Thermal Bridging and Psi Value Analysis: Silverthorne Lane, Bristol Case Study

At the Silverthorne Lane development in Bristol, JAW Sustainability carried out detailed thermal bridging calculations to assess junction performance and support energy-efficient building design.

This case study focuses on the party floor to external wall junction, where Psi values (linear thermal transmittance) were calculated using TRISCO thermal modelling software. The analysis compares a traditional masonry support detail against an alternative precast concrete solution incorporating Max Frank’s Egcobox thermal break system.

Thermal bridging is a critical factor in building fabric performance, directly influencing heat loss, condensation risk, and overall energy efficiency. Poorly designed junctions can lead to increased carbon emissions, reduced thermal comfort, and non-compliance with UK Building Regulations Part L.

The Silverthorne Lane project forms part of a large-scale student accommodation development in Bristol, delivering over 700 residential units.

JAW’s analysis evaluates how different construction details impact:

• Psi values and heat loss at junctions

• Thermal bridge performance and continuity of insulation

• Risk of condensation and mould growth (fRsi analysis)

The study demonstrates that incorporating thermally broken precast elements, such as the Max Frank Egcobox system, can significantly reduce heat loss and prevent condensation and mould growth.

You can find out more about the importance of Psi Values and Thermal Bridging by reading our bulletin post.

Click the download button below to read the full PDF of JAW's Max Frank Case Study.