What is the fRsi value?
The temperature factor f*Rsi is a dimensionless quantity for the assessment of thermal bridges. The higher the temperature factor, the better the thermal insulation in this area. A small factor indicates a low room-side surface temperature.
By entering the surface temperature, air temperature inside and outside, the temperature factor f*Rsi is determined. The result should be greater than 0.7, otherwise there is no longer any condensation on the surface and the risk of mould formation increases.
In order to reduce the risk of mould formation through constructive measures, the temperature factor fRsi must meet the minimum requirement fRsi ≥ 0.70 at the most unfavourable point for all constructive, shape-related and material-related thermal bridges that deviate from DIN 4108 Supplement 2. The temperature factor can be used as a parameter for assessing the energy quality of window elements.