The roof is the element of the building envelope with the most direct and long-lasting exposure to sunlight. The color and reflectivity of the roof can have a significant effect on the thermal characteristics of the entire building. Facilities with a larger cooling than heating load profit from a light-colored, highly reflective surface that minimizes the heat gain in the summer. Buildings in northern latitudes do better with darker roofs, to attract and absorb light during the heating season. These same principles also apply to the outside wall coverings, although to a lesser extent.
Projects specifying siding or roofing materials to take advantage of the thermal properties of building materials such as siding or roofing can seldom be justified on the basis of energy savings alone. If the facility needs a new roof or a siding retrofit anyway, the energy savings from properly colored materials can justify their use over other more commonly used, less expensive materials. Of course, this also applies to new construction, when prudent decisions on roofing and siding can reduce energy costs for the life of the building.
In residential terminology, you need to use “cool” shingles ~ normal colors but which reflect much more sunlight. Dark, absorptive shingles are ideal for cold climates.
LOL. Whenever they have brownouts in California, where half the state has no electricity in the heat of the summer, I always think, “If they had a law requiring “cool” shingles on all California homes, they’d never again have power outages because of demand.” Before they came out with the special “cool” shingles, I used to think: If everybody in California (Arizona, Florida, New Mexico, Texas) painted their roof white…
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Excerpted from Going Green, available as an eBook at this list of eBook retailers online.