Overheating Assessments & Part O Overheating Assessment

Our overheating assessments provide detailed, technical analysis to identify and mitigate overheating risks in residential and commercial developments. As part of our Part O overheating assessment services, we ensure full compliance with UK building regulations while maintaining optimal thermal comfort for occupants. Using advanced modelling and practical design guidance, we help architects and developers create climate-resilient buildings that perform efficiently in both current and future conditions. Our overheating assessments not only support planning and compliance requirements but also enhance building performance, occupant wellbeing, and long-term sustainability.

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Understanding Overheating Risk

As buildings become more airtight and energy efficient, managing internal heat is increasingly important to ensure occupant comfort and long-term performance. Our overheating assessments use detailed overheating calculations to identify potential risks at an early design stage, allowing issues to be addressed before construction. As part of our Part O overheating assessment services, we help architects and developers achieve full compliance with UK building regulations while reducing reliance on mechanical cooling. By combining accurate analysis with practical design strategies, we support the creation of comfortable, sustainable, and climate-resilient spaces.

Thermal comfort assessment

Our Assessment Process

1. Design Review

Analysis of layouts, glazing, orientation, and ventilation strategies.

2. Thermal Modelling

Simulation of internal temperatures using Part O or dynamic modelling methods.

3. Risk Evaluation

Identification of rooms and periods vulnerable to overheating.

4. Mitigation Strategy

Clear, practical design recommendations to achieve compliance.

Key Factors Assessed

  • Internal Heat Gains – Occupants, appliances, and lighting.
  • Solar Gains – Glazing size, orientation, and shading.
  • Ventilation – Natural and mechanical airflow strategies.
  • Thermal Mass – Ability of materials to absorb and release heat.
  • External Conditions – Local climate and urban heat effects.

Regulatory Compliance

We assess developments against Approved Document Part O and provide documentation suitable for planning submissions and building control approval.

Assessment Methods

Both simplified compliance checks and detailed dynamic thermal modelling are available depending on project complexity.

Solar Control

External shading, brise-soleil, and solar control glazing.

Ventilation

Cross-ventilation, night cooling, and purge strategies.

Passive Design

Optimised layouts, thermal mass, and fabric-first measures.

Future Proofing

Design responses aligned with future climate scenarios.

Why Are Overheating Calculations Important?

  • Health & Comfort: Prevents heat stress, especially for vulnerable individuals.
  • Regulatory Compliance: Meets local and national guidelines (e.g., Part O of UK Building Regulations).
  • Energy Efficiency: Reduces reliance on active cooling, lowering energy demand.
  • Climate Resilience: Ensures buildings can withstand future climate conditions.

Key Factors in Overheating Calculations:

  • Internal Heat Gains – Assesses heat from occupants, appliances, and lighting.
  • Solar Gains – Evaluates sunlight exposure through glazing and building orientation.
  • Ventilation & Airflow – Considers natural and mechanical ventilation effectiveness.
  • Thermal Mass – Measures the building’s ability to absorb and release heat.
  • External Factors – Considers urban heat island effects and local climate data.

Overheating Assessment Methods:

  • Dynamic Thermal Modelling – Uses software to simulate heat performance.
  • Simplified Compliance Checks – Follows prescriptive methods in Building Regulations (AD-Part O).

To mitigate overheating, strategies like external shading, high-performance glazing, night-time ventilation, and passive cooling techniques are often recommended.

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Simple Process for Overheating Compliance

At A+E Consultancy Ltd, we provide clear and reliable overheating assessments for new buildings. Our goal is to help you meet Building Regulations and keep indoor spaces comfortable. We use a simple process that is easy to follow and quick to apply.

Step-by-Step Approach

We use a specific approach when conducting each Part O overheating assessment:

  • 1. Project Review: We examine the plans, layout, and orientation of the building. This is a preliminary measure, which can help identify potential problems at an early stage.
  • 2. Thermal Modelling: We simulate the accumulation of heat in the different rooms. We also take into account the space being exposed to the sun and its intended use.
  • 3. Risk Check: We identify rooms that may have overheating risk. We also refer to the rules in Part O.
  • 4. Design Advice: We provide simple fixes, which can include shading, glazing specification, and ventilation.
  • 5. Final Report: We provide a clear report. It shows how your design meets compliance.

Why It Is Important

Modern highly insulated buildings trap heat inside. This can make rooms uncomfortable. Our overheating assessments help prevent this problem early.

Key benefits include:

  • Better thermal comfort
  • Reduce the need for cooling systems
  • Improved energy use
  • Full compliance with Part O

Support for Your Project

We work closely with architects and developers. Our team gives fast and practical advice. This helps avoid delays and extra costs.

A proper Part O overheating assessment ensures your project stays on track. It also improves the long-term value of your building.

With A+E Consultancy Ltd, you get simple, clear, and effective support for overheating compliance.

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Frequently Asked Questions

What is overheating assessment, and is it a legal requirement?
It’s an assessment that checks whether a new residential building is likely to overheat, and it’s been a mandatory part of Building Regulations in England since Part O came into force in June 2022. It applies to new homes and residential-style buildings such as care homes or student accommodation. Without it, you won’t get sign-off from building control.

What’s the difference between the simplified method and dynamic thermal modelling for Part O?
The simplified method is a quicker, prescriptive check based on glazing size and ventilation, and it suits buildings that are unlikely to have overheating issues in the first place. Dynamic thermal modelling, based on CIBSE TM59, is a more detailed simulation and gives more design flexibility where the simplified route would fail. Highly insulated, heavily glazed, or unusually shaped buildings usually need the dynamic route.

What factors go into an overheating assessment?
The main ones are internal heat gains from people and appliances, solar gains through glazing, how well the building ventilates, its thermal mass, and external conditions like local climate and urban heat effects. Each of these is modelled together rather than looked at in isolation, since it’s the combination that determines actual overheating risk. Getting the glazing and ventilation strategy right early tends to solve most problems.

When in the design process should an overheating assessment be carried out?
As early as possible, ideally once the layout, glazing, and orientation are settled but before drawings are finalized for planning or building control. Catching a likely overheating issue at this stage means it can usually be fixed with shading, glazing changes, or ventilation tweaks. Leaving it until later often means far more costly redesign work.

What happens if my building fails the overheating assessment?
It’s not the end of the process. We’ll usually recommend practical fixes, things like external shading, solar control glazing, improved cross-ventilation, or night-time cooling strategies, and then re-run the assessment to confirm compliance. Most schemes pass once these adjustments are made, particularly if the issue is caught at the design stage rather than after construction.

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