Solar reflective coatings on metal roofing and siding can reduce surface temperature by 10 C to 15 C compared to conventional materials.
That temperature reduction outside on the wall and roof surfaces means lower temperatures inside barns, shops and houses, and that means lower energy costs, if heat is an issue.
Solar reflective coatings were developed in the United States to help the Green Building Council reduce energy costs in all types of buildings. The council determined that buildings consume 73 percent of electricity and are responsible for 38 percent of carbon dioxide emissions.
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Conventional materials used on roofs absorb 85 to 95 percent of solar heat energy. Cooler roof options, such as metal paneling sheathed in Valspar’s Fluropon SR coating, absorb less than 30 percent of solar heat energy.
This data prompted sheet metal companies to develop products that reduce those negative impacts on the environment. For sheet metal products, the development of solar reflective coatings has been a significant innovation. A solar reflective coating reflects harmful solar rays away from a building’s surface.
It requires no people or energy input to operate. The coatings reduce solar gain in winter as well, however there is less of that available at that time of year.
Jeff Alexander is vice-president at the Valspar Corp., one of the leaders in SR. He is in charge of sales in the coil and extrusion division.
“As the fierce rays of the sun reach the surface of a building’s roof and exterior, the absorbed infrared light is converted to heat, which steadily increases interior temperatures. If unchecked, this radically increases air conditioning use and overall electricity expenses,” says Alexander.
“In an effort to diminish this negative effect plus provide a wider range of sustainable building materials, coating manufacturers developed formulations that reflect infrared radiation. The result was solar-reflective pigments incorporated into exterior metal panel coatings. Roofs and siding that utilize these coatings stay much cooler than their non-reflective counterparts. They also provide an array of colour options that previously had absorbed considerably higher amounts of infrared light.”
Alexander says that metal paneling clad with a high-performance SR coating is now one of the leading construction practices employed to reduce overall energy consumption of a building. Valspar estimates that cool roofs have an average benefit of $20 to $30 savings per year per 1,000 sq. feet of roof surface.
Virtually every sheet metal manufacturer offers SR coatings. They are available in a range of coatings in polyvinylidene fluoride (PVDF), silicone-modified polyester (SMP) and polyester formulas.
