A series of field experiments in Florida have examined the impact of reflective roof coatings on air conditioning energy use in occupied homes. The tests were conducted on nine residential buildings from 1991 to 1994 using a before and after protocol where the roofs were whitened at mid-summer. Measured AC electrical savings in the buildings during similar pre- and post-retrofit periods averaged 19%, ranging from a low of 2% to a high of 43%. Utility peak coincident peak savings averaged 22%. Cooling energy reductions appear to depend on ceiling insulation level and roof solar reflectance, air duct system location and air conditioner sizing relative to load.

A complementary thermal study of the effect of reflective roofing systems has been conducted in a side-by-side roof test facility. Ceiling heat flux reductions up to (60%) were measured from reflective roofing in these experiments. However, the test results have also shown degradation in solar reflectance and associated thermal performance after a year of exposure.

David Beal (Florida Solar Energy Center)

Parker, D., Barkaszi, S., Chandra, S., Beal, D., “Measured Cooling Energy Savings From Reflective Roofing Systems In Florida: Field And Laboratory Research Results,” Funded by the Florida Energy Office in support of the Building Design Assistance Center.