What is the difference between the shading coefficient (Sc) and the selectivity coefficient (S) of glass?

Shading coefficient (Sc) is the ability of glass to block, reflect and block the passage of solar radiation. English is called shading coefficient, abbreviated as Sc, and domestic GB/T2680 is called shading coefficient, abbreviated as Se. The definition refers to the ratio of the total solar radiation transmittance of the tested glass to the total solar radiation transmittance of the common colorless transparent flat glass with a thickness of 3 mm.. The smaller the shading coefficient, the better the performance of blocking sunlight heat from radiating indoors.

The glass selectivity coefficient S reflects the ability of glass to transmit visible light, which is the selectivity coefficient in English.

Refers to the ratio of visible light transmittance TL to total energy transmittance G, and S = TL/g. The greater the selectivity coefficient of S glass, the higher the visible light transmittance.

For Low-E glass, it is generally desirable that the larger the shading coefficient (Sc) is, the better the selectivity coefficient (S) is.