Reflectance & Emittance

Solar Reflectance

Solar reflectance capacity is fraction of the solar energy incident to a surface that is reflected (0 to 1.0). This is typically measured using an integrating sphere and the procedures described in ASTM E903 or E892. The visible reflectance is sometimes reported. The visual reflectance is typically measured only in the 400 to 700 nanometer wave length so the two reflectance’s are not equal. A typical white coating may have a visual reflectance of 0.9 but a total reflectance of only 0.80.

Infrared Emittance

Infrared emittance is the ability of a warm or hot material to shed heat in the form of infrared radiation (0 to 1.0). Infrared radiation is typically in the 5 to 40-nanometer range. Most building materials have emittances in the 0.9 range. Some bare metal have much lower emittances.

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