A lot of factors go into making an energy efficient roofing system. The right amount of insulation helps keep the building cool in the summer and warm in the winter. A roof with high reflectivity makes the insulation more efficient. Johns Manville PVC roofing systems and modified bitumen roofing systems coated with TopGard 5000 are ENERGY STAR rated, listed with the Cool Roof Rating Council and are eligible to be incorporated into a LEED certified building. Below are links to external sites of interest about energy efficient systems.

Looking for Improved Performance in Roof Insulation?
Energy Star® Roofing Products
Cool Roof Rating Council
Leadership in Energy & Environmental Design (LEED)
Heat Island Group
California Building Energy Reference Tool