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Abstract
Determining how weathering affects the reflectance and emittance of metal roofs is of paramount importance for accelerating the market penetration of metal roofign in both residential and commercial applications. Ultravioulet radiation, atmospherical pollution, microscopic growths, acid rain, temperature cycling caused by sunlight and sudden thunderstorms, moisture penetration, condensation, wind, hail, and freezing and thawing all contirubute to the weathering of a roof's exterior surface. However, data describing the impact of weathering are extremely sparse simply because of the time and patience required to collect and interpret the data. Temperatur, heat flow, refluctance, and emittance field data have been electronically cataloged for a full two years for 12 different painted and unpainted metal roofs exposed to weathering on an outdoor test facility. A white-painted metal surface having a moderate reflectance and high emittance, showed the best thermal performance for predominantely cooling-load climates. For predominantly heating-load climates, a painted metal surface having moderate relfectance and low emittance showed excelelnt balance for reducing heat gain in the summer and heat loss in the winter.
Determining how weathering affects the reflectance and emittance of metal roofs is of paramount importance for accelerating the market penetration of metal roofign in both residential and commercial applications. Ultravioulet radiation, atmospherical pollution, microscopic growths, acid rain, temperature cycling caused by sunlight and sudden thunderstorms, moisture penetration, condensation, wind, hail, and freezing and thawing all contirubute to the weathering of a roof's exterior surface. However, data describing the impact of weathering are extremely sparse simply because of the time and patience required to collect and interpret the data. Temperatur, heat flow, refluctance, and emittance field data have been electronically cataloged for a full two years for 12 different painted and unpainted metal roofs exposed to weathering on an outdoor test facility. A white-painted metal surface having a moderate reflectance and high emittance, showed the best thermal performance for predominantely cooling-load climates. For predominantly heating-load climates, a painted metal surface having moderate relfectance and low emittance showed excelelnt balance for reducing heat gain in the summer and heat loss in the winter.
Date
12/2001
12/2001
Author(s)
Scott Kriner; William Miller; Andre Desjarlais
Scott Kriner; William Miller; Andre Desjarlais
Page(s)
Keyword(s)
thermal performance; standing seam metal; weathering; reflectance; metal roofing; heat gain; heat loss
thermal performance; standing seam metal; weathering; reflectance; metal roofing; heat gain; heat loss