Secondary Author(s)

Sonne, Jeffrey; Sherwin, John

Report Number




Buildings; Roofs


A series of tests were conducted in seven retail shops in a strip mall in Cocoa, Florida to examine how roof whitening would impact air conditioning load. The roof of the strip mall was conventional: unsurfaced galvanized corrugated metal with R-11 insulation suspended by purlins underneath. Below the insulation was the roof plenum which contained both the air handler and duct air distribution system. Cooling was accomplished in each shop by a dedicated direct expansion air conditioning (AC) system between 3 and 4 tons in size. Each had its air conditioning metered for half of the summer in a baseline condition. Building temperatures as well as meteorological conditions were also obtained on a 15-minute basis. The roof was then resurfaced white at mid-summer using a commercially available roof coating product. The measured roof surface reflectivity was altered from approximately 29% to 75%. The tests were phased over a two summer period so that the impact of surface degradation could be measured in the second year of exposure.(1)

The results for both phases of the project, showed a 25.3% average reduction (8.6 kWh) in summer space cooling energy (34.1 kWh/day to 25.5 kWh/day) in the seven shops with a range of savings of 13 - 48%. The percentage savings varied with the temperature maintained in the shops; those maintaining the lowest interior temperatures saved the least on a percentage basis, although the absolute space cooling energy reductions were more similar ranging from 6.4 to 13.4 kWh/day. Total annual air conditioning in the seven monitored shops averaged 6,780 kWh; estimated savings averaged 1,670 kWh. Impacts on space heating were not measured.

Date Published



Buildings - Roofs



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In Copyright