Overheating Calculation
Part O Building Regulations

Overheating Calculation (Part O Building Regulations)

What is a Part O overheating calculation?

Part O of the Building Regulations in England sets out clear rules to limit overheating in new residential buildings. This regulation is about keeping indoor temperatures safe and comfortable for occupants, especially in summer, while reducing the need for energy-hungry cooling systems. Overheating calculations are a requirement for compliance. They show that your building design addresses the risks early and meets the standards needed for approval. Without these calculations, your project cannot move forward.

Who needs an overheating calculation?

If you are planning a new residential building in England, whether you are a housebuilder, architect, developer, or self-builder, then Part O applies to you. Some larger extensions or conservatories may also require an assessment, depending on their size and design. Getting these calculations done early can help you avoid project delays, costly design changes, and compliance risks. They also help protect occupant health, reduce future energy bills, and support your sustainability goals.

Why does it matter?

Uncontrolled overheating is now a leading concern for new homes, especially in cities or densely built-up areas. Part O compliance gives peace of mind to building owners and residents. It ensures that living spaces are not only legal but also pleasant to live in. It can also boost the appeal of your property by showing a commitment to comfort, safety, and energy efficiency.

Send us your project details and we’ll send a quote

Our overheating calculation services

We offer both standard and advanced approaches to Part O compliance, covering projects of all sizes and complexity:

Simplified method assessments

Quick calculations based on building area, window size, orientation, and ventilation. Best for standard house types or smaller projects.

Dynamic thermal modelling (DTM)

Detailed simulations using industry-leading software. This is suited to complex buildings or those with higher risk of overheating.

Clear compliance advice

Guidance on passive cooling measures, shading, ventilation, and other design choices to help you meet regulations and avoid unnecessary costs.

Integration with other compliance

We coordinate with SAP Calculations and Part L requirements for a joined-up approach to building control approval.

Simplified method assessments

Quick calculations based on building area, window size, orientation, and ventilation. Best for standard house types or smaller projects.

Dynamic thermal modelling (DTM)

Detailed simulations using industry-leading software. This is suited to complex buildings or those with higher risk of overheating.

Clear compliance advice

Guidance on passive cooling measures, shading, ventilation, and other design choices to help you meet regulations and avoid unnecessary costs.

Integration with other compliance

We coordinate with SAP Calculations and Part L requirements for a joined-up approach to building control approval.

Our overheating calculation process

01

Initial review

Share your plans and key information with our team.

02

Assessment selection

We advise on the right method (simplified or DTM) for your project.

03

Modelling and calculation

Our engineers carry out the calculations, using the latest approved methods and software.

04

Reporting and recommendations

We provide a clear, compliant report, along with practical advice for your build.

05

Support and sign-off

We respond to follow-up questions, update reports if your design changes, and help you through the approval process.

Why choose enevo for Part O overheating calculations?

Decades of experience supporting residential developers, architects, and self-builders across the UK.
In-house expertise in overheating, energy, and sustainability compliance for a seamless service.
Fast turnaround and clear communication at every stage.
Recognised by national housebuilders, regional contractors, and local authorities for technical quality and practical advice.
Strong track record of helping projects achieve first-time approval.

How can we help you
with your project?

Trusted, Time And Time Again

Harry gave me excellent advice and clear understanding on what BREEAM means as well about the specific accredited assessing required by professionals like Harry.

Angela Singh

Very efficient and professional service. Cant recommend enevo enough, glad I chose them for my project.

William Brannon

Very impressive on all aspects of energy calcs. Responsive and cost competitive. Highly recommended

Nick Spencer

enevo are always helpful, friendly and efficient in carrying out SAP calculations for our clients.

Lizzie Hicks

Dan at enevo has completed for us SBEM Calculations and EPC Certificates for 6 commercial units on an industrial estate. The cost of the works was very competitive and the service we received was second to none. With very limited time to get these works completed Dan worked round the clock (and into his annual leave!!) to ensure that our completion date was achieved with very little notice. Would highly recommend!

Mollie Belton

We have always found enevo to provide an excellent service in the preparation of SAP Calculations and Assessments as well as EPC Certificates for projects that they have worked on for us. They are also reasonably priced so we would certainly recommend them to anyone looking for this type of service.

Martin Booker

Used enevo from start to completion of our recent project of 2No. new builds. Services included SAP/EPC and property air testing. Great service, understanding of requirements and cost. Person friendly company and good with communication.

Mark Radcliffe

Very efficient, personal, professional service, with a quick report turnaround. Highly recommended if you're a self-builder trying to navigate the complexities of the latest regulations.

Edward Broadhead

Always efficient and prompt service, enevo are an asset to my company, having used their services on multiple developments I wouldn't hesitate to recommend them.

Mac Chappell

Great service with a fast turnaround. Communication was excellent throughout. Richard the engineer was polite and professional. Will certainly be using enevo again.

ECO PROPERTY DEVELOPMENTS LTD

What We Think

08/12/2025

Energy & Sustainability Planning Statements: What They Are and Why They Matter

Read Insight

24/11/2025

BREEAM Services – navigating Version 7, credits, and sustainable strategy

Read Insight

11/11/2025

JM Partnership joins enevo, strengthening Building Control coverage nationwide

Read Insight

04/11/2025

Breathing Easy – why indoor air quality testing matters

Read Insight

Regulator capacity and the Building Safety challenge in 2025-2026

Read Insight

We’re Ready To Help

Part O Building Regulations

We’re Ready To Help

Overheating Calculation

03301 901 200

info@enevo.co.uk

Overheating Calculation
Part O Building Regulations