Radiant Barriers offer a real energy savings when installed properly, but not the 20-50% you can often see advertised. If you want to know the technical details of how a radiant barrier works, you can find them in an article by Phillip Fairey. According to Ingrid Melody on the Florida Solar Energy Center (FSEC) site, you can expect to save 8-12% of your annual cooling costs in the southeast. This is based on a comprehensive field monitoring study conducted for Florida Power Corporation (FPC) by FSEC on the performance of attic radiant barrier systems in central Florida homes. In the Atlanta area, you can expect to save less in total dollars, as we have a shorter cooling season. According to the National Climatic Data Center, Florida has significant cooling from April through November, while Georgia has its most significant cooling in June through August.
Where do they come up with 40%? Well, a radiant barrier can reduce the heat gain through your ceiling by 40%. However, the heat gain through your ceiling is only about 20% of your cooling load. So your real savings is about 40% of 20% or about 8-12% of your cooling load.
While you will not get a 20-50% reduction, you can get an 8-12% reduction. As with any modifications made to your home, you should view your home as a system. Changes made for one purpose can have more than the proposed affect on your home. This is the case with radiant barriers. First, this is not the most cost effective modification you can make to your home unless you have already accomplished other energy saving measures. In the vast majority of houses built before 2009, air sealing your attic and adding additional insulation followed by doing the same to your crawl space (see crawlspace insulation) will give you the most cost effective improvements. To know where to spend your money and get the most bang for your buck, get a comprehensive energy assessment. Second, adding a radiant barrier without air sealing the attic floor has a probability of causing condensation on the radiant barrier. In the winter, moist air from the living areas of your home can infiltrate into the attic and condense on the cold surface of the radiant barrier. This moisture can drip into the blown insulation on the attic floor and onto the ceiling joists causing mildew, mold, and rot.
Installation of radiant barriers has a relatively low cost, but varies based on attic configuration. So, if you live in the southeast, have already accomplished the more cost effective energy savings improvements, and your HVAC ducts are in the attic, maybe you want a radiant barrier. If you want to install a radiant barrier, you can contact us using the I Want A Radiant Barrier page.
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