What Is Thermal Bridging?

Thermal bridges occur where there is a break in the continuity of the building envelope's insulation—typically at junctions between walls, floors, roofs, or around openings such as windows and doors. These areas facilitate increased heat flow, leading to energy loss, surface condensation, and the potential for mould growth.

Proper identification and quantification of thermal bridges early in the design process can significantly improve energy performance and occupant comfort, while reducing the risk of long-term moisture damage.

Why Thermal Bridge Modelling Matters

In today’s regulatory and climate-conscious environment, accurately accounting for thermal bridges is not only a best practice - it’s a necessity. Thermal bridging can account for up to 30% of total heat loss in poorly detailed buildings. It can also result in underperforming building fabric, undermining the performance of insulation, heating systems, and ventilation strategies.

Effective modelling supports:

• Reduced heating/cooling loads

• Enhanced thermal comfort

• Lower risk of condensation and mould

• Improved durability of building materials

• Smoother certification and compliance pathways

Service Offering: From Detail to Insight

Our 2D and 3D thermal bridge modelling service covers the full lifecycle of thermal junction analysis, tailored to suit the needs of architects, energy modellers, manufacturers, and developers. We use validated, high-performance software, depending on project requirements, to simulate heat transfer through complex building junctions.

We typically provide:

• 2D modelling: suitable for linear thermal bridges - details like wall-to-floor junctions, window jambs, and parapets—where the heat flow occurs predominantly in two dimensions. It is ideal for most typical construction details and is the most common method used in SAP and PassivHaus assessments.

• 3D modelling:  necessary for more complex junctions where heat flows in all three dimensions, such as corner junctions, balconies, or steel structural penetrations. 3D simulation allows for a much more detailed and accurate representation of real-world thermal behaviour and is especially valuable in high-performance building projects or where novel materials or systems are introduced.

• Calculation of linear thermal transmittance (Ψ-values) and point thermal transmittance (χ-values)

• Surface temperature factor (fRsi) analysis to assess condensation and mould risk

• Optimisation of detail performance through iterative modelling

• Modelling of proprietary construction products for BBA certification or performance declarations

Our team delivers all results with full graphical outputs, temperature gradient plots, and tabulated data, suitable for submission in energy models (SAP, PHPP, or dynamic simulation tools) or for use in technical assessments.

Standards and Guidance Followed

All our modelling and reporting follows best practice and is fully compliant with UK and EU standards. Key documents we reference include:

• BR 497 – Conventions for Calculating Linear Thermal Transmittance and Temperature Factors: The cornerstone of Ψ-value calculations in the UK, setting out standard conventions and boundary conditions for junction analysis.

• BRE Information Paper IP 1/06: Guidance on assessing the risk of mould growth and surface condensation via the internal surface temperature factor (fRsi).

• BS EN ISO 10211:2017 – Thermal Bridges in Building Construction – Heat Flows and Surface Temperatures – Detailed Calculations: The principal European standard for the calculation of 2D and 3D thermal bridges, ensuring internationally recognised accuracy and consistency.

• BS EN ISO 13788:2012 – Hygrothermal Performance of Building Components and Building Elements – Internal Surface Temperature to Avoid Critical Surface Humidity and Interstitial Condensation: Defines the threshold values and calculation approach for condensation risk.

Where required, we also follow PHI (Passive House Institute) modelling protocols to ensure compatibility with PHPP energy balance tools and certification schemes.

Beyond Compliance: Better Building Performance

While regulatory compliance is a common driver for thermal bridge modelling, our approach goes beyond minimum standards. Our goal is to optimise building performance holistically, by integrating modelling outcomes into broader conversations about fabric efficiency, airtightness, hygrothermal risk, and occupant health. We work closely with your design or technical team to interpret results and improve outcomes—not just to tick boxes, but to build better buildings.

Who We Work With

Our modelling services support a wide range of clients:

• Architects and designers seeking to improve building junction performance or meet SAP and building regulation requirements

• Product manufacturers developing thermal construction systems or seeking BBA certification

• Energy consultants requiring accurate Ψ-values to improve DER/TER margins or Passive House compliance

• Offsite construction firms looking to validate prefabricated details or develop standardised junction libraries

• Retrofit coordinators assessing the impact of junction upgrades as part of whole-house energy strategies