Parque Techo Verde en oficinas del servicio postal de USA

ORIGINAL: Dirt

U.S. Postal Service’s 2.5-acre Green Roof Park

07/30/2009 by asladirt

The New York Times wrote about the new 2.5-acre green roof on the U.S. Postal Service’s Morgan processing and distribution center near mid-town Manhattan. In addition to providing the usual benefits of a green roof, the U.S. Postal Service’s green roof also provides park-like recreational space for employees, including ”benches, billowing grasses and a view of the skyline that includes the Empire State Building.” According to The New York Times, the project was part of the broader Postal Service environmental program, which also includes expanding the use of hybrid vehicles and more energy-efficient buildings that produce less waste.

The New York Times argues that green roofs haven’t taken off as quickly in New York City as they have in Seattle or Chicago because the labor and transportation costs in New York City may be higher. High upfront costs, particularly related to the cost of soil, may also be limiting the spread of green roofs. ”In particular, the soil for the plants, which is engineered to be lightweight and absorbent, is extremely expensive. While a cubic yard of normal soil might be $2 or $3, the cost of the engineered soil and its installation is about $120 per cubic yard, said Elizabeth Kennedy, the landscape architect who designed the postal roof’s landscaping. The price for the project installation was about $30 per square foot.”

The cost of special lightweight soils, however, may be less than the cost of re-inforcing older buildings to withstand the weight of normal (less expensive) topsoil. The New York Times says different types of buildings have different threshholds for bearing normal topsoil weight: “The post office building, built in 1933 and declared a landmark in 1986, was constructed to support additional stories, and copper column tips still poke out from the roof. Depression-era government buildings are particularly well-suited to being adapted for green roofs, because they can support the additional weight, said Angie Durham of Tecta America, the company that designed the roof. By contrast, buildings from the 1970s and 1980s are not as architecturally well-suited for retrofitting, she said.”

To spur greater use of green roofs, the New York State Legislature passed a tax-abatement plan passed last year. Still, the postal service’s green roofs took two years for approvals.

Some of the key environmental benefits of the U.S. Post Office green roof park: “The new roof is expected to last 50 years, and it will provide better insulation, cutting heating and cooling costs by about $30,000 a year. In addition, the landscaping on the roof is expected to help reduce storm-water runoff into the sewage system by as much as 75 percent in the summer and 40 percent in the winter.” Additionally, low-maintenance, native vegetation was used, including ”coral carpet, John Creech, Weihenstephaner, Immergrunchen, Fudaglut and red carpet.”

Read the article and view more images at Inhabitat. Also, check out a World Landscape Architect interview with Elizabeth Kennedy, Principal of EKLA, the landscape architeture firm that designed the green roof.

In other news, the Toronto-based non-profit, Green Roofs for Healthy Cities, launched a green roof professional accreditation exam. Architectural Record writes: “The green roof professional (GRP) designation is not intended as a form of licensure or an indication of professional competency, but should facilitate improved collaboration among the various disciplines involved in designing and installing green roofs, according to Green Roofs for Healthy Cities.”

According to Architectural Record, the GRP exam, which cost $395 without the prep courses, will be offered in four North American cities this fall, starting with Toronto, on October 19. Test dates for Seattle, New York City, and Chicago have not yet been finalized. More information on the accreditation program can be found at www.greenroofs.org.

Learn more about the new GRP designation.