A Cool Roof is more than just a roof painted white. To be a Cool Roof, a roof must be treated with a specialized coating material that is lightly colored and has two unique properties: high solar reflectivity and high infrared emissivity.
Solar reflectivity expresses the degree to which a roof reflects the visible, infrared and ultraviolet rays that comprise solar energy. Surfaces with high solar reflectivity reflect more infrared and ultraviolet rays.
Infrared emissivity refers to the roof's ability to give off its absorbed heat. Highly emissive surfaces are cooler than non-emissive surfaces since they have the ability to shed more absorbed heat at a faster rate.
A Cool Roof reduces the amount of energy absorbed by the roof which helps lower a building's temperature and cuts energy costs.