Research Shows the Benefits of Cool Roofs for Building Energy Savings

By Greg Zimmerman, Executive Editor

On July 19, 2010, Secretary of Energy Steven Chu announced that cool roofs would be mandatory on all Department of Energy (DOE) facilities. He also urged other federal agencies to follow suit. Chu, who is also a Nobel-prize winning scientist, cited a possible 10 to 15 percent reduction in building energy use, depending on the configuration of the building and other variables, “simply by having a white roof.”

But energy savings isn't the end of the potential benefit of cool roofs. Two further reasons Chu mentioned for his advocacy of cool roofs are the role they can play in helping to mitigate global warming and their ability to reduce urban heat islands — whereby dark roofs and asphalt pavements in concentrated urban areas increase the air's ambient temperature between 6 and 8 degrees compared to suburban or rural areas. From 50 to 65 percent of urban surfaces are covered with roofs or pavement, and Chu cited a Lawrence Berkeley National Laboratory (LBNL) study that says increasing the reflectance of those surfaces would have the same effect in terms of global warming mitigation as removing every car in the world from the road for 11 years.

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