penetrates directly
into the interior. The explicit goals of
the Institute’s green walls were precisely those mentioned previously:
1) to climatize the building passively
Fig. 11 Devices for measuring potential evaporation of
wisteria, Institute of Physics, Berlin.
through summer shading and winter
insolation, and 2) to harness ETP to
improve the microclimate inside and
around the building.24
Preliminary calculations for potential
evapotranspiration rates (PET) were
compared to actual ETP rates by
monitoring the plants’ water usage
(Figure 11). Once the plants had
grown to adequate size, Schmidt
notes that, “compared to the PET
the real ETP is extremely high.”25
Fig. 12 Green wall on the Consorcio headquarters, Concepcion, Chile.
8
(See Figure 12.) He reports: “In the
summer months July until September
the water consumption for the quite
well developed Wisteria sinensis
increased up to 420 liters per day for
56 planter boxes. This represents
a cooling value of 280 kWh per
day. The mean evapotranspiration
between July and August 2005 for
the south face of the building was
between 5.4 and 11.3 millimeters per
day, depending on which floor of the
building the planters were located.
Green Walls and High-Rise Residentiall: A Strategy to Increase Urban Vegetation
45000
40000
Total radiation (kWh/m^2)
35000
30000
north wall
25000
south wall
west wall
east wall
20000
15000
10000
5000
0
1
2
3
4
5
6
7
Month
8
9
10
11
12
Fig. 13 Total monthly insolation (kWh/m2) on façades of a building in Austin.
This rate of evapotranspiration represents a mean cooling value of 157
kWh per day.”26
According to the National Renewable
Energy Laboratory, an average June
day in Austin provides a solar radiation potential of 5.5–6.0 kWh for a
1m2 photo-voltaic panel.27 Assuming
a panel operates at 15 percent efficiency, a 1m2 panel can generate approximately 0.863 kWh of energy on
an average June day. Thus it would
require approximately 325 m2 of PV
panel to produce the equivalent 280
kWh of cooling value provided by the
wisteria.
Case Study 2: A hypothetical highrise residential tower in Austin
The express goal of this study of
green walls is to make a case for
the effectiveness, feasibility, and
desirability of incorporating a green
façade into a high-rise residential
tower in Austin. In what follows, we
do not argue for either climbers or
living wall technology, but instead
assume that plants could, for example, simply be rooted in planter
boxes along the building’s façade.
Furthermore, given the number of
variables relevant to a green wall’s
performance and the complex interactions between them, it would be
impossible to argue for any concrete
energy savings or quantifiable impact
on UHIE. Any such local impact on
the UHI is beyond the scope of this
investigation. Instead, we choose
to describe a specific design strategy and convey the magnitude of its
impact solely by comparing it to the
presence of trees in the downtown
Austin landscape. Thus we may
develop a sense for a green wall’s
impact on the entire urban system.
Considerations
A first consideration in the design of
a green wall is the NSEW orienta-
tions of the building’s façades and
the insolation available to each.
Figure 13 illustrates the results of an
Ecotect model by Stefan Bader (University of Texas School of Architecture) addressing this question for an
Austin setting. Values in the graph
are total insolation values (direct and
diffuse) on a one-square-meter area
for an entire month (kWh/m2).
For the month of December, no direct sunlight falls on the north façade
of a building in Austin. Thus the
7844 kWh/m2 in Bader’s simulation is
due solely to diffuse solar energy in
the atmosphere. Naturally, the south
façade receives the most solar radiation in winter. Note that a somewhat
counterintuitive phenomenon occurs
during summer. Due to the northerly position of the June sun in early
morning and late evening, as well as
its very high altitude in midday, the
north façade of a building receives
more solar radiation than the south.
However, both of these amounts are
dramatically less than the radiation incident on the east and west
façades.
A second consideration in green wall
design is plant choices. Dunnett and
Kingsbury note a trend in green roofs
to use only locally native species.
This rather obvious criterion makes
sense, not only for reasons concerning plant growth, but as a statement of how the building’s design
is integrated into the culture of the
area. They also claim that plants
for a green roof should be drought
tolerant. This makes sense as well
for Austin, but is likely not necessary
in the green wall design we will describe. Two hardy plants for possible
use on a green façade are plumbago
and lantana.
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UTSoA - Seminar in Sustainable Architecture
Fig. 14 Plumbago auriculata.
Fig. 15 Lantana camara.
Plumbago (plumbago auriculata)
thrives well in Austin and produces
light blue flowers through most of the
year. It will climb to almost 20 feet,
but only by tying it onto supports, as
it has no real climbing mechanism
of its own.28 Figure 14 illustrates
the natural shape of plumbago, so
it might be ideally suited to a typical planter box on the balcony of a
residential tower.
produces flowers of widely varied
colors (Figures 15 and 16). Depending on the strain, a lantana will
either grow upward into a bush, or
trail outward along the ground. This
latter form could be used to cascade
down a façade to shade it. Lantana
is extremely hardy and drought
tolerant, and tends to attract hummingbirds and butterflies. It likes as
much direct sun as possible, and
would therefore be a good choice for
façade greening on all but a north
face.
