Profile of emissivity
emissivity is the ratio of the radiant force of the actual object to the radiant force of the black body at the same temperature, which is a value less than 1. Depends on the type of substance, temperature, wavelength, direction, and surface conditions. The emissivity of the polished metal surface is low, but the surface roughness or oxidation is significantly improved. The emissivity of most building materials is between 0.8 and 0.95.