g-value

g-value is the abbreviation for (total) energy transmittance and indicates the permeability of energy in transparent components. So how good z. B. a window lets the sun’s energy into the house.
If you want to use a lot of solar energy, the g-value should be as high as possible, if you want to keep out a lot of sun, the g-value should be as low as possible.

Glossary overview