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