Transmission, reflection and absorption

Transmission, reflection and absorption

Especially in connection with solar control glass, three terms - and thus also three numerical values - are of central importance.

  • Reflection - reflection of sun rays; mirror effect.
  • Transmission - Letting the sun's rays through.
  • Absorption - Absorption of solar radiation; dark surface.

None of these three properties exists in pure culture in glass as a building material. Each glass allows a certain amount of radiation to pass through (transmission) and stops part of it by absorption and reflection. The sum of reflection, transmission and absorption is always 100 percent.

Reflection
Glass Light reflection
Transmission
Glass Light transmission
Absorption
Glass Light Absorption

In radiation physics, a distinction is made between light (visible range of the spectrum) and energy (total range of the spectrum). The physical values are defined accordingly.

  • Light transmission/transmission factor (LT)
    The degree of light transmission of a glazing describes the percentage of solar radiation in the visible light range (380 - 780 nm), which is transmitted from the outside to the inside.
  • Light absorption/degree of light absorption (LA)
    The degree of light absorption is the proportion of solar radiation in the visible range (380 -780 nm) that is absorbed by the glazing.
  • Light reflection/degree of light reflection (LR)
    The degree of light reflection is the percentage of solar radiation in the visible light range (380 - 780 nm) that is reflected outwards.
  • Radiative transmission/degree of transmission (ST)
    The degree of radiation transmission, also called the degree of energy transmission, describes the proportion of radiation in the entire solar spectrum that is transmitted through the glazing.
  • Radiation absorption/radiation absorption coefficient (SA)
    The radiation absorption coefficient or energy absorption coefficient is the proportion of radiation in the entire range of the solar spectrum that is absorbed by the glazing.
  • Radiation reflectance/radiation reflectance (SR)
    The degree of radiation reflection or energy reflectance of a glazing indicates the proportion of radiation in the entire solar spectrum that is directly reflected outwards by the glazing.