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  • Shading Coefficients
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    Shading Coefficients

    The total shading coefficient is a measure of the total amount of the sun's energy passing through the glazing (known as the total solar heat transmittance or g value) compared with that through a single clear glass. The shading coefficient (SC) is derived by comparing the solar radiant heat transmission properties of any glass with a clear float glass having a total solar heat transmittance of 0.87 (i.e. clear float glass of 3 or 4 mm thick).

    The shading coefficient (SC) can be separated into long-wave and short-wave components, whose values are derived in exactly the same way, by comparing with the same property of 3 or 4 mm clear float:

    • The short wavelength shading coefficient (SWSC) is the direct solar heat transmittance divided by 0.87.
    • The long wavelength shading coefficient (LWSC) is the fraction of the absorptance released inwards, again divided by 0.87.

    Spectrum Calculation Program


    Pilkington Spectrum is a Windows-based glass performance model which enables you to quickly and efficiently calculate key properties of a wide range of single glazing and insulating glass units. Also available as an app for mobile devices, you can use Pilkington Spectrum to provide the following information:

    • Light and solar properties (transmittance, reflectance, absorptance, g value, etc.).
    • Centre pane Ug-value.
    • Sound insulation values.
    • Global Warming Potential (GWP), or carbon footprint.
    • Ultra violet (uv) transmittance and colour rendering index (Ra).
    • Other properties (e.g. pendulum body impact resistance, fire resistance, resistance to manual attack, etc.).
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