Green Roofs Taking Root in Outer Boroughs

By Richard J. Bocklett


On the grand opening weekend of September 29 and 30, visitors to the Queens Botanical Garden will witness an example of ecological and environmental innovation in green building construction, which is paving - or rather planting - the road to a greener New York. The decade-long, $22 million capital improvement program puts the new QBG Visitor and Administration Center, located at 43-50 Main Street in Flushing, at the forefront of public botanical gardens in the nation. The building is devoted to the highest sustainable environmental standards, and was the recipient of the federal government's prestigious Leadership in Energy and Environmental Design (LEED) platinum rating, the highest available.

Among the environmentally friendly features is the artistically crafted green roof on the center's auditorium, which slopes down to the garden's grounds in a seamless blend of architecture and landscaping. Adjoining the energy-generating, photovoltaic-paneled main building, this 8,000-square-foot green roof sports an array of native plant species, such as Little Bluestem Grass and Prairie Cropseed, which impedes building heat loss in winter and excessive solar heating in the summer.

"The typical tar roof building is almost a reservoir for heat, and that heat sinks into the structure, driving up cooling costs and fossil fuel use," explained Scott Stefan, the Garden's director of Marketing. "Meanwhile, the greenery here absorbs carbon dioxide, gives off oxygen, and purifies the air while also abating ambient temperatures." As part of the sustainability goal, the carefully selected plants are all native species that do not require excessive watering or pesticide use. The soil itself is not like the backyard variety, but rather a specially formulated mixture of lightweight soil and stones that will not stress the structure itself.

"The green roof retains the rain so there's no storm water runoff," Stefan added. "That's important with our overburdened sewer system, which when it overflows dumps raw, untreated sewage into Jamaica Bay and Long Island Sound." The greenery also helps insulate the interior from unwelcome, outside sounds. "Queens houses two airports," he added, "but the real noisy jets overhead are not heard at all inside."But QBG isn't the only organization, public or private, that is at the forefront of the green roof movement.

The 11,000-square-feet green roof of the Gratz Industries Building, 13-06 Queens Plaza South, is nestled between a highly urbanized system of rail and road links within view of the Queensborough Bridge. In spring of 2007, Greener by Design workers replanted the industrial green roof with hardy green and red sedum plants for an environmental impact experiment. One important measure - the shrubbery's capacity to reduce drainage from rooftops - is being closely watched by Department of Environmental Protection (DEP) specialists who operate the city sewer system.

Perry Winston of the Pratt Center for Community Development is the architect of record for Gratz. He stresses that green roof buildings are in the city's best interest, because they reducing storm water runoff - which as recent events will attest - often floods streets and clogs sewers. The roof also lowers ambient temperature in the urban "heat island" surrounding a large area of tar, asphalt and concrete buildings, while the oxygen-generating greenery reduces air pollution in general. "The cumulative result of a cluster of green roofs is like creating a new, mini-climate in the immediate neighborhood," he declared.

As far as footage and size of flat roofs, Winston said that Queens has the most in New York, and that the borough - and Long Island City especially - are prime green roof territory. "These industrial one- and two-story big boxes are all over the place, as seen by Google Earth," he said. Completed last fall, the splendor of the 35,000-square-foot green roof of the famed motion picture and TV production business, Silvercup Studios, 42-22 22nd Street, can be viewed from the Queensborough Bridge ramps, as well as from the number 7 elevated subway line. It is the largest green roof in New York, providing the visual pleasure of a roof garden with its 1,500 planters that contain some 20 species of flora.

Greg Loosvelt is an environmental specialist with Earth Pledge, a non-profit organization devoted to identifying and promoting sustainability technologies, and works with both the Silvercup and the Gratz buildings. He maintains that with highways, elevated subways, buildings, and hard-surface areas abounding, there's little green space for water to drain. So, he says, you must recreate that ground on the roof. Loosvelt explains that green roofs substantially lower summertime rooftop temperatures, which can reach 170 degrees or more.

