High solar reflectance and high infrared emittance roofs incur surface temperatures that are only about 3°C (5°F) warmer than the ambient air temperature, while a dark absorptive roof exceeds the ambient air temperature upwards of 40°C (75°F).
In predominantly warm climates, the high solar reflectance and high infrared emittance roof drops the building’s air conditioning load and reduces peak energy demands on the utility. In North American climates, being predominantly cold, a more moderate reflectance and a low emittance result in a warmer exterior roof temperature, which reduces heat loss from the building.
Temperature, heat flow, reflectance, and emittance field data have been catalogued for a full 3 years for 12 different painted and unpainted metal roofs exposed to weathering on an outdoor test facility. Habitat homes were tested unoccupied for a full summer in Ft. Myers, Florida.
Measurements showed that the white reflective roofs reduced cooling energy consumption by 18-26% and peak demand by 28-35%. The houses were side-by-side, and had different roofing systems designed to reduce the
attic heat gain.
Results show that a judicious selection of the roof surface properties of reflectance and emittance represent the most significant energy and cost saving options available to homeowners and builders.
Metal roofing is a proven product, more durable than most available roofing systems. Metal roofs simply last longer, and is often the roofing choice for many government, school and industrial buildings.
Metal roofs rate high in wind, fire, and hail resistance.
Not only will a metal roof keep your house comfortable, regardless of the weather outside, it may actually lower your air conditioning and heating bills.
According to the National Association of Homebuilders Research Center, 20 billion pounds of asphalt shingles are dumped into US landfills every year. The recycled content of the steel in a metal roof is far superior to asphalt. Metal roofs also have a low per unit area weight, making it possible in most cases to install directly over existing roofs, saving removal and disposal costs.