Thursday, May 26, 2011

Going White

If you've ever looked at the rooftops of buildings or residential homes, more often than not you're going to find dark roofing materials, whether it is tar flat roofs or dark asphalt shingles. The dark colors retain heat, making cooling costs higher than they would otherwise be in the summertime.

New York City is urging building owners to go ahead and paint their rooftops white, which should bring down cooling costs considerably.
Buildings Commissioner Robert LiMandri set out to change that Wednesday morning, as he and his staff coated the roof of the seven-story building in a reflective white sealant. The special paint is designed to bounce the sun’s rays and reduce energy costs.

“If enough people do it, we’ll actually make a big difference,” LiMandri said when he took a break from painting the 22,500-square-foot roof.
Buildings Commissioner Paints Rooftop White to Cut AC CostsA painted section of the roof dried in the sun Wednesday morning, overlooking the Frank Gehry-designed Beekman Tower. (DNAinfo/Julie Shapiro)

In neighborhoods with lots of tar roofs, such as lower Manhattan, Long Island City and Greenpoint, the reflective paint could even reduce the temperature down on the street, LiMandri said.

The sealant costs 30 to 40 cents per square foot, and it could cut air-conditioning costs in half for single-story houses with flat roofs. Two-story houses could see a 25 percent reduction in cooling costs. The sealant also protects roofs and helps them last longer.

One downside of the reflective paint is that it slightly increases a building's heating cost in the winter, compared to a standard black tar roof. But that increase in cost is easily offset by the savings on air conditioning in the summer, a DOB spokeswoman said.

The city hopes to have 1 million square feet of rooftops coated by this fall.
While the heating costs may rise, the cooling cost savings should more than offset the higher winter costs (and as is often the case, the rooftops are covered in snow for portions of the winter in any event. This is hardly the first time that this has been proposed, President Obama's Energy Secretary has backed the idea, and I made sure that when we replaced our own roof, we opted for the lightest color available to take advantage of lower energy costs during the summer.

It's a relatively low cost change if you have an existing roof, but doesn't add to the costs if you're putting on a new roof. Yet, the cost savings could be considerable over the life of the roof, and it is likely to make for a more comfortable building and local environment.

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