Buildings
ASLA Retrofits Headquarters with Green Roof
(archrecord.construction.com - 07/06/2006)
By Paul
Burkhardt
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| Photo
courtesy ASLA |
The American Society of Landscape Architects
opened a green roof on its Washington, D.C., headquarters
in conjunction with Earth Day this year. “We wanted to
show how you can maximize both the environmental benefits
and the aesthetic and amenity benefits of a green roof through
the landscape architect’s design,” said Nancy Somerville,
executive vice president of the ASLA.
The 3,300-square-foot roof, whose design
was led by New York–based Michael Van Valkenburgh Associates,
replaces a standard black tar surface on the 10-year-old brick
building. Visitors to the roof climb a staircase to reach
an aluminum-grate landing suspended above various succulents.
Sweet fern and fragrant sumac grow among other plants in deeper
soil on the roof over the staircase platform. Two formerly
imposing air return units are also hidden within slopes of
semi-intensive plantings that include African ice plants,
evergreen moss flox, and various leafy stonecrops, anchored
by a system of steel cables. “Having blooming plants
around you, at and above eye level is a very different experience
than having them just around your feet,” Somerville said,
adding that the roof feels cooler than neighboring roofs,
giving visitors an “oasis feeling.”
Roof accessibility was key but costly,
with a staircase and entryway taking up two-thirds of the
$950,000 budget: The narrow building envelope limited room
for construction staging and storage, thereby increasing labor
costs; ASLA officials also cite high materials costs in the
wake of Hurricane Katrina.
The ASLA has ongoing plans to monitor
the roof and share findings to help further green roof development:
flow-meters are being fine-tuned to gauge the roof’s
stormwater retention, and temperature readings will be compared
with those from an adjacent non-green roof.
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