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May 16, 2005
Green Roofs Come to Washington
Green Roofs for Healthy Cities conference mixes
practical education with eco-evangelism.
By any standards, the Green Roofs
for Healthy Cities conference, held in Washington earlier this month,
was a small conference. But what it lacked in size, it certainly
made up for in the fervent belief that green roof technology can
change the way people think about green space and improve the deteriorating
quality of our environment by helping to stem water runoff, cut
down on green house gasses, and reduce the “heat island”
effect felt in many large cities today.
In fact, to hear the organization’s president Steve Peck tell
it, green roofs are just one part of a new movement that will change
the way we think about the interaction between the built environment
and the natural environment.
“We need to go beyond the already well-established green technologies,
to technologies that actually heal a building’s occupants,
cities, and the Earth,” Peck, a true eco-evangelist, said
during his opening remarks at the conference. “We need new
economic models that value natural resources. We need buildings
that provide sources for clean water and energy and can reconnect
humans with nature. We need restorative, environmental design forms.”
Green roofs, he added, are just the first step in this process.
Beyond the opening session, however, most of the talk at the conference
concentrated on attempts to quantify the environmental benefits
of green roofs, educate participants about their design and installation,
and discuss policy options that can be implemented to promote green
roof technology.
Green Roofs International
Green roofs may be just getting into gear here
in the United States, but as the conference clearly demonstrated,
they have definitely caught on around the globe. The staggering
fact that the country of Singapore has a smaller land area than
the green roof area of Germany should tell you just how developed
the technology is in Europe. (That comparison, by the way, comes
from Angela Sai of Singapore's National Parks Board, who gave a
wonderful presentation on a test roof in her home country.) Throughout
the conference, presenters gave details on green roof projects in
countries ranging from the aforementioned Germany and Singapore,
to France, the United Kingdom, The Netherlands, Mexico, and yes,
even the United States.
Covering the United States, Barbara Deutsch,
ASLA, of Casey Trees Endowment Fund, presented a study on the re-greening
of Washington, D.C., highlighting how green roofs can help alleviate
the twin problems of poor water and air quality. Noting that none
of Washington's three major waterways currently meet EPA standards,
Deutsch said that extensive green roof coverage in the city can
help cut down on stormwater runoff that often goes untreated. Deutsch
also said green roofs should help improve the air quality of the
city, which is partially responsible for one of the highest asthma
rates in the country and is directly responsible for costing the
city $120 million in federal highway subsidies every year. Deutsch
said Casey Trees is pushing a 20-20-20 initiative in the city, hoping
to have 20 million square feet of green roofs in Washington, covering
20 percent of the built footprint in 20 years.
Later, Casey Trees invited journalists and the deputy mayor of Toronto
onto its roof to view the building’s 3,500 square feet of
extensive green roof. “Extensive” green roofs cover
large areas of a roof, require little to no maintenance, and are
not considered decorative. Casey’s is one of the first green
roofs on a commercial building in Washington, and is currently the
largest extensive roof in the District. It was built in five weeks
and includes an electromagnetic leak detection system. It serves
as a good example to the rest of the city, which Casey Trees expects
will have 200,000 square feet of green roof installed in the next
year.
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views from the Casey
Trees green roof |
How Do You Get That Thing Up There Anyway?
It’s all well and good to have green roofs
popping up all over the world and even better to have them popping
up all over the country—but what about the practicalities
of building a roof? How, exactly, do you get that thing up there?
This was the very issue tackled by Jeffrey Bruce, FASLA, Chuck Friedrich,
ASLA, and Dave Honza during one of the sessions of the conference.
Bruce discussed the complications of building a roof with a team
that can include architects, landscape architects, general contractors,
roofers, and, of course, property owners and clients. He said that
the specialization required to install a green roof will often result
in the “stratification” of the trades, which means each
project must have a clear leader and timetable, as well as buy-in
from the property owner. He added that landscape contractors, who
are used to working with two feet firmly planted on the ground,
can often be apprehensive about working on a green roof, and that
education and training are essential when dealing with contractors
who are new to green roof systems. After Honza discussed the various
options for waterproofing the roof, Friedrich spent most of his
time talking about the soil, or media, that is used on the roof.
Because green roofs essentially create a microclimate, Friedrich
said the most important job of the substrate used on the roof is
to create deep root systems and channel water from the surface of
the roof down to that root system.
