Energy saving properties of reflective roof coatings.
Recent testing of reflective roof coatings show that in all locations, reflective roofs reduced space cooling varying from 13% for new construction in St. Louis to 58% for existing residences in Los Angeles. Heating consumption was increased only slightly, from 3% in Miami to 6% in San Francisco. Still, the increase in heating was enough to increase combined heating and cooling costs in some colder places, such as Detroit and Seattle.
In the Sunbelt region (Los Angeles, Atlanta, Houston, Ft. Worth, Fresno, Miami and Phoenix) the annual energy savings from a new reflective roof in new construction was greater than adding another increment of R-11 ceiling insulation to current practice, and in all these places the combined heating and cooling costs were reduced.
The highest savings was in the hottest and sunniest location: Phoenix, Arizona.
Conclusions:
Except in northernmost locations and in cool, cloudy locations, the combined cost of heating and cooling is lower for houses with reflective roof surfaces than for houses with conventional roofs. While white roofing is effective at reducing cooling loads in all locations, it works best in hot sunny climates, in houses in which there is little or no attic insulation and where the ducts are located in the attic.
Homeowners in any location who wish to cut down on their cooling bills can adopt reflective roofing; for those in hot sunny climates, white roofs are highly recommended.
--Steven Konopacki
and Danny Parker
(Steven Konopacki is a principal research associate at Lawrence Berkeley National Laboratory. Danny Parker is a research scientist at the Florida Solar Energy Center.)
Related:
Reflective Roof Coating Test Results
Dark colors can also reduce heat!
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