Cool systems for hot cities

On a hot summer day, Los Angeles, CA, like Baltimore, MD, Phoenix, AZ, Washington, D.C., and Tokyo, Japan, is c. 6-8 °F hotter than its surrounding areas. Dark buildings and pavement have replaced urban vegetation in these cities, absorbing more solar heat. The urban heat islands that are created result in increased air-conditioning costs, energy use, and pollution. Scientists at the Lawrence Berkeley National Laboratory have been studying the effects of roof system color and type on the energy used to cool a building. The results of this research indicate that roofing professionals should consider the reflectance (albedo) and emittance (release of absorbed heat) of the roof systems they install.