Friedrich’s six essential properties of the
media are:
- Drainage and aeration
- Water retention capacity
- Nutrient retention capacity
- Permanence
- Weight
- Stability
Remembering Design
The economic and environmental benefits of green
roofs were so highly touted throughout the conference that it was
possible to overlook the aesthetic and humanizing benefits they
provide. Lest attendees forget these less tangible but equally important
qualities, Cornelia Hahn Oberlander, FASLA, was there to remind
them. During a presentation aptly titled “Aesthetic Design
and Green Roofs,” Oberlander told a packed convention hall
that, “landscape architects should rise to the challenge of
strong and interesting roof design. The roof,” she added,
“can be a canvas.” Oberlander said that while the environmental
benefits of a roof can be great, landscape architects should not
forget the roof’s power to “humanize a city and come
closer to nature.” She then proceeded to show the audience
exactly what she was talking about in a series of slides of the
stunning green roofs she’s done for projects ranging from
the Canadian Embassy in Washington, which features hanging gardens
as well as a roof garden; to Library Square in Vancouver, Canada,
which she described as a “no fuss, no mess” garden;
to the Ontario Provincial Government Complex, a three-block project
encompassing 300,000 square feet of garden space. This project is
about to be rehabilitated, Oberlander added, meaning that plantings
will be deep-root pruned and the park will be dug up in order to
replace the roof underneath. It will then be replanted and reconstructed.
During the same session, Virginia Russell, FASLA, and David Whittaker,
ASLA, presented on a landscape Whittaker installed at a Cincinnati-area
water treatment plant, demonstrating water runoff and various ways
runoff can be stemmed. The “headwaters” of the demonstration
system was a green roof, and the landscape featured other water-runoff
barriers, including cisterns, porous concrete, constructed wetlands,
and retention ponds. The methods amount to a chain of stormwater
management that can be shown to developers and others to educate
them on methods of stemming runoff. The site also has a demonstration
park that shows schoolchildren how runoff moves from towns to the
nearby river.
But it's not just roofs that can be green these days, as Randall
Sharp, ASLA, of Sharp & Diamond Landscape Architecture &
Planning aptly pointed out in his presentation on living walls.
In keeping with the unofficial theme of the convention, Sharp took
the international approach, detailing living walls projects in Malaysia,
France, Germany, Costa Rica, Canada, and other countries. In what
could be the future of green building, he showed various examples
of green facades, ranging from screens that connect green roofs
with surface level gardens, to a sound barrier that he described
as a "green roof turned on its side," which can absorb
sound more effectively than the standard concrete blocks that currently
line our highways. Sharp is in the process of designing living walls
and screens for the Vancouver Aquarium that will not only provide
a visual demonstration of sustainability, but will also provide
food and habitat for the aquarium's fresh water fish, and in some
cases siphon off water that will be used for flushing toilets.
And
the Awards Go To…
Every self-respecting design association has its own awards,
and Green Roofs for Healthy Cities is no exception. The Green
Roof Awards of Excellence were handed out during the convention,
and here are the winners.
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North Beach Place,
San Francisco |
Cathy Garrett, ASLA, received
the award in the Intensive Residential category for her garden
at North Beach Place in San Francisco. The garden is part
of a new, mixed-use development that includes several courtyards,
play areas geared toward children of different ages, and a
special childcare area.
Terry Guen Design Associates, Inc.,
was honored in the Intensive Industrial/Commercial category
for Millennium Park in Chicago. The 24.5-acre park is perhaps
the largest green roof project in the world and includes 900
trees, shrubs, groundcover, perennials, and annuals. It includes
a growing medium that absorbs and polishes storm water, cleans
the air, and reduces the urban heat islands, not to mention
the numerous social, cultural, and economic benefits that
go along with a world-class city park. Jeffrey L. Bruce and
Company was the project manager for the park.
Building Logics, Inc., received
the Extensive Residential award for their Yorktown Square
Condominiums project in Falls Church, Virginia.
The Garland Company, Inc.,
received the Extensive Institutional award for its roof at
Evergreen State College in Olympia, Washington.
Roofscapes, Inc., received
the Extensive Industrial/Commercial award for its roof at
the Heinz 57 Center in Pittsburgh, Pennsylvania.
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