Replacing a "hot roof" on a commercial building or residence is getting to be one of the coolest ways to reduce the summer's sky-high electric bills.
Cool roofs reflect sunlight and heat away from a building and reduce roof temperatures up to 50 to 60 degrees compared with conventional materials, reducing the "heat island" effect, according to research by the Lawrence Berkeley National Laboratory.
"Coolness" is measured by solar reflectance and thermal emittance.
The Cool Roof Rating Council, or CRRC, a nonprofit roof-rating service, defines solar reflectance as "the fraction of solar energy that is reflected by the roof," with thermal emittance defined as "the relative ability of the roof surface to radiate absorbed heat."
But put more simply " it minimizes the heat transfer to the building below.
And the best news is that the new cool roofs, or "white" roofs, are no more expensive than "hot" roofs, said an Oklahoma City-roofer, who specializes in the new roofs.
"Price-wise, it's right there with the old systems," said Lance Cornman, owner of Mid-America Roofing and Construction. "You can have a LEED-certified roof for about the same price."
Nationally, 25 percent of commercial roofing products and 10 percent of residential roof products are "cool."
Cornman said most of the commercial roofing installations his company is handling now on flat roofs use a white membrane instead of the more traditional asphalt roof. It's been a tougher sell in the residential market, where roofs tend to have a greater slope.
"People in general are not proactive in energy conservation yet," he said of Oklahomans in general. "But there's nothing ecologically friendly about a shingle."
Part of the problem is aesthetic, with homeowners preferring the look of dark roofs over light or white roofs. Most homes in Oklahoma also do not have flat roofs, which account for many of the cool roof applications.
That's being solved as more and more cool roof Energy Star products come on the market.
"Most of the applications are commercial applications and not residential," Cornman said.
Whether commercial or residential, the roofs result in other benefits, including reduced energy use, reduced air pollution and greenhouse gas emissions and improved human health and comfort.
Reflective asphalt shingles and Energy Star-qualified metal roofs installed on existing homes are eligible for federal tax credits.
Tax credits of up to 30 percent of cost (up to $1,500) are available for the roofs, excepting new construction and rental properties.
More information on products that qualify for the credits is online at www.energystar.gov.
"The owners have to weigh the costs against the energy savings," Cornman said.
photo, from left Gertrudis Garcia, Miguel Angel Balderas and Ricardo Salinas of Mid-America Roofing and Construction weld white reflective roofing material pieces together on the expansive roof of a new Crest Foods under construction at S.W. 104th and May Avenue. photo/Mark Hancock