Glossary
Passive solar heating – Energy production

Absorption coefficient; Coefficient d'absorption

Fraction "a" of the radiation absorbed by a material.

Coefficient de réflexion ; Reflection coefficient

Fraction "r" of the radiation reflected by the material.

Transmission coefficient; Coefficient de transmission

Fraction "t" of radiation through which the material passes.

Emissivity

The opposite of absorption: a material emits radiation by drawing on its internal energy store, so its temperature decreases and it cools.