Overheating poses a serious risk in modern residential projects. As climates warm and buildings become more airtight and thermally efficient, new developments can trap excessive heat, harming occupant comfort, health, and energy use. An overheating assessment is central in design to prevent this, supported by allied services from expert consultants like Syntegra.
Why overheating matters in new homes
- In the UK, homes reporting overheating rose from ~18 % in 2011 to ~80 % in 2022¹.
- Under a 2 °C warming scenario, up to 90 % of homes may risk overheating2.
- Heat-related mortality is forecast to reach ~7,000 deaths annually by the 2050s due to climate change3.
- The UK’s Approved Document O (Part O) now mandates overheating mitigation in new residential buildings⁴.
These figures make overheating assessments essential for compliance and occupant comfort.
What is an overheating assessment?
An overheating assessment predicts how a building will behave in summer thermal conditions. It shows whether internal spaces risk exceeding comfort thresholds. Methods include:
- Dynamic Simulation Modelling (DSM): For complex projects or where simple checks fail.
- Simplified methods / Checklist-based assessments: For less complex or smaller schemes.
If a building fails the simplified route, DSM becomes necessary to demonstrate compliance with Part O.
Syntegra services that support Overheating Assessment
Syntegra offers a suite of services that complement and enhance overheating assessments — integrating design, regulation, sustainability, and building performance:
| Service | How it helps prevent overheating & improve outcomes |
| Building Simulation Modelling | Provides detailed thermal analysis, sunlight/daylight studies, and ventilation modelling to evaluate heat gains early in design. |
| Energy Consultancy | Optimises energy performance, reduces cooling demand, and ensures Part L compliance through efficient system design. |
| Sustainability Assessment (e.g. BREEAM, LEED, SKA, WELL) | Integrates thermal comfort and energy efficiency benchmarks into project sustainability goals. These assessments embed overheating mitigation strategies. |
| M&E (Mechanical & Electrical) Design | Mechanical ventilation, shading devices, solar control glazing, façade design, passive-cooling systems all flow through M&E design. Integrated design ensures overheating measures are physically designed in3. |
| Environmental Consultancy / Air Quality & Micro-Climate Analysis | Micro-climate effects (e.g. solar exposure, external shading, surrounding buildings) impact overheating. Air-quality and micro-climate studies help adjust design to local conditions. |
Key strategies to prevent overheating
To keep buildings cool, developers and designers can adopt these measures:
1. Early-stage design
Orient buildings for shading and cross-ventilation. Use dual aspect layouts wherever possible5 to aid with cross ventilation through openable windows
Optimise window area and use solar-control glazing (low g-value) on south-facing façades.
Embed thermal mass, dense materials absorb daytime heat and release it overnight.
2. Shading and external devices
Deploy external shading (e.g. louvers, brise-soleil, retractable awnings) to block solar gains before entering windows.
3. Natural ventilation & night purging
Design for crossflow and stack ventilation.
Openable windows and ventilated atria allow night-time cooling to flush heat.
4. Controlled mechanical systems
Use Mechanical Ventilation with Heat Recovery (MVHR) systems with summer bypass to purge heat.
Active cooling (e.g. split units) only after passive measures have been optimised.
5. Green infrastructure & microclimate
Introduce trees, green walls, green roofs and shading from landscape to reduce heat island effects.
Specify lighter-coloured externally reflective surfaces to reduce external absorption.
Integrating assessment into project workflow
- Concept / Feasibility stage — get early overheating risk analysis and energy modelling to set design layout.
- Detailed design stage — full DSM, simulation, M&E design, sustainability assessment.
- Planning / Certification — use reports for Part O compliance, BREEAM/LEED credits.
- Post-occupancy — monitoring, feedback, adjusting occupant guidance.
Syntegra’s services such as Building Control Compliance Testing also ensure that the as-built building performs as predicted.
comfortable buildings. Syntegra’s full range of services supports every stage of this process. Early integration saves cost, improves comfort, and reduces risk under rising temperatures.
Contact Syntegra Group today to discuss your Overheating Assessment an let our experts help you deliver sustainable designs that perform, now and in the future.
Footnote
1. Number of UK homes overheating soars to 80% in a decade, study finds…The Guardian, 2025.
2. Scoping out a new overheating index for buildings in the UK – Grantham Research Institute” (20 January 2025). LSE / Grantham Institute, 2025.
3. UK summertime overheating | Research and Innovation. Loughborough University projections.
4. Overheating: Approved Document O. GOV.UK
5. Overheating and dual aspects. Centre for Cities
You must be logged in to post a comment.