Cooling/Heating

Radiant barriers are thin metal films on a plastic or paper sheet to give them strength. They will reflect or stop approximately 95-97% of long-wave infrared heat radiation. Such barriers are usually stapled to the underside of attic rafters to lower summertime attic temperatures. Laying these barriers on the attic floor is also an option, but research indicates that the barriers' effectiveness is reduced by dust build-up. Lowering attic temperatures (which can easily reach 160°F on a sunny day) reduces heat penetration into the living space below and is frequently a cost-effective measure to lower air conditioning bills.

A study by the Florida Solar Energy Center found that properly installed radiant barriers reduced cooling loads by 7% to 21%. The study also found that temperatures of the roofing materials were only increased by 2°F to 10°F, which will have little or no impact on the life expectancy of a shingle. A radiant barrier will reduce, but not eliminate, high attic temperatures, but every little bit helps. The Florida study discovered that an attic radiant barrier can reduce air conditioning costs by at least 20%. The cost for radiant barrier material is very moderate at approximately 20 cents per square foot.

Aside from cooling, when placed underneath floors the radiant barrier can also reflect heat back into rooms. Since heat rises, by keeping floors warm we can save even more and use less energy to try to compensate for the inefficiency of our radiators.