Sourced from the Living Architecture Monitor
According to the Department of Energy and Environment (DOEE), as of 2017, there are currently more than 3 million square feet of green roof in the District. The rise in green roofs in DC can be attributed to the city's rigorous stormwater regulations and grant programs designed to provide incentives for the installation of green roofs. DC receives more than 40 inches of rainfall each year and with more than 43 per cent of the Districts land cover being impervious, a single 1.2-inch storm falling on the area can produce as much as 525 million gallons of stormwater runoff.
Over the years, the DOEE has been very successful in its green infrastructure policy creation and implementation. Stricter stormwater regulations were introduced, along with the Green Area Ratio, RiverSmart programs, and the Stormwater Retention Credit Trading Program.
In 2013, the DDOE released the 2013 Rule on Stormwater Management, Soil Erosion, and Sediment Control (2013 SWM Rule). The DOEE recognized soil erosion due to stormwater runoff as a key factor in decreased water quality in the Districts streams and rivers. In addition, the Office of Planning navigated the passing of the Green Area Ratio (GAR) through the Zoning Commission. According to the DOEE website, the GAR is an environmental sustainability zoning regulation that sets standards for landscape and site design to help reduce stormwater runoff, improve air quality, and keep the city cooler.
The DOEE also promotes stormwater management through its various RiverSmart Programs. RiverSmart programs provide financial incentives to help property owners install green infrastructures such as rain barrels, green roofs, rain gardens, permeable pavers, shade trees, and more. The rebate program, since its inception in 2006, offers a rebate of $10 – $15 per square foot for voluntary installations of green roofs and has greatly contributed to the installation of green roofs District-wide