The term cool roof refers to a roofing product with high solar reflectance (SR) and thermal emittance (TE) properties. These properties help reduce electricity used for air conditioning by lowering roof temperatures on hot, sunny days. Solar reflectance refers to a material’s ability to reflect the sun’s solar energy back into the atmosphere. Thermal emittance provides a means of quantifying how much of the absorbed heat is rejected for a given material. Both properties are measured from 0 to 1 and the higher the value, the ‘cooler’ the roof.