Painted metal roofs retain 95% of their initial reflectance and emittance over time.Ĭool Metal Roofing typically has a minimum recycled content of 25% and is 100% recyclable at the end of a long, useful life. Finally, unlike many roofing materials, metal's low thermal mass will not store heat and thus radiate it into a building in the evening hours.
METAL ROOFS FOR HOMES CODE
Such pre-painted metal roofing products meet the reflectance requirements of all major energy code initiatives. Emissivity as high as 90% can be achieved for painted and granular-coated roofing. Metal roofs with oven-cured, pre-painted organic coatings that incorporate new "cool pigment" technology offer high total solar reflectance and high infrared emittance even with darker colors. Mill-finish metal roof systems have very high solar reflectance, providing further reductions in heat gain. Many products are also formed in ways that stop heat transfer through conduction by allowing only minimal contact between the metal and the underlying structure. Many metal roof systems are reflective, easily vented, and lend themselves well to insulated roof systems to help reduce heat gain into a building. With proper design, cool metal roofing systems save energy by reducing a building's cooling and/or heating load. Cool metal roofing products are part of an interdependent system of exterior roofing surfaces, substrates, underlayments, configurations, ventilation, and insulation.
It is available in a wide variety of finishes, colors, textures, and profiles, for steep-slope and low-slope applications. What is Cool Metal Roofing?Ĭool metal roofing is a family of sustainable, energy efficient roofing products comprised of unpainted metal, prepainted metal, and granular-coated metal. See WBDG Evaluating and Selecting Green Products for more information. Additionally, many of the metals used in roofing will have recycled content varying from 25% to 95%, often with much of that recycled content being in the post-consumer and pre-consumer categories.
With its expected long life, metal roofing is a highly desirable and sustainable building component. The metallic coatings include zinc (galvanized), 55% aluminum-zinc alloy (Galvalume® sheet), 5% aluminum-zinc alloy (Galfan®), aluminum and lead-tin alloy (terne). The predominant metal roofing substrate is metallic-coated steel sheet. Metal roofing products are available in a range of metals including steel, aluminum, copper, zinc, stainless steel, and titanium. Metal roofing is represented by a variety of metal-based roof coverings designed to provide buildings with protection from the elements allow for positive drainage of water from the roof surface and to keep contents and occupants dry and comfortable. Cool metal roofing is also eligible for other cool roof rating programs such as the Cool Roof Rating Council. Cool metal roofing easily meets the requirements of the EPA's Energy Star® program. Cool metal roofing can also provide the desired high reflectance and high emittance where cooling loads dominate. Cool metal roofing can provide the desired high reflectance and low emittance in climates where heating loads prevail. In fact, the solar reflectance and infrared emittance of a metal roof can be engineered to meet the climate requirements of the building. Though diverse in appearance, metal roofing has many common attributes such as durability, recycled content, recyclability, fire resistance, low weight, and low life-cycle cost.ĭepending upon the surface finish, cool metal roofing can provide enhanced energy efficiency with its solar reflectance and infrared emittance properties. Metal roofing is available in a wide variety of substrates, colors, textures, and profiles. Metal roofing has been available and utilized as a roofing material for centuries.