Tar Beach, those black tarred rooftops where regular New Yorkers got their summer tans, is celebrated in song, in movies like “On The Waterfront” and in a well-known quilt and children’s book by Faith Ringgold. But if they evoke the same kind of nostalgia as stoop ball and stick ball, those roofs turn out to be bad for the environment.
The asphalt and concrete trap sunlight and heat and contribute to what scientists call the “urban heat island” effect that makes the city as much as 10 degrees Fahrenheit hotter than the suburbs.
The difference in temperature translates into some $100 million in additional energy costs per year.
That is why a movement is growing to replace New York City’s iconic rooftops with something cooler, literally.
A cool roof, or “white roof” -- as simple as a basic coating of light-colored water sealant â€“ is the roof of the future in New York, says Laurie Kerr, an architect in the Office of Sustainable Design, the eco-
conscious division of New York City’s Department of Design and
Construction. “The city controls maybe one in ten buildings in terms of square
footage. Over the next 20 years, all of those buildings
should have cool roofs.”
But others are pushing an alternative -- a “green roof,” in effect a rooftop garden, with plants (even trees) atop a layer of soil.
Common in Europe, and growing more popular in American cities out West, green roofs remain a challenge in New York.
“Roof tops are an enormous wasted resource,” says Leslie Hoffman,
executive director of EarthPledge,
a Manhattan-based nonprofit that has helped build green
roofs atop eight local buildings, including the Rheingold Gardens
building in Bushwick, a 250-unit senior housing facility. Her
organization’s efforts are paralleled by Sustainable South Bronx, the
Hunts Point non-profit that recently opened a demonstration green
roof project atop the American Banknote Building. In an interview
with WNYC at the time of the installation, Bronx Borough
President Adolfo Carrion said the borough was home to at least nine
green roof installations. “We can’t force anybody" to install green roofs, Carrion said, "but we are
certainly creating incentives by saying we will be very supportive of
Expanding that support to the rest of the city could take some time. Green roofs, while attractive to look at and useful when it
comes to minimizing both heat and water runoff, are roughly five
times as expensive as the typical roof installation.
Cool roofs demand less of an investment
from private property owners and less paperwork for city contractors.
With the recent signing of a new law mandating that all major city-
funded construction and renovation projects meet energy conservation
standards laid out by the U.S. Green
Building Council, Kerr from the Office of Sustainable Design expects most projects to go with the easier
white roof method.
The Case For Green Roofs
Green roof advocates, meanwhile, are working hard to boost the
economic case for green roofs in the hopes of convincing city leaders
to set up incentives for builders and property owners.
“The problem is the reflective roofs don’t deliver one twentieth the
benefits of a green roof,” says Steven Peck, president of
Green Roofs for Healthy Cities, a Canadian
Peck points to green roof’s ability to limit storm water runoff,
something the city needs to do in order to bring its sewage system in
compliance with the Clean Water Act. The largest green roof on
record, a 10.4 acre installation at Ford Motor Company’s Rouge River truck factory, is expected to cut that facility’s storm water runoff -- and the resulting sewer bill -- in half. If New York City were
to take a cue from Portland and some European cities and charge
building owners for the amount of storm water they send into local
sewers, the return on investment issue would quickly balance out.
Peck also points to green roofs’ ability to filter pollutants and to
remove carbon dioxide via photosynthesis. Like their
counterparts in urban forestry, green roof promoters are
hoping to come up with models that put a dollar figure on such services.
Should those dollar figures become available, however, they might not
be enough to convince individual building owners to make the switch,
says Stuart Gaffin, a scientist at the Center for Climate System
Research at NASA’s Goddard Institute of Space Sciences. Earlier this
year, Gaffin served as host of a graduate seminar on green roofs. In their
attempt to put together a model on the environmental
benefits of green roof installation, however, they found most of the
benefits appearing at the societal level, as opposed to the
individual property owner.
“You try to get the economic benefits to the owner and you run out of
things pretty quickly,” says Gaffin. “There aren’t a lot of direct
Gaffin says he has deals with two
local schools -- one public, one private -- to install and monitor
green roofs. With these plots, he hopes to build up local data which
can then be used to convince the city council to offer additional
incentives for green roof owners.
Gaffin and his students are joined in their effort by Diana Balmori,
the architectural designer of the city’s largest green roof, atop the Silvercup Studios facility in Long
Island City. Built with the help of Earth Pledge and the New York
Power Authority, the installation is the first of what Balmori
expects to be two major installations in that neighborhood. Balmori
plans to use rainwater data from both installations to push city
leaders to follow in the footsteps of their Seattle and Chicago
counterparts and add green roofs to the evolving “green building”
“It would be really great if New York grew some industries around
this, but it hasn’t reached the critical mass to make it affordable
enough for the majority of the population,” Balmori says. “With just
some minimum incentives, that turnaround could happen. All we need is
that relatively small push.”
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