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Green Roof
Green Roof Performance Data
  • Roof produced a 10 percent decrease in building energy use over the winter months.
  • The temperature on the green roof on the hottest summer days can be as much as 59 degrees cooler than conventional roofs on neighboring buildings.
  • During a 10–month monitoring period, ASLA’s green roof prevented 27,500 gallons of stormwater — nearly 78 percent of all precipitation hitting the roof — from flowing into D.C.’s overburdened sewer and stormwater system.
  • Water quality testing shows that the water runoff contains fewer pollutants than typical water runoff.  Most significantly, the roof is reducing the amount of nitrogen entering the watershed.  
  • Except during repeated heavy rains, the roof only creates runoff during rainfalls of more than one inch.

Synopsis of Performance

Full Report

Sustainability with Style: The ASLA Headquarters Green Roof, by Nancy Somerville, Hon. ASLA and Chistopher Counts, ASLA