September 2, 2014
Metal roofing material is known for its durability, but it also offers two other sustainable attributes that are sometimes overlooked: enhanced energy-efficiency and high recyclability.
When coated with a light-colored reflective paint, metal is a superior material for a cool roof. A three-year study on the energy efficiency and service life of metal roofs by Oak Ridge National Laboratory’s Buildings Technology Center found that the high solar reflectivity and emissivity levels of cool metal roofing can greatly mitigate urban heat island effects. The study used a solar spectrum reflectometer and an emission meter to test the efficacy of cool metal roofs.
Oak Ridge found that white coatings on other roofing materials displayed a 25% to 40% drop in their initial reflectance, but the metal roof tested retained 95% of its initial solar reflectance during the length of the study. Depending on the color of a painted metal roof, the reflectance ranges from 10% to 75%, which compares very favorably with the 5%-to-25%-range of an asphalt roof.
Metal is also highly reusable, and metal roofing material rarely ends up in landfills. Many metal roofs contain up to 40% recycled steels. Their material is also 100% recyclable. Research conducted by the Florida Department of Environmental Protection found that metal is one of the best eco-friendly roofing materials from a waste-reduction standpoint.
All in all, metal is among the most sustainable roofing materials, especially when you consider that metal roofs can last more than 60 years.