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Washington, D.C. 

The Sidwell Friends School’s 15-acre campus sits on a ridge between two watersheds which flow through steep parks to the Potomac River. Owing much to the design of site and landscape, the renovation and extension of the Stewart Middle School building is the first LEED platinum-rated K-12 school building in the world. In addition to the environmental benefits of superior conservation of energy, water and materials, students and teachers benefit not only from modern educational spaces, but from a building based on a sustainable concept. As the building is also used to teach environmental awareness, students observe and analyze their relationship with natural resources, the local habitat, and the built environment.

Completed in 2006, the project reuses and expands the original middle school building, a plain structure dating from 1950. The design of the site began with the decision to save and reuse this older building, and concentrating development on a single part of the campus – conserving open land, a scarce urban resource. The location and orientation of the new construction optimizes the use of daylight within the building. A car parking area has been tucked under a vegetated “green” roof, which reduces runoff by absorbing rain water and lessens the “heat island” effect, compared to exposed paving.

The design places an emphasis on water cycles along with connections to local geology and habitats. The U-shaped building surrounds a courtyard that has a man-made wetland that cleans and recycles wastewater from the building for reuse, and a separate pond that captures stormwater for landscape irrigation. In response to the sloping topography of the site, the wetland resembles terraced rice paddies. The natural system is a demonstration of the food-waste-food cycle, as micro-organisms decompose the wastewater as it moves through the wetland. The treated wastewater is returned to the building and used for toilets and cooling systems. The quantity of water that is recycled allows for an equivalent reduction in the amount of city-supplied water used, and contributed to the sewerage system.

Rainwater is held and filtered by the vegetated roofs on the additions. All water on both existing and new wings is diverted to the courtyard side of the building through a series of scuppers, downspouts, gutters, and spillways to a pond which will support native habitat. The green roofs are also used as garden spaces where students grow vegetables for the cafeteria.

In addition to the wetland, the design of the landscape introduced more than 80 plant species to the site, all native to the Chesapeake Bay region. They promote biodiversity of native animal species, and require minimal irrigation to thrive.

Besides the features of site and landscape, the building employs a variety of sustainable strategies that contribute to its outstanding green performance and rating. Solar photovoltaic panels on the roof provide about 5% of the building’s
electricity. Windows are shaded from summer sun with wooden slats. These slats are made from recycled wood (from 100 year-old wine casks), and many other building materials are recycled or naturally renewable. The use of natural daylight and advanced, automated lighting controls saves 10 – 15% of electricity used for lighting. Natural ventilation reduces the need for mechanical cooling. The list goes on...

By using the building and grounds as an object lesson to educate students, those involved with the project hope it will bring a lasting change that will have an impact far beyond the Sidwell campus. “We feel that a lot of these young people are going to be in the position someday to have a major impact,” the school’s headmaster has said.