A build's cooling and heading cost can be effectively reduced by insulation under the roof surface. Adding increasing amounts of insulation is not always the best way to save energy. As part of total system design, a cool metal roof can be economical method for better energy efficiency.

Cool metal roofing is available unpainted, with oven-bake paint finishes, or with granular-coated surfaces. This family of roof can achieve solar reflectance of 70 percent. Reflected solar energy allows the roof surface to remain cooler, which means less heat is transferred into the building.

The infrared admittance of a roof is a measured of absorbed solar radiation that is reemitted from the roof surface to the sky. Admittance of metal roofing varies with the surface finish. Admittance of painted or granular-coated metal roofing can be as high as 90 percent.

Where annual cooling's loads dominate, a highly reflective and highly emissive painted or granular-coated metal roof is optimal for reducing energy consumption. Where annual heating loads dominate, an unpainted metal roof is more desirable because of its low infrared admittance.