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FEATURE ARTICLE, JULY 2005
THE ENVIRONMENTAL AND ECONOMIC ADVANTAGES OF
“GREEN ROOFS”
Stephen Lustgarten
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Lustgarten |
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The “green roof” phenomenon, which started in Europe, is catching on in the United States and gaining popularity in major urban centers. Green roofs feature soil, plants and alternative drainage in place of traditional roof materials to help with the reduction of storm water runoff pollution and energy costs. Green roofs cool the air and improve air quality, providing a solution to the “heat island affect,” a condition where urban temperatures are elevated above those in rural areas.
The surfaces that replaced trees in the development of a city — mostly sidewalks and rooftops — are impervious to rain water. Heavy rain can cause sewer pipes to become overwhelmed, leading to the discharge of untreated sewage into the region’s watershed.
A prominent example is the green roof that sits atop Chicago City Hall, which was installed after the heat wave of 1995 where 529 people died — fatalities blamed in part on the urban heat island effect.
Next to trees, green roofs are the best management practice to improve air and water quality in cities. An analysis of the downtown commercial core in Washington, D.C., showed that if 80 percent of the rooftop area became green roofs, storm water run-off could be reduced by 56 percent, making significant contributions toward solving the District’s combined sewer overflow problems.
My firm, Blake Real Estate, entered into a partnership with Casey Trees Endowment Fund and DC Greenworks to install the first green roof project in the Washington, D.C., commercial district at the 12-story 1425 K Street building. It has become a model for other developments in downtown D.C. More than 700 visitors have toured the project, it has received grants from the Washington, D.C., Department of Health and the National Fish and Wildlife Foundation, and generous sub-contractors supported the green roof project through discount pricing.
Notably, our green roof project recently won the “Environmental Impact” award as part of the Washington Business Journal’s Best Real Estate Deals of 2004 competition.
Once the project began, a waterproof membrane and root barrier and an electronic leak detection system were installed. A two-inch layer of polystyrene insulation was added, and 35,000 pounds of soil were lifted to the top of the building and spread three inches deep. Then, about 10,000 low-growing sedums, known for their heartiness and shallow root systems, were planted.
The 3,500-square-foot green roof serves as a research and demonstration project as well as enhancing tenants’ enjoyment of the rooftop terrace at the building. WRC-TV Channel 4, the local NBC affiliate, also is participating in the project by measuring the green roof’s reduced storm water run off, air pollution and rooftop temperatures. The project also will monitor the building’s energy costs, as savings are anticipated as a result of the affects of the green roof.
We held numerous meetings and conducted a great deal of research before deciding to move forward with the green roof project, which began last May. We were hesitant at first as we had just installed a new traditional roof, but now we are certainly convinced of the many benefits provided by a green roof.
Stephen Lustgarten is executive vice president with Blake Real Estate in Washington, D.C.
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