ift Guideline WA-22engl/2 Thermally improved spacers - Part 3 Determining the representative Psi-values of facade profiles (Download)

In accordance with the product standard for curtain walling, EN 13830, one of the methods to determine the thermal transmittance U_CW of curtain walling is the calculation method set out in EN ISO 12631. For the calculation, it is necessary to use the thermal transmittances of mullions and transoms, U_m and U_t, and the glazing U_g as well as the linear thermal transmittances Psi_mg and Psi_tg. These Psi-values describe the heat loss caused by fitting the glass unit in the mullion / transom. The amount of this Psi-value varies depending on the spacer used in the insulating glass unit (IGU). A distinction is made between “conventional” spacers and thermally improved spacers. EN ISO 12631 contains a definition of a thermally improved spacer, which is summarised in the scope of this Guideline.

This article is also available in German.