Thermal modelling is a vital step in building design especially in today’s industry where efficiency is key. It gives architects, engineers and specifiers a clear picture of where heat loss can occur before construction begins, exposing the junctions where the building envelope is compromised by conductive materials such as steel or concrete.
Left unaddressed, these thermal bridges drive up energy consumption, reduce internal comfort and increase the risk of condensation and mould. Accurate modelling of architectural plans allows these weak points to be highlighted, with solutions selected at the initial design stage rather than discovered after completion.
How Thermal Modelling Is Used in Building Design
Thermal modelling uses software-based simulation to map heat flow across a building’s junctions, calculating temperature gradients, U-values and heat loss at specific details such as balconies, parapets, column bases and slab edges.
It is a key design tool in the construction process which produces a thermal bridging diagram, detailing exactly where heat loss can occur, how severe it is and what level of interruption is needed to bring it back in line with performance targets.
Using Thermal Bridging Models to Assess Heat Loss
Thermal bridging models are essential for assessing the extent of a building’s heat loss, especially for projects targeting Passivhaus, Part L compliance, or a low psi-value strategy. By calculating the K and R values, you can work out the overall efficiency of the building and therefore help to specify the right products for your project. It also helps to identify the applications where heat loss occurs and where thermal break products need to be installed.
Thermal Modelling in Construction Design Stages
Thermal modelling delivers the most value when it’s introduced early and revisited as the project develops through the design stages. For instance consulting a thermal model at RIBA stage 0-2 helps establish which junctions are likely to be problematic and informs the structural strategy before details are locked in.
By the time the construction has then progressed to technical design, models have become more detailed, feeding directly into U-value calculations, SAP/SBEM assessments and the specification of thermal break products at individual junctions.
Leaving thermal modelling until late in the design process, or treating it as a compliance box-ticking exercise, limits its effectiveness. Retrofitting a thermal break solution into a detail that’s already fixed is more difficult, albeit not impossible, but won’t be as effective as designing the junction around one from the outset.
Interpreting Thermal Bridging Diagrams for Specification
Thermal bridging diagrams typically use a colour-graded temperature key to show how heat moves through a junction, with warmer colours highlighting areas of concentrated heat loss. For specifiers, the vital details to read are the location and severity of the thermal bridge, to ensure that these areas are addressed by implementing thermal break materials.
Frequently Asked Questions
Thermal modelling is used to simulate how heat moves through a building’s structure and identify junctions where conductive materials disrupt the building envelope.
By showing exactly where and how severe heat is escaping through a junction, thermal bridging models let designers compare options and select solutions that can address the problem, improving the efficiency of the building.
Thermal modelling is most effective when introduced early, ideally at concept or at one of the earliest design stages. This ensures problematic junctions can be identified before details are fixed. It must also be revisited as the project develops, feeding into U-value calculations and thermal break specification at technical design stage, rather than being left as a late-stage compliance check.
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