Light Shingles Vs. Dark Shingles
Whether re-roofing or installing the first roof on a new home, one important consideration is color. Along with roof texture, roof color is a major aesthetic component of a building. However, for many consumers appearance may be trumped by energy conservation in these days of green construction.
National Geographic reports light-colored shingles reduce annual cooling costs by 10 percent to 20 percent in hot climates.
Impact of Location
A building's environment affects choices concerning initial construction or renovation. For example, in a residential neighborhood of Spanish-style homes with traditional, terra cotta clay roofs, it might adversely affect home value and neighborhood continuity to shingle with another material. Building owners may also be held back from choosing a light-colored roof due to historic preservation standards. Standards set by the National Register of Historic Places require replacement materials "match the historic material in design, color, texture and other visual qualities."
Asphalt shingles are usually the least expensive and prevalent roofing choice. They are also among the most heat absorbent, and their colors are primarily dark. This may be because of greater discoloration problems in light colors. The Environmental Energy Technologies Division of the University of California's Lawrence Berkeley National Laboratory says white asphalt shingles reflect just 30 percent of the solar heat that hits them. Their granular roughness probably "contributes to multiple scattering of light and thus to increased absorption."
Heat and Durability
Do light asphalt shingles last longer than dark ones? One residential roofing company based in Oregon says this may be the case if an attic is not properly insulated. An overheated attic, coupled with the higher surface temperature of a dark roof, may cause shingles to become prematurely brittle. Some homeowners have discovered they can decrease indoor temperatures and increase the life of an asphalt roof by coating it with white acrylic paint.
Dark roofs absorb more heat than light roofs. Progress Energy, a power company that serves the Carolinas and Florida, says research shows "roof color can impact home cooling costs significantly." The company says this is particularly the case when roofing combines light color and materials, such as tile, that are less heat absorbent than asphalt products. However, the company also recommends lowering indoor temperatures by installing sufficient attic insulation.
Lowering Indoor Temperature
The New York Times says studies "show that white roofs reduce air-conditioning costs by 20 percent or more in hot, sunny weather." The Times cited an example in Sacramento, Calif., in which the inside temperature of a house sometimes rose to 115 degrees Fahrenheit on summer days. By changing to a white roof, temperatures decreased to just 80 degrees when it was more than 100 degrees outdoors.
Construction industry sources note that in colder climates dark shingles may decrease energy used to heat a building during winter.