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…'"
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Add CommentChicago has started doing this and the benefits are many - including reduced heating costs in winter, reduced cooling costs in summer and, of course, whatever is grown on the roof.
Reply | Report Abuse | Link to thisNothing beats going green and saving $$$.
Green roofs cost a fortune to build, and once they leak and they will they are a nightmare to repair, actually you have to remove the whole roof to repair because you just end up chasing leaks forever. I would compromise with a white roof and solar panels.
Reply | Report Abuse | Link to thisDoes the addition of a green roof to an existing building result in a corresponding reduction of its safe snow loading? Just wondering whether a few inches of wet green stuff and water-saturated soil would be a problem under a winter snowfall. Wet turf is heavy.
Reply | Report Abuse | Link to thisAll of that runoff cleans the streets and flows into streams after treatment. Green Roof=Dirty City? Green Roof=Dead Fish. What do the weeds that grow when the green roof is not maintained do to asthma sufferers? Green Roof=Lawsuit?
Reply | Report Abuse | Link to thisMy roof is white. Chosen to be that color in part to reduce summer heating and in part to reduce global warming.
Reply | Report Abuse | Link to thisWhy don't building codes require that homes be oriented so that they can be efficiently retrofitted with solar collectors?
The major impediment to change is inadequately and inappropritely designed infrastructure.
It's not rocket science people.
"All of that runoff cleans the streets and flows into streams after treatment." - Skeptic
Reply | Report Abuse | Link to thisAhhh... No... It flows into streams <BEFORE> treatment.
Rainwater is used to purge sludge from sanitary sewers, and typically treatment facilities are not capable of managing all of the runoff from a rainstorm so much of it is simply dumped raw into lakes and streams.
How odd that yet another Skeptic finds himself detached from the reality of things.
I fixed many problems with my roof like leaks, heat and constant cleaning by constructing a cheap wood and plastic greenhouse. That might be a good option with the same benefits.
Reply | Report Abuse | Link to thisI understand that the embedded energy of the additional material needed to support a green roof substantially adds to the lifecycle environmental footprint of a greenroof. If that is right, it seems like the choice between them and white roofs would be between priorities, where green roofs provide better stormwater management and aesthetics with a higher environmental impact than white roofs.
Reply | Report Abuse | Link to thisiamdata,
Reply | Report Abuse | Link to thisYour statement is intriguing if not explanatory. Pray tell how the construction of a cheap greenhouse cured your house roof's shortcomings.
It's not rocket science people.
Reply | Report Abuse | Link to thisActually, it's as complex as one might like. The choices are wide - solar heating, photovoltaics, white metallic roofing panels, shading trees, roof succulents, etc, etc and mixes thereof. The variables of geographic location and zoning rules add to the complexity. Bring in the biological questions and the complexity goes way beyond rocket science.
The greenhouse was constructed on top of my house so I dont have the rain falling directly on the concrete roof. I made its roof with white translucent plastic which allows light for the plants but blocks a lot of heat. There is also a lot of shadow provided by the pots and hydroponic systems. But the biggest benefit is saving money on food.
Reply | Report Abuse | Link to this"Actually, it's as complex as one might like" - Quasimodo
Reply | Report Abuse | Link to thisAnd none of the "complexities" you mentioned have anything at all to do with orienting homes so that they can be easily be retrofitted with solar collectors. You face the largest face of the roof south, and design your subdivisions accoringly.
It's not rocket science People.
...Rainwater is used to purge sludge from sanitary sewers...
Reply | Report Abuse | Link to thisNot unless the sewer system isn't working right. Sanitary sewers carry sanitary waste, storm sewers carry runoff. Combined sewers carry both. You are describing a combined system, common in older cities and city centers here and abroad.
I've been building green roofs for 12 years a long time in the US, they have been around in Europe for over 5o years. done right, they prevent leaks and wear of the roof, weight can be controlled by the type of media used and doesn't have to add to the structural cost, they very effectively filter pollution from rain water and delay and/or eliminate run off from storm events mitigating the overwhelming of storm sewers. Cost - can be recouped over time in real terms. problems caused by paving over the environment aren't considered in building costs, if they were, green roofs would be a big savings.
Reply | Report Abuse | Link to thisThey aren't the magic pill some claim but there are quantifiable, real benefits and they look great.
If you have had problems with your green roof it probably wasn't designed and/or installed right. Call me next time!