Preliminary survey of the solar reflectance of cool roofing materials

Air-conditioning energy savings and improved comfort in hot climates can be obtained with the use of roofing materials that reflect solar radiation. Available quantitative information on the solar reflectance of most roofing materials is insufficient, so it is difficult for building designers to choose cool materials. Here we report quantitative values of solar reflectance for a few types of materials and discuss which material properties, such as composition, roughness, purity, etc., affect the solar reflectance. Outdoor temperature measurements on materials in sunlight are used to illustrate the strong correlation of roof temperature with solar absorptance, and further, to demonstrate the effects of infrared emittance and convection.