Analytical Study of Residential Buildings With Reflective Roofs.
Analytical Study of Residential Buildings With
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.
1-800-553-6847 or 703-605-6000;
Order number: PB99-113136
roofs; ASHRAE; building technology; cooling; energy;
experimental design; heating; building loads; solar
reflectance; residential buildings; residential models;
TARP thermal resistance; ventilation; WYEC
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.