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Cool It, Roof

  Cool It, Roof

If your roof is in need of repair or replacement, or if you’re building a new house, consider whether investing in a cool roof makes sense for you. For those homeowners with conventional roofs that are in good shape, there are still ways to retrofit a roof to make it cool that may reduce energy use and increase your home’s comfort.

What Is a Cool Roof?

No, it doesn’t wear sunglasses and a leather jacket. A cool roof strongly reflects sunlight and cools itself by efficiently emitting solar radiation to its surroundings, which can lower the roof temperature by up to 50 degrees. When the roof stays cooler, it conducts less heat to the building below.

The two primary characteristics that determine a roof’s cool factor are solar reflectance and thermal emittance. Both properties are measured on a scale of 0–1, where 1 is the most reflective or emissive. The Cool Roof Rating Council records these measurements for a product’s initial values and after three years of exposure to the elements. CRRC publishes the results online in their Rated Products Directory, which is available to the public at no charge. This consumer resource allows comparison of rated values across various product types and brands.

A cool roof can provide these benefits:

  • Reduce utility bills associated with air conditioning by 7 to 15 percent.
  • Increase your home’s comfort.
  • Prolong the life of your heating, ventilation and air conditioning system.
  • Extend roof life, reduce roof maintenance costs and avoid repeated re-roofing.
  • Decrease peak electricity demand, which can help prevent power outages.

How To Make the Switch

There are a range of options for upgrading your roof to cool status, from coatings featuring special pigments and asphalt shingles with coated granules that provide enhanced solar reflectance to metal roofs and even “green” roofs, for the rooftop garden inclined. The best option for your home will depend on a number of factors, including how steeply your roof is sloped and your area’s climate, particularly its humidity level. For more information, visit energy.gov or coolroofs.org.