Trial / Demo
As energy standards tighten, accurately accounting for thermal bridging is now essential for compliance and performance. In a recent technical webinar, our experts showed how IESVE’s detailed thermal bridging capability enables engineers to model bridges using Psi and Chi values, Y-values and how to account for composite layers – all within a streamlined, physics-based workflow.
The questions from engineers worldwide revealed clear, consistent themes. Here’s what practitioners are really asking.
IESVE does not calculate Psi or Chi values from geometry or materials. Instead, it allows you to apply pre calculated values from built in datasets (e.g. ASHRAE 90.1, EN ISO 14683, UK NCM) or your own externally calculated values - then assess their impact dynamically within the full building model.
Non repeating thermal bridges are algorithmically identified by the VE’s physics based Apache engine based on the model geometry. You don’t need to manually draw them, but you can interrogate, visualise, and refine how they’re applied.
The terminology may not be intuitive, but it’s fundamentally about how often and where heat loss occurs.
If a window U-value is calculated to ISO 10077 and already accounts for frame/glazing junction effects, you should not specify Psi values in VE for those specific internal junctions. However, the perimeter installation junction (window-to-wall) is a separate thermal bridge not covered by ISO 10077 and should still be accounted for in VE independently.
Yes. The thermal bridging workflow has been validated for use with UK Part L (SBEM and DSM), ASHRAE 90.1 and NECB methodologies. Psi values defined in the construction database can be applied consistently to actual models for compliance.
The Apache Thermal Bridging Report is available in the Content Store. It identifies thermal bridges in your model for clearer building performance insights.
The script generates a CSV file detailing every thermal bridge by room and surface, including length or count, Psi or Chi value, and flux factor.
At the early design stage, the Simple Method enables quick, high level assessment without detailed thermal bridge modelling - ideal while geometry and constructions are still evolving. Once the design is fixed, apply rigorous Psi based calculations (using built in or custom values) to accurately assess energy performance and regulatory compliance.
No noticeable impact on simulation time. Thermal bridges are incorporated into the overall heat balance, and their effects are included in room loads and system sizing, improving result fidelity without slowing analysis.
Yes. Accurate thermal bridging improves overall model fidelity and can influence overheating assessments, surface temperatures, and condensation risk indicators such as Frsi (surface temperature factor) values.
Advanced users can:
• Apply custom Psi datasets aligned to national standards
• Use the VE Python API to automate data handling
• Interrogate results at building, space, or façade level
This flexibility supports both regulatory and advanced performance workflows.
What stood out most wasn’t just the volume of questions, but how closely they aligned. Engineers are no longer asking if thermal bridging matters, but how to model it accurately, efficiently, and defensibly.
If you’re tackling these questions on your own projects, you’re not alone, and the tools to address them are now firmly in place.
If you’d like to see how these principles are applied in practice, you can:
• Watch our on demand Thermal Bridging webinar
• Explore the latest thermal bridging workflows in IESVE
• Or speak with our team about applying this approach to your projects
