Walls, floors and roofs
Determine the U- and R-values of multilayer building elements.
Free online building physics calculator
U-value calculation for building elements
Calculate the thermal transmittance of walls, floors, roofs and ground-contact structures using calculation methods in accordance with EN ISO 6946 and EN ISO 13370.
- Repeating thermal bridges
- Multiple parallel heat-flow paths
- Corrections for fasteners and air gaps
- Ground-contact structures
- No registration or installation required
Features
More than a basic layer-by-layer calculation
ThermalCalcOnline can take into account several effects that are often omitted from simpler U-value calculators.
Repeating thermal bridges
Account for multiple parallel heat-flow paths and their percentage shares.
Corrections
Include the effects of mechanical fasteners penetrating the insulation and air gaps between insulation boards.
Ground-contact structures
Calculate the thermal transmittance of ground floors and other structures adjacent to the ground.
Basic concepts
What does U-value mean?
The U-value is the thermal transmittance of a building element, such as a wall, floor or roof. Its unit is W/m2K.
It expresses the heat flow through 1 m2 of a building element at a temperature difference of 1 K. The lower the U-value, the better the thermal insulation performance of the element.
The calculation takes into account the thermal resistance of the individual layers, any air layers, and the internal and external surface heat transfer resistances.
Calculation methods:
the calculator applies methods in accordance with EN ISO 6946
and EN ISO 13370.
The R-value (m2K/W) characterises thermal resistance. Additional heat losses at thermal bridges may be described using linear thermal transmittance values alongside U- and R-values.
Try it with a real construction build-up
No registration, download or installation is required.