Reflective Roof Coatings: An Energy Saver that Hides in Plain Sight
Earlier this month, The Roof Coatings Manufacturers Association released the Reflective Roofs Rebates Database to the general public. The database, which offers information on rebates, loans, grants and tax credits, previously was available only to association members.
Reflective roof coatings is one of those typically unsexy good ideas that hide in plain sight. Simply, covering the roof of a building with the right coating can cause energy to bounce off, instead of be absorbed by, the roof. This can save money – big money because the energy that is absorbed into the roof heats the interior and must be cooled. This means that air conditioners must work harder and consume more electricity.
Laura Dwulet, the General Manager of the Roof Coatings Manufacturers Association (RCMA), told Energy Manager Today that both visible and ultraviolet radiation are reflected by these coatings. The amount of savings can be significant, but varies according to location, the roof’s insulation and the cost of electricity.
Estimates of the savings are available. Dwulet wrote that the Lawrence Berkeley National Laboratory, Oak Ridge National Laboratory and the National Roofing Contractors Association, and several roofing material manufacturers have computer programs that can estimate the savings. Roof material manufacturers also have simulation programs, and there are consultants available with regulatory knowledge. Living Green posted a story with estimates of the savings from use of reflective roofs are available from Lawrence Berkeley, The California Energy Commission and the National Center for Atmospheric Research. It’s unlikely the estimates – which all are impressive – have changed much since the story was posted in July 2014.
One indication of the potential energy savings was offered by the University of Queensland in Australia. According to Architecture & Design, the school commissioned a two-year study in houses, schools, offices and retail spaces in Townsville and Brisbane. The study found that that white roofs reflected 88 percent of the sun’s energy. A colored roof reflected less than 65 percent and a dark roof less than a quarter. The white roof reduced interior temperatures 2 degrees Celsius in interior spaces that were not air conditioned. Energy saves were between five percent and 30 percent. In Springfield, an electricity use in a block of classrooms was reduced 1,144 kWh annually, the story said.
Dwulet told Energy Manager Today that the life of a roof can be extended by as much as 10 years is a reflective coating is applied. These coatings, Dwulet said, usually are made of acrylics, urethanes, styrene-butadiene-styrene (SBS), styrene-ethylene butadiene-styrene (SEBS) and other substances.
Almost any type roof of any age can get this treatment, she wrote. “A reflective roof is defined by ENERGY STAR as one that has properties of at least 65% reflectivity and 50% emissivity after 3-year aging. It reflects solar energy back into space so the roof surface remains cooler.”
There seems to be very little downside to reflective roof coatings. Dwulet said that metal, spray polyurethane, single-ply modified bitumen, built-up roof systems and others are candidates for this approach. Ballasted and gravel surfaced membranes are not, however.
There even are tax breaks. Dwulet said that there are financial breaks. “Coatings are considered ‘restoration’ and not a new roof system installation,” Dwulet wrote. “Therefore they may usually be expensed in the fiscal year during which they are applied instead of amortizing the cost over the life of the roof (as in a new membrane installation). This can be a huge tax benefit to some building owners.”
It is not surprising that roofs are a major source of energy efficiency. Earlier this month, Energy Manager Today posted a blog about the growth of roofs that are made more efficient by hosting trees and vegetation. The use of these coatings on asphalt shingles – which, of course, are more common for residential use – is a “very controversial” subject, according to House Energy.
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