The Retrofit Academy Club returned on Thursday 6th November with a technical deep dive into one of retrofit’s most persistent challenges: identifying and managing thermal bridges.
Chaired by Clive Rowland, Lead Tutor at The Retrofit Academy, the session explored how understanding PSI calculations, FRSI risk and thermal bridge mitigation can improve design and reduce condensation problems in real homes. The expert panel featured Matthew Allcock (Associate Partner and Retrofit Technical Lead, Bailey Garner), Marina Kearn (Sustainability Consultant, Bailey Garner) and Sarsvati Joshi (Retrofit Technical Solutions Manager, EQUANS).
Clive opened by noting that thermal bridging is a recurring topic among retrofit professionals. “It’s something we all need to get a grip on,” he said. “If we don’t address it properly, we risk undoing the benefits of retrofit.”
Matthew began by outlining how PAS 2035 guides professionals to identify and mitigate thermal bridges across assessment, coordination and design stages. He showed examples of common problem areas such as window reveals, roof-wall junctions and meter boxes, stressing the importance of early assessment and competent design. “It’s about being proactive,” he said. “Spot the issues before you’re on site, and make sure details are right the first time.”
Marina followed with an in-depth look at how to spot and calculate problem thermal bridges. She demonstrated how thermography and 2D and 3D modelling can be used to measure performance, explaining that FRSI values above 0.75 indicate a low risk of condensation and mould. Using sample junctions, she showed how small detailing changes such as continuous insulation and thermal breaks can make a significant difference to performance.
Marina followed with an in-depth look at how to spot and calculate problem thermal bridges. She demonstrated how thermography and 2D and 3D modelling can be used to measure performance, explaining that FRSI values above 0.75 indicate a low risk of condensation and mould. Using sample junctions, she showed how small detailing changes such as continuous insulation and thermal breaks can make a significant difference to performance.
Following the presentations, the speakers took part in a panel discussion which allowed attendees to explore practical challenges in greater depth. Questions covered when to use 3D rather than 2D modelling, suitable insulation materials for shallow eaves, and practical solutions for walkway balconies and window returns. The speakers agreed that success depends on accurate data, collaboration between teams, and good workmanship on site to ensure results that stand the test of time.
Clive closed by thanking the panel and audience, noting that thermal bridging is an area where theory and practice must come together, “It’s about understanding the science and getting the details right on site”.
The next Retrofit Academy Club, Making Retrofit a Lifestyle Choice, will take place on Thursday 8th January. The session will explore how to inspire homeowners to embrace retrofit as part of everyday living.
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