GB/T 2680-1994 Determination of light transmittance, solar direct transmittance, total solar energy transmittance and ultraviolet transmittance for glass in building and related glazing factors
Determination of light transmittance, solar direct transmittance, total solar energy transmittance and ultraviolet transmittance for glass in building and related glazing factors
This standard specifies the determination conditions and calculation formulae of light transmittance (reflectance), solar direct transmittance (reflectance and absorptance), total solar energy transmittance and ultraviolet transmittance (reflectance), hemispherical emissivity and shading coefficient for glass in building.
This standard is applicable to the determination of optical performance for the glass in building and its single and multiple glazing units.
2 Determination Conditions
2.1 Sample
2.1.1 The samples of general glass in building and single glazing units shall be the glass slices of the same material.
2.1.2 The samples of multiple glazing units shall be the combination of single glass slices of the same material.
2.2 Standard sample
2.2.1 In the determination of spectral transmittance, an air layer of the same thickness as the sample shall be used as a reference standard.
2.2.2 In the determination of spectral reflectance, the reference whiteboard configured with instrument shall be used as the reference standard.
2.2.3 In the determination of spectral reflectance, the standard specular reflector shall be used as the working standard, such as an aluminized mirror, instead of a perfect reflecting diffuser.
2.3 Instrument
2.3.1 Spectrophotometer, equipped with a specular reflection unit in determination of spectral reflectance.
