“Cool Roofs” – A hot idea?

August 31, 2010 | 35 Comments

By Christopher Solomon of MSN Real Estate

'Cool' roofs – a hot idea? (© MCA Superior Roof Tiles; Custom-Bilt Metals)

Linda Hanson is accustomed to long, hot summers, and she wanted to find a new way to reduce her cooling costs.

Hanson owns a home in Canyon Lake, Calif. “The average temperatures out here are well in the 100s all summer long, so our (electricity) bills were $800 a month. It was pretty outrageous. We could not cool the house down. We’d run the air conditioner all the time.”

A big problem was the original concrete tile roof, which sat on the rafters and radiated that heat right into the house.

Then Hanson and her husband swapped out that roof for a so-called “cool roof” of green tiles on their 3,000-square-foot house. (They made other improvements, too, such as upgrading the home’s windows and adding attic insulation.)

“We also put a swimming pool in, and even with that swimming pool, with the filter running, our bills in the summer are probably 200 bucks a month less,” she says.

The best part, she says, is “my house is comfortable all the time.”

Hanson’s savings may be dramatic, but they illustrate the point: Installing a cool roof is a hidden-in-plain-sight way to cool your home, shrink your electricity bill and help the planet. It’s such a simple, smart idea that Energy Secretary Steven Chu endorsed the idea in a meeting with Nobel laureates last year. 

An old idea made new
Inhabitants of places such as Bermuda and the Greek isle of Santorini have long known that painting their roofs white to reflect sunlight can keep their homes cool. Studies bear that out: While black surfaces such as traditional built-up asphalt shingle roofs can reach 185 degrees, a roof that’s white can be up to 70 degrees cooler because it bounces so much sunlight back into space.  

“The science of it is very basic,” says Hashem Akbari, a leader in the study of cool roofs and a professor at Concordia University in Montreal.

White roofs make sense particularly on commercial buildings because those buildings have their cooling systems on most of the year as computers and other machinery inside them create heat, says Chris Scruton, a project manager in the California Energy Commission’s research program in building energy efficiency.  With a white roof, “As much as 75 or even higher percent (of sunlight) can be reflected,” Scruton says.

Choose your hue
That’s great, you say, but what if you don’t want a white roof on your Colonial?

You’re in luck. There’s a roof for you, too.

Manufacturers can make colored cool roofs that stay much cooler than traditional colored roofs. They add pigments or glazing to roofing materials that reflect infrared light back into space. That unseen infrared light makes up 52% of light that falls to Earth; we can’t see it, but we feel it in the form of heat.

These cool roofs can take the form of tiles, shingles or metal. California’s MCA Clay Roof Tile, for instance, makes 33 cool roof tiles, with reflectiveness ranging from just over 30% (for many of the dark-hued tiles) to 76% (for “White Buff”), says Yoshi Suzuki, president and CEO. Traditional dark asphalt roofs only have about 5% to 15% reflectiveness.

Custom-Bilt Metals of Chino, Calif., Classic Metal Roofing Systems of Piqua, Ohio, and other metal roof manufacturers have added pigments to their line of painted metal roof products.

“People are starting to catch on” to the benefits, Suzuki says, but “it’s not so much residential yet.” In 2007, about one-quarter of the commercial roofing market consisted of Energy Star-rated (that is, highly efficient) roofing products, compared with about 10% of the residential market.

Source: www.MSN.com


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