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Analytical Study of Residential Buildings With Reflective Roofs.


pdf icon Analytical Study of Residential Buildings With Reflective Roofs. (5613 K)
Zarr, R. R.

NISTIR 6228; 80 p. October 1998.

Available from:

National Technical Information Service (NTIS), Technology Administration, U.S. Department of Commerce, Springfield, VA 22161.
Telephone: 1-800-553-6847 or 703-605-6000;
Fax: 703-605-6900.
Website: http://www.ntis.gov
Order number: PB99-113136

Keywords:

roofs; ASHRAE; building technology; cooling; energy; experimental design; heating; building loads; solar reflectance; residential buildings; residential models; TARP thermal resistance; ventilation; WYEC

Abstract:

This report presents an analysis of the effect of roof solar relfectance on the annual heating (cooling) loads, peak heating (cooling) loads, and roof temperatures of residential buildings. The annual heating (cooling) loads, peak heating (cooling) loads, and exterior roof temperatures for a small compact ranch house are computed using the Thermal Analysis Research Program (TARP). The thermal performance requirements for the thermal envelope of the residence are based on prescriptive criteria given in the American Society of Heating, Refrigerating, and Air-Conditioning Engineers, Inc. (ASHRAE) Standard 90.2-1993. The residential models, with minor modifications in the thermal envelope for different locations, are subjected to hourly weather data for one year compiled in the Weather Year for Energy Calculations (WYEC) for in the following locations: Birmingham, Alabama; Bismark, North Dakota; Miami, Florida; Phoenix, Arizona; Portland, Maine; and, Washington, DC. Building loads have been determined for a full factorial experimental design that varies the following parameters of the residential model: solar reflectance of the roof, ceiling thermal resistance, attic ventilation, and attic mass framing area. Included in this report is a simple economic analysis that examines cost savings for each geographic location. The estimated annual energy costs for electric and gas heating are plotted versus roof solar reflectance for different levels of ceiling thermal resistance. For a residence without attic insulation in a hot climate, substantial savings are available by making the roof more relective. At higher levels of ceiling thermal resistance, the savings are less.