Overheating Assessments UK | Part O & TM59 Compliance
If you are planning a new residential development, you will likely need an overheating assessment to meet current Building Regulations. In particular, Part O requires developers to assess and reduce overheating risk in new homes.
At Assessment Hive, we provide professional overheating assessments across the UK. We help developers, architects and consultants achieve compliance quickly while improving building performance. In addition, we offer both simplified Part O assessments and TM59 dynamic thermal modelling, depending on your project requirements.
We support projects of all sizes. Whether you are building a single dwelling or a large residential scheme, we provide clear guidance, fast turnaround times and reliable results.
🔥 What Is an Overheating Assessment?
An overheating assessment evaluates the risk of excessive indoor temperatures within a building. As a result, it ensures that occupants remain comfortable during warmer months.
In recent years, overheating has become a major concern. This is because modern buildings are more airtight and highly insulated. Consequently, without proper ventilation and design, internal temperatures can rise quickly.
For this reason, overheating assessments often work alongside SAP Calculations and Air Tightness Testing. Together, these assessments help balance energy efficiency with thermal comfort.
📍 When Are Overheating Assessments Required in the UK?
Overheating assessments are primarily required for new residential buildings in England under Part O. However, they are also becoming more common across the wider UK as part of good design practice.
Typically, you will need an overheating assessment if:
- You are constructing a new dwelling or block of flats
- Your design includes large areas of glazing
- Natural ventilation is limited
- Your project is located in an urban or high-risk area
- Planning authorities request overheating analysis
In addition, many local authorities now expect overheating assessments at planning stage. Therefore, including them early in your project can help avoid delays.
🏗️ Part O Overheating Assessments Explained
Part O focuses on reducing solar gains while ensuring adequate ventilation in new homes. As a result, it plays a key role in preventing overheating.
There are two main compliance routes:
Simplified Method
Firstly, the simplified method uses standard criteria based on glazing, orientation and ventilation. Therefore, it suits straightforward and lower-risk developments.
Dynamic Thermal Modelling (TM59)
Alternatively, TM59 modelling provides a more detailed analysis. It simulates internal temperatures using specialist software. As a result, it is required for more complex or higher-risk projects.
Typically, TM59 applies to:
- Flats and apartments
- High-density developments
- Buildings with restricted window opening
- Urban locations
In most cases, we carry out this modelling alongside SAP Calculations. This ensures that both overheating risk and energy performance are considered together.
🌆 Overheating Assessments in London and Urban Areas
Urban developments often face higher overheating risk. For example, London experiences increased solar gains, higher external temperatures and limited ventilation options.
As a result, many developments require TM59 dynamic modelling to demonstrate compliance. In particular, apartment schemes and dense urban sites often fall into this category.
If your project is based in London, you should also consider local planning requirements. Therefore, you can visit your London overheating page for more detailed guidance.
In addition, overheating assessments are frequently included within Energy Statements. This helps demonstrate compliance with planning policy and supports your overall energy strategy.
📊 Overheating Assessments for Planning Applications
Overheating assessments play an important role in planning applications. In particular, local authorities want to ensure that new developments provide acceptable living conditions.
Therefore, these assessments help demonstrate that your project:
- Meets thermal comfort standards
- Aligns with planning policy
- Reduces long-term overheating risk
Moreover, including overheating analysis early in your design process improves your chances of approval. As a result, you can reduce the risk of delays and redesign.
🔄 How Overheating Links to Other Assessments
Overheating assessments form part of a wider compliance strategy. Therefore, you should not consider them in isolation.
Instead, they work closely with:
- SAP Calculations for energy and carbon compliance
- Energy Statements for planning submissions
- SBEM Calculations for mixed-use developments
- Air Tightness Testing for ventilation performance
When you coordinate these assessments early, you can streamline compliance and avoid costly design changes.
⚙️ Our Overheating Assessment Process
We follow a clear and efficient process. As a result, you can move forward with confidence.
- First, we review your architectural drawings and specifications
- Next, we assess overheating risk using Part O or TM59 modelling
- Then, we provide clear recommendations where required
- After that, we produce a fully compliant overheating report
- Finally, we support you through planning or Building Control
This structured approach ensures a smooth and stress-free experience.
⭐ Why Choose Assessment Hive?
There are several reasons to work with us.
Firstly, we deliver fast turnaround times.
In addition, we provide clear and practical advice.
Furthermore, we offer nationwide coverage.
We also specialise in Part O and TM59 compliance.
Finally, we have strong experience with complex and urban developments.
As a result, you can rely on us to deliver accurate and efficient overheating assessments.
❓ FAQs – Overheating Assessments UK
Are overheating assessments required across the UK?
Part O applies in England. However, many projects across the UK still require overheating assessments as part of planning or best practice.
What is the difference between Part O and TM59?
Part O sets the compliance requirements. In contrast, TM59 provides the detailed modelling method used for complex buildings.
Do all new builds require TM59?
No. In some cases, the simplified method is sufficient. However, many developments still require TM59 modelling.
When should I arrange an overheating assessment?
Ideally, you should arrange it at the early design stage. This helps prevent delays and reduces the risk of redesign.
📞 Get a Quote for Overheating Assessments UK
If you need an overheating assessment anywhere in the UK, we can help.
We provide fast, reliable Part O and TM59 assessments. In addition, we support both planning applications and Building Regulations compliance.
👉 Contact us today to discuss your project and receive a competitive quote.
✔ Quick turnaround
✔ Local qualified assessors
✔ Clear, actionable reports
✔ Fixed, affordable pricing
📞 Call us on 020 7183 3240
📧 Email us at [email protected]
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