June 3, 2002

By Errol Louis
Staff Reporter of the sun

Never Mind My Valley – How Green Is My Roof
House-Top Gardens Emerge as Goal for City’s Eco-Activists

As the city begins its annual summer transformation into a stone-and-steel inferno, a consensus is emerging on a simple way to keep things cooler in Gotham—turn the city’s rooftops into gardens.

An unlikely alliance of more than 75 private companies, conservationists, public officials, scholars, and community activists announced plans on Saturday to blanket New York City with green roofs. The gathering, sponsored by the Earth Pledge Foundation, was the latest in a series of meetings designed to help Gotham catch up with cities like Portland, Toronto, Berlin, and Chicago that started green roof initiatives years ago.

“This is the beginning of a coalition,” said the organizer of the event, Cathy Ho. “We feel that New York is primed for a green roof initiative.”

The conference’s half dozen speakers emphasized a cooler city as the most attractive benefit of replacing the city’s tar, asphalt, aluminum and gravel roofs with plants, grasses, trees, and flowers. It’s estimated that New York, like other big cities, tends to be six to eight degrees hotter than the surrounding suburbs, a phenomenon called the urban heat island effect. Much of the temperature disparity can be traced to the city’s dark tar and gravel roofs, which soak up sunlight and throw enormous amounts of heat upward into the air and downward into buildings.

“We pay for the heat island effect during the summer, and we pay for it very dearly,” said Hashem Akbari, director of a study group on urban heat islands at Lawrence Berkeley National Laboratory. Mr. Akbari estimated that New Yorkers could save as much as $16 million a year in energy costs by establishing cooler, green roofs.

Linda Velazquez, founder and publisher of greenroofs.com, an electronic newsletter, estimated that a green roof can cut a building’s cooling cost by as much as 50%, a number that can vary depending on the size of the building’s roof. Ms. Velazquez showed examples of buildings that have installed green roofs, including the San Bruno, California, headquarters of the Gap clothing company and the Mashantucket Pequot Museum at Connecticut.

Conference participants applauded Ms. Velazquez’s photos of one of the premier showcases of green roofing, Chicago City Hall. It has a roof spanning half a city block that is covered with 20,000 different plant species. The roof cost $1 million. The mayor of the second city greened the roof in the wake of heat waves that caused the deaths of 376 Chicago residents in 1995 and 50 in 1999.

“Green roofs are exceptionally good at cooling cities,” said Steven Peck, Executive Director of Green Roofs for Healthy cities, a Toronto-based coalition of construction companies that manufacture and install green roofing materials. Several company representatives were on hand at the conference on East 38th Street, with slick color brochures advertising their services.

Installing a green roof isn’t a do-it-yourself job. A waterproof membrane has to be laid down and topped with a factory-made synthetic soil. Ordinary dirt is too heavy, and clogs the water draining system. Conference experts estimated the cost of greening a roof to range between $20 per square foot and $4 a square foot. Building owners at the conference Saturday emphasized that landlords would be hesitant to invest in new roofs without tax credits or other financial incentives, although the creation of rooftop gardens would partly offset the cost by increasing the value of the property.

The conference included an acknowledgement of the moves the city has already taken in the direction of green roofing. One of the speakers, Hilary Brown, served in the Giuliani administration as founder of the little-known Office of Sustainable Design within the New York City Department of Design and Construction. Under Ms. Brown’s tenure, the office published standards for what it calls “high performance buildings” that conserve energy, minimize storm water runoff and include green roofs.

According to Ms. Brown, who is now a private consultant, using green roofs significantly minimizes the pollution of city waterways. Rainwater drains quickly off traditional tar roofs, said Ms. Brown, which floods the city’s sewage treatment system and results in the discharge of raw sewage into the Hudson and other local rivers. Green roofs, by contrast, absorb nearly all of the rain that falls on them.

The various arguments for green roofs – lower temperatures, energy savings, cleaner water, higher property values, the creation of more green space – attracted conference participants spanning a wide range of interests and ideologies. Several city agencies sent representatives, as did conservation and design organizations.

“I’m interested in the importance of implementing green roofs all over the city,” said Margaret Fox, a member of the Green Party who volunteered for its nominee, Ralph Nader, in the 2000 presidential election. Ms. Fox, who works at the Brooklyn-based Pratt Institute Center for Community and Environmental Design plans to organize community-level discussion of green roofs in Park Slope, Brooklyn. “Park slope is ripe for green roofing,” she said. “I think the consciousness is there.”

At the opposite end of the political spectrum, Kalman Sporn, a conservative Republican investment banker who is running for the state senate from the west side of Manhattan, cited green roofs as a way to show private developers a way to improve New York’s quality of life while turning a profit.

Leslie Hoffman, director of Earth Pledge Foundation, predicted that the political diversity of her nascent coalition would prove to be its strength. After inviting participants up to the foundation’s brand new roof garden, atop a Murray Hill townhouse, she watered plants and mused about the movement the foundation is trying to create.

“I think that as New York City green buildings start to get more attention, others will want to have them too,” she said. “Somehow we have to incentivize people to do it, because there is a cost. But the social benefits are huge, and the benefits to the building occupants are significant. I want a significant percentage of New York City roofs to be green.”