- The Washington Times - Thursday, September 20, 2007

Part of the solution to pollution and flooding from D.C. storm-water runoff is up on the roof, according to a new report.

As much as 10 percent of the water that now gets funneled into sewers and rivers around the District could be absorbed on roofs of buildings if more owners plant vegetation on them, according to the study released yesterday by the American Society of Landscape Architects (ASLA) in conjunction with Howard University.

“Both green roofs and trees decrease the volume of runoff, reduce rates of runoff and improve water quality,” ASLA said in its report.

Green roofs refer to buildings with plants on top of them to provide insulation and capture rainwater.

Washington is running a close second to Chicago as the city with the largest amount of green roof space.

The District had at least 301,751 square feet covered by green roofs in 2006, according to the environmental group Green Roofs for Healthy Cities. Chicago had at least 358,774 square feet of green roofs last year.

“They were the innovators,” said Jim Lapides, ASLA spokesman.

Chicago urban planners started promoting green roofs after a July 1995 heat wave that filled city morgues with the bodies of 525 mostly elderly persons who succumbed to triple-digit temperatures.

Insulation from green roofs cools buildings in the summer, reducing the “heat islands” that cement, stone and roof tiles normally produce in cities. Green roofs also keep out cold weather in the winter.

The District’s primary motive for promoting green roofs comes from the roughly 2.5 billion gallons of untreated wastewater and storm water that enter the D.C. Water and Sewer Authority (WASA) system each year. WASA estimates nearly $3 billion in upgrades are needed to reduce overflows and treat the wastewater.

Tests on a 3,000-square-foot green roof on top of the ASLA building at 636 I St. NW showed that extensive sewer upgrades could be reduced in size if more building owners planted rooftop vegetation.

The roof, which is planted with goldenrod, butterfly weed, cactus, sumac trees and other plants, can absorb an entire 1-inch rainfall, the researchers said. Over the course of a year, the roof can absorb 74 percent of rainfall while filtering out pollutants such as nitrogen and phosphorous.

Water absorption varies with the depth of the soil and varieties of plants.

The green roof on the new Bureau of Alcohol, Tobacco, Firearms and Explosives headquarters at 200 Florida Ave. NE was landscaped with native grasses, red maple trees and small bushes.

However, green roofs cost money to plant and require more maintenance than standard roofs — obstacles that must be overcome before they are widely accepted by developers.

“There is a perception that they are too expensive and impractical,” said Lex Birney, chief executive officer of Brick Companies, an Edgewater, Md., developer that specializes in green buildings.

Unlike most roofs, they require occasional weeding and watering.

ASLA estimates green roofs can cost $8 to $20 per square foot to install, depending on the plants used and the complexity of the landscaping. They are less expensive if they are included in the original building design.

The price is “roughly twice the cost of a normal roof,” said Steven Peck, president of Green Roofs for Healthy Cities, a Toronto environmental group.

ASLA spent $330,000 to install its green roof in April 2006 but hopes to recover the cost from lower energy bills and a roof that will last longer because vegetation and soil protect it from the elements.

Designers for the green roof had to overcome delays and misunderstandings from the permits division of the D.C. Department of Consumer and Regulatory Affairs, ASLA officials said.

“They’d just never seen a project like this before,” said Nancy C. Somerville, ASLA chief executive officer.

However, the D.C. government is becoming more receptive to green roofs, she said.

“We’re fortunately getting to a very different place in terms of how people view this, including the development community,” Miss Somerville said.

Last week, D.C. Mayor Adrian M. Fenty said he is organizing a “Green-Collar Jobs Advisory Council” to create jobs linked to the city’s green building policies.

Late last year, the D.C. Council passed legislation requiring all new local government buildings to meet environmental building-industry standards, beginning in 2008. Green roofs are one of the features that can help buildings meet those standards, which were developed by a consortium of building industry and environmental groups.

By 2012, all new public and private buildings in the District larger than 50,000 square feet must meet the green standards.

An office building under construction at 700 Sixth St. NW was designed with one of the Washington area’s largest green roofs.

“Green roofs serve as a great amenity to our users,” said Dodd Walker, development manager for real estate firm Akridge, which owns the building. Redevelopment is scheduled for completion in April 2009. He said most tenants like the plants on their roofs.

The roof is being planted with 12,000 square feet of sedum— small plants with overlapping leaves and flowers.

They never grow more than a few inches tall and require little maintenance.

“The rainwater takes care of them,” Mr. Walker said.

LOAD COMMENTS ()

 

Click to Read More

Click to Hide