A basic, unpainted metal roof will reflect a large percentage of the solar radiation usually absorbed in your attic and home by an asphalt roof. A structure with a pre-painted or granular coated metal roofing systems not only reflect solar energy but also cools by re-emitting most of what solar radiation is absorbed.
White-painted metal roofing has the highest solar reflectance value of any roofing product available and can save you up to 40% of your annual energy bills.
An added benefit is that most metal roofing, including standing seam, can be installed directly onto an existing asphalt roof, promoting quick installation as well as decades of environmentally-sound, maintenance-free strength and beauty.
This information is from the Metal Roofing Alliance.To find out more information, click on the link above.