On a hot summer day in the United States, a traditional roof can get as hot as 185 degrees! Hot roofs contribute to the urban heat island effect, where temperatures in cities are warmer that surrounding natural areas. One way to reduce the urban heat island effect in cities is to install cool roofs, using materials that reflect heat and stay cooler than traditional roofs. For comparison, a black roof can reach over 180 degrees and a metal roof can reach 160 degrees on a hot sunny day, whereas a cool roof will only reach a peak temperature of about 120 degrees. And, because a cool roof transfers less heat to the building below, it can help save on air conditioning energy costs for a home or building.
If you are replacing a roof or building a home, consider using cool roofing materials. Cool roofing can be used on any building, but is especially useful when:
- The weather is 80 degrees or hotter with clear skies for at least three months each year;
- You use significant energy for cooling at least three months out of the year;
- Your home or building duct system is in the attic;
- The roof accounts for at least one-fourth of the building's exterior surface;
- You notice that your roof materials crack or age prematurely from sun damage.
Learn more about Cool Roofs from the U.S. Environmental Protection Agency at www.epa.gov/heatisland/mitigation/coolroofs.htm.
(Source: U.S. Environmental Protection Agency. "Cool Roofs," in Reducing Urban Heat Islands: Compendium of Strategies. Available from www.epa.gov/heatisland)
