RJ Energy Consultants | Thermal Bridging Analysis 

Carrying out ψ PSI Value modelling on your building can not only save you money but can provide a much more accurate representation of the heat loss in the building

 ψ PSI Value Calculations

Thermal Bridging in buildings is accounted for in two ways: 

Repeating Thermal Bridging: These are bridges such as studwork in walls and joists in roofs. They are accounted for in the U-Value calculation for each fabric element (i.e. walls, floors and roofs)

Non Repeating Thermal Bridging: These occur at junctions and openings and are accounted for through ψ (PSI) Values

A ψ Value is used to determine the overall heat loss at a specific junction (such as wall to floor junctions and windows or door openings). 


How are they entered in energy assessments?

In SAP Calculations there are 3 options in SAP for modelling thermal bridging

1. Assume default figures for the heat loss at each junction type.

2. Use Approved Construction Details. 

3. Carry out numerical analysis to determine the heat loss at each junction type. 

In SBEM Calculations the option for Approved construction details is not available so you are forced to use default figures or carry out a calculation.

Why should I carry out these calculations?


  • Improve your results in SAP & SBEM

  • Save money throughout the build

  • Achieve an even better-performing building and EPC 

  • The calculation only needs carried out once - meaning it is highly suited to developers building multiple plots of the same house type

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