Enhancing Energy Efficiency with Bespoke Thermal Bridging Calculations

May 16, 2025

At Wincer Kievenaar, we can provide bespoke Thermal Bridging calculations to enhance your project’s energy efficiency.

Understanding Thermal Bridging (PSI-Values)

Thermal bridging has become increasingly significant in the construction industry. As the demand for energy-efficient homes grows, thermal bridging is recognized for its impact, potentially accounting for up to 30% of a building’s total heat loss. This shift is driven by evolving legislation and a focus on architectural detailing and construction practices.

Benefits of Thermal Bridging Calculations

  • Minimise heat losses
  • Reduce unwanted heat gains
  • Lower energy consumption
  • Create a more sustainable and comfortable living environment
  • Improve your SAP Rating
  • Prevent cold spots and reduce condensation risks

What is a PSI-Value?

A Psi value (Ψ) measures heat transfer through specific parts of a structure prone to thermal bridging. It indicates the additional heat lost in these areas compared to the main insulation. Lower Psi values are preferred as they signify better energy efficiency and warmth.

PSI-Value in SAP

The Standard Assessment Procedure (SAP) is the official method for evaluating the energy performance of dwellings, as per Approved Document Part L of the Building Regulations.

All new dwellings must include SAP calculations to comply with these regulations. The SAP assessment showcases the project’s thermal performance and energy efficiency.

Previously, default Psi-Value figures from Accredited Construction Details (ACDs) could be used. However, with the removal of ACDs, independent assessments are now common to provide accurate Psi values for SAP Assessments. Without these independent figures, higher default values are often applied, making it harder to pass the SAP Assessment and encouraging independent junction calculations.

Independent calculations allow for adjustments to improve thermal performance as needed.

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About the author


Scott Crane

Architectural Technician

Scott Crane joined the Practice in October 2012 and is now a valued member of the team as an Architectural Technician. In 2018 Scott got his First Class Honours Degree in Architectural Technology from London Southbank University.

Scott studyied for five years whilst still working full-time at Wincer Kievenaar Architects in a course that covered all subjects from contract law, carbon neutral construction, energy assessments and social housing.

Scott is now skilled at conducting thermal bridging calculations, which are crucial for energy and cost effective designs. With our in-house training, we can perform personalised heat loss calculations through junctions. This allows us to design homes that are more energy efficient, improving SAP performance ratings tailored to each project's materials. This results in savings and reduced heat loss. Additionally, we can carry out condensation analysis to ensure a healthier living environment for residents by identifying and mitigating any risks.

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