Another way to keep your house cooler – and reduce urban heat island – is to install a “cool roof” that reflects sunlight, lowers the roof’s temperature, and reduces heat flow into the house. Ideally a cool roof is installed during new construction or routine repair. Existing roofs can also be retrofitted with cooling, solar-reflective coatings.
In general, cool roofs are lighter colors (white, beige, silver, sky blue, and muted green) that, by reflecting sunlight, can lower roof temperature as much as 50 degrees compared to a dark grey roof on hot, sunny days. Dark-colored roofs might be slightly preferable in the winter, but the energy savings from light roofs in the summer outweigh winter energy savings. The photo above was shot recently while flying over Dallas/Fort Worth, an area known for long, hot summers.
Roofing materials also affect sunlight reflection. Both metal roofs and light-colored clay or concrete tiles work well. Asphalt shingles, the most common type of roofing material, are ordinarily one of the most non-reflective and heat-absorbent options. However, manufacturers are now making new lines of asphalt shingles with solar-reflecting granules.
If changing a dark-colored roof isn’t in the picture, considerable energy can be saved by adding a solar-reflecting coating, and insulating and ventilating the attic. For in-depth information on all these topics, see the Department of Energy’s Energy Saver article,Cool Roofs.
Read the entire Good Energy Newsletter, Spring 2023