Products for Steep Roofs (Pitch > 2:12)Īsphalt shingles are composed of a fiberglass web coated with filled asphalt, or filled modified asphalt, which has been surfaced with colored ceramic-coated rock. Such “cool colored” products typically reflect about 30 – 60% of sunlight, staying cooler than conventionally colored products (though not as cool as white).
However, since about half of sunlight arrives as invisible “near infrared” radiation, we can boost the solar reflectance of dark materials by using special pigments (colorants) that preferentially reflect this invisible light. White roofing products stay coolest in the sun, reflecting about 60 – 90% of sunlight. Certain types of roofing products can also be retrofitted with cool coatings, but this will incur extra material and labor costs. The easiest and least expensive way to make your roof cool is to choose a cool covering during new construction, or when your existing roofing covering needs to be replaced. Paths to a Cool RoofĬool roofing products usually cost no more than comparable conventional roofing products. There are cool options for nearly all types of roof coverings. There are many types of roof systems available, but the surface solar reflectance of the roofing product-the outermost layer of the roof exposed to the sun is, also known as the roof covering-determines whether the roof is cool or not. Help offset global warming by reflecting more sunlight to outer space.Decrease power plant emissions by reducing the demand for energy to cool buildings.Reduce peak electricity demand, which can help prevent power outages.Slow the formation of smog from air pollutants, which are temperature-dependent, by cooling the outside air.Lower local outside air temperatures, thereby lessening the urban heat island effect.That is, absorbing less sunlight at the roof reduces heat conduction into the building, increasing the need for mechanical heating in winter. Beyond the building itself, cool roofs can also benefit the environment, especially when many buildings in a community have them. Decreasing roof temperature, which may extend roof service lifeĬool roofs can also incur a winter heating penalty.Improving indoor comfort and safety for spaces that are not air conditioned.Making it possible to downsize new or replacement air conditioning equipment, saving money and potentially increasing cooling efficiency.Qualifying for money-saving rebates from utilities or government programs.Helping older inefficient (or undersized) air conditioners provide enough cooling for today’s hotter summers.Reducing energy bills by decreasing air conditioning needs.
A cool roof can benefit a building and its occupants by:
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