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The software we use in Numerical Thermal Modelling


To calculate thermal flows and asses condensation we need to utilise high powered computer modelling software.

When run on cutting edge hardware they can accurately calculate millions of iteration nodes and present the results in a way that can be put into a readable report. These reports can be used to show compliance with the building regulations and the design parameters for any given project.

Here we show the types of software that we use at The Wright Consultancy.

One Dimensional modelling software

We use 1D thermal modelling for a simple wall or rain screen when a simple U-value is required for a ‘layer cake’ build-up. There is an inside | wall | outside with no corners or interfaces such as a window jamb. BuildDesk-U is used for this task.

Below is an excerpt from the BuildDesk website.


BuildDesk software helps designers and energy assessors to calculate the energy efficiency of buildings for both Building Regulations and Energy Performance Certificate purposes.

BuildDesk U

  • Professional software for U-value calculation.

  • Includes Condensation Risk Analysis (CRA) and heat capacity calculation for assessing thermal mass.

Two Dimensional modelling software

If you have corners, interfaces (such as jambs, cills or heads), or require a Psi-value then 2D modelling is required. A Psi-value is the additional heat loss that is created due to the interface of elements such as those mentioned above. This is a more complex calculation and requires the use of advanced software. We use Bisco by Physibel which also allows for the  calculation of condensation Risk Analysis.

Below is an excerpt from the Physibel website explaining the uses for the software.

  • Thermal bridge analysis: heat loss calculation, surface condensation (ISO/FDIS 10211, ISO 13788)

  • Thermal transmittances of building components and elements (EN ISO 6946)

  • Thermal performance of windows, doors and shutters (EN ISO 10077-2)

  • Heat transfer via the ground (ISO 13370)

Three Dimensional modelling software

At times it is necessary to calculate a point heat loss such as a bracket or balcony penetration. Sometimes a complex steel frame junction with multiple intersecting beams or even variations within a transom/IGU interface need to be accounted for. This will require 3D modelling. We also need to calculate condensation Risk Analysis in 3D and so our application of choice is Trisco by Physibel.

Vapour transfer simulation

At times it is necessary to calculate vapour flow lines to analyse where the percolation of water vapour takes place. Analysing details in this way can can help us to understand where any drain points or additional vapour control layers need to be.

Below is an excerpt from the HTFlux website.


HTflux is an innovative software to for two-dimensional simulation of heat and water vapor transport. GLASER 2d, a unique method developed by HTflux applies the well known and proven Glaser method on two-dimensional geometries. This enables you to calculate dew point zones including condensation and evaporation amounts for two dimensional configurations.

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