Cool roofs save energy
- Lawrence Berkeley National Lab., CA (United States)
Dark roofs are heated by the summer sun and, thus, raise the summertime cooling demand of buildings. For highly absorptive roofs, the difference between the surface and ambient air temperatures may be as high as 50 C (90 F), while for highly reflective roofs with similar insulative properties, the difference is only about 10 C. For this reason, cool roofs are effective in reducing cooling energy use. Typically, cool roofs incur no additional cost if changes are incorporated into routine reroofing schedules. Several experiments on individual buildings in California and Florida show that painting roofs white reduces the air-conditioning load between 10% and 50% (corresponding to savings ranging from $10 to $100 per year per 100 m{sup 2}), depending on the thickness of insulation under the roof. The savings, of course, are strong functions of the thermal integrity of a building and climatic conditions. This paper focuses on field data documenting the impact of cool roofs in reducing cooling energy use in several residential and commercial buildings in northern California and in Florida. Simulated savings for several US metropolitan areas are also presented. Finally, policy and implementation issues such as ratings and ASHRAE standards are briefly discussed.
- Sponsoring Organization:
- USDOE Assistant Secretary for Energy Efficiency and Renewable Energy, Washington, DC (United States)
- DOE Contract Number:
- AC03-76SF00098
- OSTI ID:
- 649412
- Report Number(s):
- CONF-980123--
- Country of Publication:
- United States
- Language:
- English
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