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When the sun heats a roof, it’s primarily the sun’s radiant energy that makes the roof hot. Much of this heat travels by conduction through the roofing materials to the attic side of the roof. The hot roof material then radiates its gained heat energy onto the cooler attic surfaces, including the air ducts and the attic floor. A radiant barrier coating reduces the radiant heat transfer from the underside of the roof to the other surfaces in the attic.
Energy exchange is greatest when the temperature difference is high, when the emittance is high, and when the reflectivity is low. The underside of a roof deck made of wood will typically have a high emittance. When a radiant barrier with a much lower emittance covers that wooden surface, the thermal radiation is reduced.
Radiant barriers reduce energy losses from air conditioning duct work in the attic in three ways:
First, the outside surface of any duct work located in the attic exchanges thermal radiation energy with the roof deck in the same way as the attic floor. Because the temperature difference between the roof deck and the duct surface is even greater than that between the roof deck and attic floor, this thermal radiation is significant.
Second, the outside surface of the duct work exchanges energy with the air in the attic space, and that energy loss is reduced when the attic temperature is moderated by the radiant barrier.
Third, ducts leak. When return ducts leak, the air that is sucked into the ducts through the leaks feeds into your HVAC air handler, which then has to use extra energy to cool this warmer air. When the capacity of the HVAC system is nearing its limit, as on very hot summer days, this can make a noticeable difference in the comfort within the house.
Radiant barrier installation takes only a few hours, and the spray provides an even coating across all the contours of an attic. Let Green Collar be your Austin and Central Texas radiant barrier contractor. We have on site technicians that are Building Performance Institute (BPI) certified professionals and can properly identify any major issues.
Contact us to schedule a free home energy audit to see if installing a radiant barrier is the right option for your home and make your home energy efficient to save you money.
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