In the process, the thermal temperatures caused by building and concrete concentration can be alleviated by three to five degrees. This will result in lower air conditioning costs and less demand for energy, equaling less pollution and purer air quality. With over 46 billion gallons of raw sewage dumped into New York rivers every year due to sewer overflows, all measures at water absorption help. Green roofs have been shown to soak up 70 to 80 percent of the rain that falls on them. Loosvelt offers a hands-on anecdote. "I spoke with the long-term maintenance manager of Silvercup Studios about the green roof concept," he recalled, "and he admitted, 'You were right, this thing works. Every time it rained around here the streets were flooded, but now the roof holds the water and we don't get that runoff any more.' I think that speaks a whole bunch for green roofs and demonstrates their value to the community."

Earth Pledge maintains a rooftop weather research station at Silvercup Studios and at the Gratz Buliding. "We're just completing a yearlong project at Silvercup, gathering and analyzing data to quantify the green roof technology benefits," Loosvelt said. "Our instrumentation is calibrating water runoff amounts and building temperature levels and energy consumption rates, as well as measuring wind, humidity and ambient air temperatures."

In 2004, the Ridgewood-Bushwick Senior Citizens Council sponsored extensive renovations on aging buildings in Brooklyn, including green roofs and other green technology. The Rheingold Gardens apartments, at the site of the old brownfield that housed the Rheingold Brewery, 533 Bushwick Avenue, is their Phoenix Award-winning green renovation and affordable housing complex. The National Home Builders Association formally recognized the project, as well, for its positive impact on the environment and long-term impact on the community.

"The planners wanted a high-quality townhouse development that had lots of exposure to greenery," said Magnus Magnusson, the principal architect. Leslie Ackerman, executive director of Earth Pledge, says cost-benefit analysis show that green roofs can lower energy bills by as much as 30 percent. And, she sees Queens as an especially ripe area for green roofs. Unlike Manhattan's high-rise buildings and skyscrapers with small roof areas and big heating and cooling requirements, the outer borough's plethora of one- and two-story businesses and warehouses are the types of structures that could save the most on energy costs with green roof technology. Ackerman stresses, however, that a green roof is more than just a roof garden. It is a roof with a planted area either in a layered, integrated application or in modular design - like tiling the surface with pots. It is highly functional and built to specification of carefully selected greenery.

As a rule of thumb, the cost of green roof installation runs about $15 to $25 per square foot, depending on type and sophistication. Conversely, a standard roof comes with a price tag of about $10 to $12 per square foot. Obviously, a logical time to consider installing a green roof is when the present roof needds to be replaced, but Ackerman warns that before attempting even a small green roof project that thorough research be done and professional advice sought. Kubi Ackerman, an environmental specialist with the Urban Design Laboratory at Columbia University's Earth Institute, admits that green roofs are more costly to install than traditional ones, but can result in large savings in energy and repair bills over the long haul.

"Green roof life span is greater," he said, "because they are better at weathering the effects of heat and cold than standard tar roofs. Their longevity can be twice as long as traditional roofs." Ackerman said that contractors specializing in green roof technology can build or retrofit a green roof on almost any flat roof surface, including brownstones, apartment buildings, factories or - the institute's particular area of interest - school buildings. They also study the clean air health benefits, especially for areas with heavy incidences of respiratory illnesses, and the biodiversity effects for the neighborhood, as well as the hands-on educational opportunities open to pupils from schools with green roofs.

Adam Freedman, of the New York Industrial Retention Network (NYIRN), stresses that "energy and environmental conservation" are the buzzwords of the time. "Companies want to market themselves as being green," he says. "As a developer, you want to show you've done everything to foster green innovations and products." And in the process, he added, "we want them to lower their costs and to grow, thereby helping keep blue-collar jobs in the city." New York City gives tax benefits for green roof construction projects targeted at larger-roof buildings like factories and apartment houses. Benefits are calculated as a percentage of increased assessed value.

"Everyone has to work out the numbers for themselves," explained Freedman. "How much are we saving on energy costs and triggering tax benefits?"Leslie Ackerman assessed the status of green roofs in the city on a positive note. "We're not doing too badly in New York," she said. "The good news was Mayor Bloomberg's promised tax abatements of up to 35 percent of installation costs of extensive green roofs on new or existing buildings in his PlaNYC announcement."

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