Lantana (lantana camara or lantana
montevidensis) is also a popular
plant native to central Texas, which
Fig. 17 The 360 condominiums, Austin.
10
Fig. 18 Rendering of the Monarch condominiums, Austin.
Fig. 16 Close-up of one type of bud on lantana camara.
Fig. 19 Rendering of the Austonian condominiums, Austin.
Green Walls and High-Rise Residentiall: A Strategy to Increase Urban Vegetation
A third consideration in green wall
design is how the plants will be
watered. Even in a climate much
wetter than Austin, it is not reasonable to think that rainwater collected
from the roof of a high-rise building
is adequate for green walls, for the
façade surface area can easily be
twenty times that of the roof.29 For a
residential tower, however, there is a
potential alternative in the gray water
generated by residents, described in
what follows.
Designing a tower in Austin
Of the residential towers recently
built in downtown Austin, three
have very similar exterior shapes in
sizes—the 360, the Monarch, and
the Austonian (Figures 17–19) Using one of these as a template, say
the Austonian, let us imagine that
the entire perimeter of a single floor
is surrounded by balconies that are
bounded by planter boxes for native
shrubs. One such design is illustrated in Figure 20. Assume that the
soil container is 0.5 meters (19.8 in)
wide. We address a strategy for providing adequate water for the plants.
Since the context of this study is
a residential tower, we know that
residents will generate significant
gray water through such activities
as showering. A typical American
shower dispenses approximately 2
gal/min (7.6 L/min), which means
that a shower of around five minutes
duration will require, say, 40L (10.6
gal) of water. This volume is precisely the amount needed to provide
1cm depth of water into a 0.5m wide
planter that runs a length of 8m. In
other words, if we assume that every
8 meters of façade along one floor
of the building corresponds to one
5-minute shower every day, then this
Fig. 20 Concept of façade greening for an Austin high-rise condominium.
alone will water all the plants on the
building skin with 1cm of water every
day.
Impact of shrubs on microclimate
Initial motivations for this study were
an understanding of how the presence of green façades on an Austin
building can impact UHIE, and the
development of some thumbnail
quantification of the role that native
shrubs might play. These hopes
were originally a response to a statement in Santamouris: “Moffat and
Schiller (1981) report that an average tree evaporates 1460kg of water
during a sunny summer day, which
consumes about 860 megajoules
(MJ) of energy, a cooling effect
outside a home ‘equal to five average air conditioners’.”30 Many have
conducted research that includes assumptions about an “average tree,”
so it seems only reasonable that one
might use this notion as a unit of
measure with which to understand a
variety of plant types.
If anything has become clear in the
pursuit of this goal, it is that this sort
of question is an extremely murky
one due to all the relevant design
variables, complex interrelationships
between the quantities we want to
measure, the potentially disparate
behaviors of different plants, and the
range of possible plant performances
resulting from the amount of water
that a plant receives.
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Yet, even with all these complicating
factors, the one question still remains: Given that much research on
ETP has been conducted using the
notion of an “average tree,” can we
infer what an average tree actually
is, and then approximate a conversion factor from an “average tree” to
an “average shrub,” thereby giving
us at least some sense of the impact
of greening the façades of a high-rise
residential tower? This is the final
question for this section, and we address it in terms of total leaf area of
trees and shrubs.
First, Huang assumed in his DOE2.1C modeling that a “mature tree
has a top view projection area of
50m2,” which appears reasonable
and consistent with other assumptions in the literature.31 Second, in
order to relate total leaf area of a tree
to that of a shrub, we need a sense
of a plant’s leaf area index (LAI),
which is the ratio of the total leaf
area of a plant to its canopy area,
that is, its top projection view.
The literature on LAI is extensive.
Lalic and Mihailovic noted a range of
tree LAIs between 2 and 18.32 However, in Sonnentag et al extensive
field measurements yielded average
LAI values of 1.59 for trees and 1.57
for shrubs in their study.33 If these
numbers are a basis for any relationship between trees and shrubs, it
implies that an “average tree” and
an “average shrub” with the same
canopy area will likely have comparable total leaf areas.
Assuming this, we may then convert
our residential green wall shrubs
into a tree equivalent in the following way. If a planter box along the
façade holds a mature shrub whose
spread is 1 meter wide, then a 50-
12
meter length of planter holds the
rough equivalent leaf area of one
average tree. Rough measurements
from Google models of the Austonian reveal that the perimeter of the
residential floors is approximately
133 meters. Thus by wrapping one
floor of the Austonian in a green wall
of this sort, we have introduced the
equivalent of 2.67 trees into downtown Austin. With 44 residential
floors in the building, we have the
equivalent of approximately 117.5
average trees on the façade of the
Austonian. Using Santamouris’
claim that an average tree evaporates 1460 kg of water per day, this
requires approximately 917 kWh of
energy. In terms of PV panel area,
1063m2 would be required to generate this amount of energy on an
average June day in Austin.
they also stand to have a dramatic
impact on the infrastructure required
for downtown Austin to support such
a large number of residents.
