What are S.R.I. Figures ?
Solar reflectance index (SRI), is another measurement beginning to get some attention as a numerical expression of a coating’s overall ability to reject solar heat.

Total Solar Reflectance (T.S.R.) figures are expressed as a percentage falling between 0% and 100% dependent on a product’s Total Solar Reflectance as tested to ASTM C-1549 or ASTM E-903.

Emissivity or (Infrared emittance), is a measure of the ability of a surface to shed some of its heat in the form of infrared radiation away from the surface. The results from tests conducted to ASTM C-1371, express the emittance value as a percentage falling between 0% and 100% depending on the product’s performance.

Solar reflectance index (SRI), combines both the T.S.R.% reflectivity value and emittance value as a measure of a coating’s overall ability to reject solar heat. The (S.R.I.) index calculation is done in accordance with ASTM E 1980-01. The calculation is based on a mathematical formula that includes values for thermal emittance, total solar reflectance, solar absorbance, three convective coefficients, solar flux, the Stefan Boltzman constant, and various other coefficients.