Solar energy is radiation with a wavelength from 300 to 4000 nm, which includes ultraviolet radiation (300 to 380 nm), visible light (380 to 780 nm) and near-infrared radiation (780 nm to 4000 nm).
External reflectance is the percentage of solar radiation reflected from the glass surface.
Absorption is the absorption of solar radiation by the glass
Transmittance is the percentage of solar energy that directly passes through the glass surface.
The total amount of reflected energy, absorbed energy, and the energy that passes through should be equal to 100%.
Another important indicator is emissivity. This is a value that describes the ability to radiate the absorbed energy in both directions - inside and outside the room. The emissivity of glass can be changed by applying a thin coating of metals, including silver, to one of its sides. Such glass is called low-emission glass or glass with a low-E coating.
