When the topic of energy conservation and efficiency turns to commercial roofing, roof color sparks as much discussion as roof structure and type of insulation. The use of black versus white roofing materials received much attention after a 2014 study conducted by The Heat Island Group at Berkeley Lab examined the surfaces – including roofs and paved areas – that contribute to the summer “urban heat island” effect that’s felt in many metropolitan areas.
The study revealed that choosing white roofing materials could result in an overall energy savings of 9-36%.1 Dark surfaces such as pavements and roofs absorb sunlight, which adds warmth to the air. In fact, darker surfaces contribute to creating urban air that’s 1-3°C (2-5°F) warmer than nearby rural air.1 In contrast, on a sunny summer day, a flat white roof can reflect up to 80% of the incoming sunlight and can reduce air conditioning costs by 10-15%, depending on the region.1
Where roof color is concerned, location also matters. Research published in the Proceedings of the National Academy of Science in 2014 found that the Mid-Atlantic and Midwest see the biggest overall summer temperature increases and that white roofs could offset the heat island-induced temperature increases.2 The study also concluded that if utilized across an entire metropolitan area, white roofs could reduce some, though not all, greenhouse gas-related warming. Benefits of cool roofs are particularly prominent for the urban areas stretching from Washington, D.C. to New York, Chicago and Detroit, and California’s Central Valley.
The trend toward changing roofing materials to promote energy efficiency and reduce the urban heat island effect has had an impact across the country, with many cities and virtually all 50 states mandating some type of cool roofing, often offering tax rebates or other incentives to promote the use of these materials. Over the past several years, New York and Philadelphia have launched white roof projects, and other major cities are expected to follow suit.
1White Roofs May Partially Offset Summer Warming by 2100, February 2014; climatecentral.org
Whether you’re in need of a new roof, maintenance or repair for an existing roof, contact Jottan for expert advice and service – (800) 364-4234.