"Metal roofing is rapidly gaining acceptance as a very energy-efficient material. Property owners have reported energy savings of as high as 20% and even more after installing metal roofing. The reflectivity and subsequent energy efficiency of metal roofing has been confirmed in studies done by Florida Solar Energy Center, Florida Power and Light, Oak Ridge National Laboratory, and other independent organizations. Ongoing studies are conducted to continually substantiate and quantify the energy efficiency of metal roofing."
"Prepainted metal roofing can display solar reflectance of at least 65% and thermal emittance of 80%. This can have a tremendous impact on energy usage by reducing air conditioning costs and the smog and pollution that are created by the production of that energy. Additionally, the low thermal mass of metal roofing means that it dissipates heat very quickly once the sun goes behind a cloud or sets for the day. Other roofing materials have greater thermal mass and will continue to radiate captured heat into the structures beneath them even when the sun is not shining"
- Ecological Benefits of Metal Roofing, Metal Construction Association