Located on the rooftop of the headquarters of the American Society of Landscape Architects in the heart of Washington D.C., the ASLA Green Roof project transformed an existing 3,000 square foot roof into an expressive display of green roof technology that supports an active social space.
The barrel-shaped mounds at the north and south ends of the roof create new horizons for visitors, clearing the immediate urban foreground and focusing views on the more distant Washington skyline. The two lightweight mounds present two different green roof types: one is “extensive,” including low plants that require minimal soil depth; the other is “semi-intensive,” involving taller plants that require a deeper soil base. The higher growth on the semi-intensive mound rises up to meet the parapet edge and is visible from the street level, announcing the green roof and ASLA’s green agenda to public passersby. Balancing social use and ecological benefit, the main central walking surface is a metal grille suspended above a layer of living plants.
The Green Roof will be a demonstration project for future ASLA efforts to teach the benefits of green roof technology, and so it is designed with research and education in mind. The plant palette is more ecologically and environmentally varied than the sedum monoculture that is typical of many green roofs. The success of each plant species is being monitored in order to identify a more diverse palette of plants that could survive on an urban rooftop without active maintenance after the first several years of establishment. Monitoring and recording elements will also track the absorption of water and the temperature of the rooftop.
The ASLA Green Roof received a 2007 New York ASLA Design Honor Award
ASLA Green Roof