Solar Reflectance and Thermal Emittance
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چکیده
The solar reflectance and the thermal emittance of a roof surface are important surface properties affecting the roof temperature, which, in turn, drives the heat flow through the roof. The solar reflectance (p) determines the fraction of the solar radiation incident from all directions that is diffusely reflected by the surface. The thermal emittance (c) describes how well the surface radiates energy away from itself as compared with a blackbody operating at the same temperature. Peak radiation from roofs occurs in the far-infrared region for temperatures on the order of 150°F and is sometimes referred to as the infrared emission. The thermal emittance represents the total hemispherical release of electromagnetic radiation over all wavelengths with peak radiation in the far infrared part of the spectrum.
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