Long and Short Term Energy Savings of Cool Roofs
A building with a dark colored roof will consume more energy for air conditioning than a “cooler” building – a strain on both operating costs and the electric power grid. Cool roofs offer both immediate and long-term savings in building energy costs.
In a 2001 federal study, “Measured Energy Savings and Demand Reduction from a Reflective Roof Membrane on a Large Retail Store in Austin,” the Lawrence Berkeley National Laboratory (LBNL) measured and calculated the reduction in peak energy demand associated with the surface reflectivity of a vinyl roof on a retail building in Austin, Texas.
Instruments measured weather conditions on the roof, temperatures inside the building and throughout the roof layers, and air conditioning and total building power consumption. Measurements were taken with the original black rubber roofing membrane and then after replacement with a white vinyl roof with the same insulation and HVAC systems in place.
LBNL found that the average daily summertime temperature of the black roof surface was 168 F, but once retrofitted with a white reflective surface, it measured 125 F, a decrease of 43 F.
In conjunction with that, LBNL found that, compared to the original black membrane, the retrofitted vinyl membrane delivered an 11 percent decrease in aggregate air conditioning energy consumption, and a corresponding 14 percent drop in peak hour demand. Without considering any tax benefits or other utility charges, annual energy expenditures were reduced by $7,200 or $0.07/sq. ft.
Cool Roofing Codes, Programs & Standard
Additional Reading on Cool Roofing
- Sustainable Roofing: Presentation to the Cool Roof Rating Council by Target Corporation and Sika Sarnafil [1.49 MB]
- Trading Off Cool Roofs for Insulation [608 KB]
- Benefits of Cool Roofs on Commercial Buildings [1.65 MB]
- Do Cool Roofs Fit in Cool Climates?
- Measured Energy Savings and Demand Reduction from a Reflective Roof Membrane on a Large Retail Store in Austin [2.63 MB]
- Mitigating New York City's Heat Island with Urban Forestry, Living Roofs and Light Surfaces [1.82 MB]
- Vinyl Roofing as a Cool Roofing Solution [55 KB]
- Radiative Forcing and Temperature Response to Changes in Urban Albedos and Associated CO