Lower means better insulated. Useful for comparing constructions, but note that a good average U-value does not prevent mould at a specific cold junction, which is what the temperature factor addresses.
Related terms
- Temperature factor (fRsi)A measure of how warm an internal surface stays relative to indoor and outdoor temperature, used to assess mould risk.
- Thermal bridgeA path of higher heat loss through the building fabric, creating a locally cold internal surface.
- Performance gapThe difference between a building's modelled energy performance and its actual measured consumption.
Seeing this in your building?
The free diagnostic works out the mechanism from what you can see and measure, and tells you what it cannot conclude.