What are reflectivity and emissivity and why are they important?
reflectivity is the percentage of solar energy reflected by the coating back into the atmosphere. The remaining energy that is absorbed increases the temperature of the roof surface. Higher reflectivity results in less absorbed energy which results in less potential heat gain. Emissivity is a measure of the coatings ability to emit absorbed solar energy as infrared radiation. higher emissivity will generally result in a cooler surface for two materials with the same reflectivity. The relationship between emissivity and roof temperature is complicated by factors such as conductivity of the roof surface and wind speed that will allow some lower emissivity surfaces to shed heat energy more efficiently.
Related Questions
- Remember that emissivity and reflectivity both play a part in the surface temperature of a roof. Back to Top Why does a white prepainted metal roof have a much higher emissivity than an unpainted metal roof?
- How do I find out the Solar Reflectivity, Emissivity, and Solar Reflective Index value of coatings?
- Does embossing complicate reflectivity/emissivity measurements?
