• Thermal transmittance U_g

The thermal performance U_g of insulating glazing (double or triple) depends on the emissivity of the coating used, the dimensions of the space(s) between the glass and whether or not argon gas is present.

This thermal performance is expressed in the form of the value U_g, which contributes significantly to the window's thermal performance (Uw). It is calculated according to EN 673 standard.

A U_g of 1.1 means that the energy loss is 1.1 Watt per square metre Kelvin (in conventional conditions).