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  Thermal Bridging Calculation Tool

The Thermal Bridging Calculation Tool determines the thermal performance of cavity insulated timber framed walls. It may also be used to determine the steady state R-value (U-value) and compare results with a simple one-dimensional isothermal plane calculation for the same relative framing ratio.

The excel spreadsheet tool may be used to investigate:

  • Changing overall window/door areas
  • Changing the size of individual windows and doors.
  • The benefits of increasing insulation R-value
  • Changing glazing type
  • Eliminating unnecessary framing elements

The tool also produces a visual representation of the heat flow like what is seen with a thermal imaging camera.


The basis of the tool is 3D finite element pre-modelling using 650 mm x 650 mm face areas represented by a grid of 13 x13 cells with size 50 mm x 50 mm. These parts are then joined as sections of wall which can be added together to create a complete length of wall for analysis. 


If you have any feedback or questions, please call Ian Cox-Smith 04 237 1170.