One year after being constructed, the Washington International School’s green roof is flourishing. As part of an addition to the elementary school, the green roof, nearing full growth, brings added sustainability to the building. BGA Project Manager Stuart Billings, AIA, LEED® AP BD+C, completed a post-occupancy evaluation to ensure that the addition is performing as designed and found it has been very successful.
Washington International School undertook the project to create gathering spaces and music facilities for students. The lower level gymnasium previously had been used as the cafeteria, movement space and auditorium, causing a schedule overload.
The addition provides music rooms, a technology studio, a large multi-purpose classroom and a meeting room. A second staircase improves circulation between the gymnasium and other student facilities. A new full-length corridor runs from the entry to the outdoor play area, establishing a greater connection between the play area and the rest of the building. Art and science classrooms look out onto the green roof, which brings inspiration to class discussion and student projects.
Sustainability measures such as green roofs are a vital part of every project, regardless of whether the team is seeking LEED Certification. Green roofs can have a substantial effect on the immediate environment. The addition’s roof is only 3.5 inches deep, requiring specialized soil and plants such as sedums to minimize water damage. The plants, largely sedums, were chosen to fit the District’s temperate zone. Sedums store a lot of water in their leaves, making them drought tolerant and cost-efficient as they are self-sustaining without irrigation. The plants also soak up between 50 and 90 percent of stormwater, minimizing the run-off that can lead to erosion and localized flooding during storms. Plant life improves the quality of the water and ensures that the water which does reach the Potomac River is much cleaner.
The green roof also acts as an insulator for the building and lowers the energy costs of heating and cooling. The roof is part of several other sustainability initiatives, including the use of rapid renewable materials sources and linoleum. The project was designed to the US Green Building Council’s LEED® standards.
Bowie Gridley Architects has utilized green roofs on several other projects, including Roland Park Country School and the library at George School. The library is situated downhill from the main campus buildings, and the green roof allows the library to blend into the surrounding campus landscape. Sustainability is a prominent feature of the facility, with a sample garden in the lobby of the building to show students how it works. A LED display also shows how efficient the building is throughout the day.
