The leafy rooftop of the American Society of Landscape Architects building in downtown Washington is a model of the techniques used increasingly to cool temperatures, filter air, and lessen the burden on sewers by absorbing rainwater.While green roofs are certainly catching on in the US, we're still lagging behind countries like Germany that have been installing them since the '50s:
Visitors are surrounded on three sides by a variety of plants, and the aluminum grating that serves as a walkway is suspended over more vegetation.
Germany ... now has 50 square miles (32,000 square acres) of green roof space and adds an additional five square miles (13 square kilometers) per year, estimates Christian Werthmann, an assistant professor of landscape architecture at Harvard's Graduate School of Design.The new green roof on the ASLA will serve as a showpiece for the technology, and the organization clearly settled for nothing less than the cutting edge. What did they get for the $946,000 they spent?
Green roofs began to spread when some German cities encouraged building owners to substitute ballast and tar rooftops with vegetation. Werthmann estimates 40 German municipalities require green roofs in at least some cases.
The United States has only a fraction of the green roof space found in Germany -- but a study this month found U.S. green roof space grew 80 percent last year. North America has a total of 2,150,000 square feet (200,000 square meters), according to the study by Green Roofs for Healthy Cities.
Chicago was the U.S. leader, planting nearly 300,000 square feet (27,900 square meters) of green roof space last year.
- In order to provide the maximum environmental benefits a green roof can bring and the greatest green coverage possible, the roof design includes two waves covered with green roof systems, or specialized roofing systems that support vegetation growth on rooftops. Surrounding these waves are a third extensive green roof system, covered by a metal grating that allows visitors to walk over the plant material without damaging it.
- The roof also has an open pavilion that houses a stairwell for access and is covered with varying types of extensive green roof material. In front of the pavilion is a small observation deck.
- The use of grating over sedum for the central area and access path provides almost total green coverage for the roof.
Categories: greenroof, landscapearchitects, washingtondc