What U-value and g-value mean

Increased thermal insulation = reduced heat loss

Technical parameters

• The basic characteristic required of insulating glass is nowadays increased thermal insulation, i.e. the greatest possible reduction of heat loss.

U-value

• is the basic unit of measurement in determining the heat loss of a building component

• indicates the amount of heat that passes through one m2 of a building component per unit time at an indoor/outdoor air temperature difference of 1 Kelvin

• the unit of measurement is ^W/m2K

• the lower the value, the better the thermal insulation of the building material

• a low U-value is the most important property of insulating glass

• low heat loss, due to better thermal insulation, leads to a higher surface temperature of the interior pane and thus to a more comfortable room

• allows the use of smaller thermal devices and thus offers economic and environmental advantages

g-value

• transmittance coefficient of the total solar energy, given in %

• consists of the direct energy transmission and the secondary inward heat output of the glazed surface due to absorbed solar rays

• through glass alone, the sun can heat rooms and contribute to heating at no additional cost

• what is welcome in winter can be unpleasant in summer, because the energy gained by the sun's rays means heating

• high thermal insulation is the right way to go, i.e. low U-value and not too high g-value

• insulating glass with a coated layer has become the technological standard

• they consist of at least two panes, one of which is coated with a very thin layer of noble metal, thus radically reducing heat loss