In a report published in the journal Sensors last year, Gaffin provided sample data collected from five green roof research stations in the New York City area (including Con Edison's) constituting a prototypical "urban meteorological network". The results showed that the mitigating effects of green roofs do exist, and can be accurately measured. Gaffin suggests that measuring these effects will be important for urban policymakers comparing the costs and benefits of different alleviation strategies.
But the most meaningful measure of the Con Edison roof's efficiency for Gaffin is not numeric. "It's fun to hear [the engineers] say they don't have to replace the filters on the air-conditioning system as much anymore," he says, explaining that, at least anecdotally, the building's air quality has noticeably improved since the roof was installed in 2008. Ultimately he hopes to quantitatively measure the quality of the air and water on the green roof’s surface.
Gaffin says unwarranted fears of waterlogged, leaky roofs also stand in the way of buildings roofing green. "The Museum of Modern Art got convinced to try it, but they were very nervous about it because they were thinking about their Picassos," he jokes. But he insists that green roofs are the safest, most protective, longest lasting and least risky roofs you can get. "Black roofs," he says with a grimace, "they're not even good roofs!"
Several rooftops around the city have gone green, including ones covering schools, museums and even Silvercup Studios in Queens—home of The Sopranos set. The Mayor's office roof has gone white—better than black in the summer but arguably worse in the winter, Gaffin says. And whereas white roofs may help cool cities, according to a study recently accepted for publication in Geophysical Research Letters, they don't do anything for storm water runoff.
In addition to their measurable environmental effects, Gaffin says biophilia—the love of living systems—and the therapeutic value of natural spaces is another, more qualitative incentive for green roofs. "I visited my mother-in-law recently in the hospital and she was looking onto the bleakest roof," he says, describing the blighted, garbage-strewn surface. "And I was thinking: 'Now if that was a green roof…'"