White roofs and other cool roofing materials help reflect the sun, which offers numerous benefits. Not only does it keep the building cooler for occupants and help reduce energy costs, but also it minimizes the "heat island" effect associated with traditional black roofs. In California, residential and commercial buildings that have cool, reflective roofs may receive energy credits for meeting the state's Title 24 Energy Efficiency requirements. While most TPO roofs are white and highly reflective, the majority of EPDM roofs are black, according to Buildings.com. To comply with Title 24, EPDM roofs require a special white coating to enhance reflectivity.
Source : http://homeguides.sfgate.com/comparing-thermoplastic-polyolefin-roofing-epdm-74959.html