Have energy savings been measured?1
Extensive experimental work has identified the energy savings and peak-load reduction benefits of radiant barriers in attics in the southern climates of the U.S. Eight homes, all with air-handling equipment located in the attic, were retrofit with radiant barrier systems in 2000 in central Florida. Subsequent monitoring and data analysis showed cooling energy savings of 9%, peak load reduction of 16%, and an improvement in indoor comfort.i
Photos from "Parker, Sherwin, and Anello, 2001" , used by permission from
Florida Solar Energy Center, 2001
Previous experimental work in Tennessee on uninhabited homes with no ductwork in the attic also showed significant cooling energy savings.ii Significant savings due to radiant barriers were also measured in controlled laboratory experiments, with and without duct systems in the attic.iii Numerous other studies have established the energy conservation characteristics of a radiant barrier system, with and without the impact of ducts.iv,v,vi,vii,viii As expected, these sutdies point out the importance of multiple factors in determining the potential energy savings, most importantly: the climate, the presence or absence of ductwork in the attic, and the amount of insulation on the floor of the attic.
Photos from "Miller et al., 2010", showing temperature and heat flux monitor locations in test houses at For Irwin, California, 2010
Most of the field tests have been done with clean radiant barriers. Laboratory measurements have shown that dust on the surface of aluminum foil increases the emittance and decreases the reflectivity. This means that dust or other particles on the exposed surface of a radiant barrier will reduce its effectiveness. Radiant barriers installed in locations that collect dust or other surface contaminants will have a decreasing benefit to the homeowner over time. When radiant barriers are newly installed and clean, some testing shows that the attic floor application will work better than the roof applications.
1This material is excerpted from a paper presented at the Building Envelope Conference in 2010. (Stovall et al, 2010)