Asphaltic steep-slope roofs with solar reflectance provide energy efficiency and sustainability
A combination of proven durability, pleasing aesthetics and reasonable cost make asphalt shingles the predominant steep-slope roof covering selected by building and home owners alike.
The dominance of asphalt shingles is also prevalent in the cool roof arena through the development and marketing of highly reflective asphalt shingles. These products maintain a varied color palette that allows customers to match shingles to the design and color scheme of their home while offering the benefits associated with high solar reflectance.
The Cool Roof Rating Council defines a cool roof as one that uses products with high-solar reflectance, the ability to re-radiate absorbed energy, high thermal emittance, and the ability to reflect the near-infrared wavelengths of the sun’s energy. Asphalt shingles are achieving high marks in all of these metrics through the incorporation of more lightly colored, highly-reflective granules.
Solar reflectance values for conventional asphalt shingles range from 0.04 for black to about 0.25 for a white shingle. The use of granules made with special pigments that reflect most of the near-infrared portion of the solar spectrum has allowed the development of aesthetically pleasing colors with solar reflectance values that extend to 0.40, giving the consumer more design flexibility when selecting a roofing system.
It is important to note that the mineral granules used on highly reflective shingles are essentially identical to those used on asphalt shingle roofs for decades, except for the development of near-infrared reflective pigments. In addition, both conventional and highly reflective asphalt shingles maintain thermal emittance values that often exceed 0.80.
Reed Hitchcock, Executive Vice President of the Asphalt Roofing Manufacturers Association (ARMA), said more and more manufacturers are now producing and marketing ‘cool’ steep slope products.
“Raising awareness of cool rated shingles is crucial as energy requirements become more stringent on both commercial and residential buildings,” said Hitchcock. “Asphalt shingles, both cool and conventional, continue to be the most cost effective products on the market and consumers need to be aware of this.”
Although highly reflective and highly emissive products are an increasingly popular roof option, they represent only one of many approaches to help building owners and consumers reduce building energy use and address contemporary environmental concerns. For the best results, ARMA recommends a “whole building approach” for energy conservation, mitigation of urban heat islands and improved air quality.
To learn more about cool roofing, please visit www.asphaltroofing.org.
The Asphalt Roofing Manufacturers Association (ARMA) is the North American trade association representing the manufacturers and suppliers of bituminous-based residential and commercial fiberglass roofing products, roll roofing, built-up (BUR) roofing systems and modified bitumen roofing systems.