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Cool Roof Rating Council [60] (CRRC) has created a rating system for measuring and reporting the solar reflectance and thermal emittance of roofing products. This system has been put into an online directory of more than 850 roofing products and is available for energy service providers, building code bodies, architects and specifiers, property ...
ANSI/ASHRAE/IES Standard 90.1: Energy Standard for Buildings Except Low-Rise Residential Buildings is an American National Standards Institute (ANSI) standard published by ASHRAE and jointly sponsored by the Illuminating Engineering Society (IES) that provides minimum requirements for energy efficient designs for buildings except for low-rise residential buildings (i.e. single-family homes ...
In architecture, light reflectance value (LRV), is a measure of visible and usable light that is reflected from a surface when illuminated by a light source. [1] The measurement is most commonly used by design professionals, such as architectural color consultants , architects , environmental graphic designers and interior designers .
While directional-hemispherical reflectance factor is calculated for a single angle of incidence (i.e., for a given position of the Sun), albedo is the directional integration of reflectance over all solar angles in a given period. The temporal resolution may range from seconds (as obtained from flux measurements) to daily, monthly, or annual ...
Spectral hemispherical reflectance: R ν R λ — Spectral flux reflected by a surface, divided by that received by that surface. Directional reflectance: R Ω — Radiance reflected by a surface, divided by that received by that surface. Spectral directional reflectance: R Ω,ν R Ω,λ — Spectral radiance reflected by a surface, divided by ...
Jones's glossmeter used a geometric configuration of 45°/0°/45° whereby the surface was illuminated at 45° and two incident reflective angles measured and compared at 0° (diffuse reflectance) and 45° (diffuse plus specular reflectance). Jones was the first to emphasize the importance of using goniophotometric measurements in studies of gloss.
When reflection occurs from thin layers of material, internal reflection effects can cause the reflectance to vary with surface thickness. Reflectivity is the limit value of reflectance as the sample becomes thick; it is the intrinsic reflectance of the surface, hence irrespective of other parameters such as the reflectance of the rear surface.
Thermal emittance or thermal emissivity is the ratio of the radiant emittance of heat of a specific object or surface to that of a standard black body.Emissivity and emittivity are both dimensionless quantities given in the range of 0 to 1, representing the comparative/relative emittance with respect to a blackbody operating in similar conditions, but emissivity refers to a material property ...