Notes
1. Heimsath, Charles, President of Capitol
Market Research, report to Downtown Austin
Alliance, April 2, 2008, p 5.
2. Boyt, Jeb, letter to Mayor Will Wynn and
Austin City Council members, August 3, 2006.
3. Austin Chamber of Commerce newsletter,
February 2008, p 5.
4. Renovitch, James. “Recreating the Domain,” Austin Chronicle, May 8, 2009.
5. Novak, Shonda. “Condo market on firm
ground?” Austin American Statesman, August
26, 2007.
6. Huang, Jinlou (2009), p 67.
7. Givoni, B, p 291.
Conclusion
8. Ibid, p 292.
Sustainable design practices need
not be technologically complex or
necessarily expensive to implement.
Of particular interest is the scenario
where a positive environmental impact in one area works in symbiotic
relationship with another positive
impact. The hypothetical case study
of a high-rise Austin condominium
tower illustrates such a relationship.
By including a green façade and
meeting its need for adequate water,
we also manage a significant drop in
the amount of gray water introduced
into the sewer system.
9. Huang (1987), p 1104.
If Austin is to meet its goal of 25,000
downtown residents by the year
2015, it is essential to find and
exploit as many such symbiotic,
sustainable design practices as possible. Not only are such practices
environmentally responsible, but
19. Givoni, p 291.
10. Ibid.
11. Ibid, p 1106.
12. Ibid, p 1107.
13. Ibid, p 1113.
14. Dunnett, Nigel and Noël Kingsbury, p 192.
15. Ibid, p 2.
16. Ibid, p 239ff.
17. Ibid, p 66.
18. Ibid, p 195.
20. Ibid, p 292.
21. Ibid, p 291.
22. Ibid.
23. Schmidt, Marco, p 1.
Green Walls and High-Rise Residentiall: A Strategy to Increase Urban Vegetation
24. Ibid, p 3.
25. Ibid, p 8.
26. Ibid, p 6f.
27. http://www.nrel.gov/gis/solar.html
28. Dunnett, p 302.
29. Ibid, p 194.
30. Santamouris, Mat, p 111f.
31. Huang (1987), p 1105.
32. Lalic, Branislava and Dragutin T. Mihailovic, p 641.
33. Sonnentag, O, p 350.
Figures
Figure 1: From the website of archdaily.com,
http://www.archdaily.com/10685/consorciobuilding-concepcion-enrique-browne/
Figure 2: From the April 2, 2008 presentation
on a downtown condominium study, Capitol
Market Research, http://www.downtownaustin.
com/downloads/DTAustin_CondoStudy_
20080402.pdf
Figure 3: From the website of Capitol Greenroofs, http://capitolgreenroofs.groupsite.
com/discussion/topic/show/146768
Figure 4: From the website of Landscape
+ Urbanism, http://landscapeandurbanism.
blogspot.com/2008/07/living-walls-systemsapproach.html
Figure 5: By the author.
Figures 6–11: From the website of the Institute
of Physics in Berlin-Adlershof, http://www.
gebaeudekuehlung.de/en/index.html
Figure 12: From Marco Schmidt, “Rainwater
harvesting for stormwater management and
building climatization,” Technical University of
Berlin, (draft).
Figure 13: Data courtesy of Stefan Bader,
University of Texas School of Architecture.
Figure 14: From the website of the Department of Horticultural Sciences, Texas A&M
University, http://aggie-horticulture.tamu.
edu/cemap/plumbago/plumbago8.html
Figure 15: From the website of Campo Verde,
http://campoverde.wordpress.com/2009/04/24/
Figure 16: From the website of World of
Stock, http://www.worldofstock.com/closeups/
NPF5594.php
Figure 17: From the website of the 360 Condos, Austin, http://360-nueces.com/
Modeling,” Journal of the Americal Meteorological Society, April 2004: 641–645.
National Renewable Energy Laboratory, http://
www.nrel.gov/gis/solar.html
Novak, Shonda. “Condo market on firm
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Figure 18: From the website of Urban Living,
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Renovitch, James. “Recreating the Domain,”
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Figure 19: From the website of austintowers.
net, http://www.austintowers.net/at/condos/
navigator_files/carousel_image_4_1.jpg
Santamouris, Mat (Ed). Environmental Design
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Figure 20: By the author.
Schmidt, Marco. “Rainwater harvesting for
stormwater management and building climatization,” (draft).
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