ASHRAE - American Society of Heating@ Refrigerating and Air-Conditioning Engineers@ Inc.
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ASHRAE 74-1988
Scope
Procedure Aof this method covers the measurment of spectral absorptance@ reflectance@ and transmittance of materials using spectrophotometers equipped with integrating spheres. Procedure C of this method covers the measurement of solar transmittance (terrestrial) of materials using a pyranometer@ and enclosure@ and the sun and sky as the source of radiation. Methods of computing solar-weighted radiant and luminous properties from the measured spectral values are specified in procedures Aand B@ which are applicable to materials having both specular and diffuse optical properties. Except for transmitting sheet materials that are inhomogeneous@ patterned@ or corrugated@ proceduresAand B of this method are preferred over procedures C@ D@ andE. Procedure B describes the calculation of luminous (photometric) transmittance and reflectance of materials from spectral radiant transmittance and reflectance data@ or both@ obtained from the performance ofProcedureAof this method. Procedure C of this method allows measurement of solar transmittance of materials in sheet form at normal incidence and at angles other than normal incidence and is applicable to transparent@ translucent@ textured@ or patterned sheet materials. ProcedureD ofthis method covers the measurement of solar photometric transmittance of materials in sheet form. Solar photometric transmittance is measured using a photometer (illuminance meter) in an enclosure with the sun and sky as the source of radiation@ the enclosure and method of test being specified in ProcedureC. The purpose ofProcedureDis to specify a photometric sensor to beused with Procedure C for measuring the solar photometric transmittance of sheet materials containing inhomogeneities in their optical properties. ProcedureEcovers the measurement of the solar radiant and luminous reflectances at normal incidence@ and at other angles@ of sheet materials that are opaque and which may also be textured or patterned. PURPOSE To develop astandard method for measuring and reporting the following solar optical properties of materials: spectral transmittance@ reflectance@ and absorptance between 320nm and 3000 nm in wavelength@ and total radiant and luminous transmittance and reflectance.
ASHRAE 74-1988 history
1988ASHRAE 74-1988 Method of Measuring Solar-Optical Properties of Materials