What Are Part O Building Regulations?
Understanding Overheating
Part O of the Building Regulations was introduced to reduce the risk of overheating in new residential developments.
Approved Document O requires designers to demonstrate that buildings can limit unwanted solar gains and remove excess heat effectively, helping to improve occupant comfort and resilience during warmer weather. Assessments are typically undertaken using either the Simplified Method or Dynamic Thermal Modelling (TM59), depending on the type and complexity of the development.
Why Choose MES Building Solutions?
Trusted Overheating Assessors
MES Building Solutions provide practical, compliant Part O assessments tailored to the needs of developers, architects, and design teams. Our consultants work closely with project stakeholders to identify overheating risks early, develop cost-effective mitigation strategies, and deliver clear reports suitable for Building Control and compliance submissions.
Benefits
What is the Process?
Simple, Efficient, Clear
Our proven step-by-step process keeps your project on track and delivered on time.
Step 1
We review drawings, specifications, site information, and project requirements.
Step 2
An assessment is undertaken using the Simplified Method or Dynamic Thermal Modelling.
Step 3
Potential overheating risks are identified and design alterations are suggested.
Step 4
A clear report is prepared demonstrating compliance with Approved Document O.
Step 5
Our team remains available to support Building Control queries and design refinements.
What's Included?
Every Part O Assessment Includes
Recent Project Experience
Overheating Assessments
Our experienced consultants deliver reliable technical advice, detailed reporting, and ongoing support throughout the project lifecycle.
A new student accommodation complex in Bristol.
A Liverpool housing development comprising houses and apartments.
A large care home facility in Leicestershire.
A mixed-use recreational and residential scheme in South London.
What Our Clients Say
MES have always been great to work with and fast to process any projects we are working on with them.
LH, Design Engineer
Frequently Asked Questions
Part O applies to most new residential developments in England and compliance must be demonstrated as part of the Building Regulations process.
TM59 is a recognised methodology developed by CIBSE that uses Dynamic Thermal Modelling to assess overheating risk in residential buildings.
The assessment should ideally be undertaken during the design stage to identify potential risks before detailed design decisions are finalised.
Where overheating risks are identified, mitigation measures such as shading, improved ventilation strategies, or glazing specification changes can often be implemented to achieve compliance.
While Part O is primarily a Building Regulations requirement, overheating assessments can also provide valuable evidence during planning and design development.
Timescales vary depending on project size and complexity, but early engagement helps ensure compliance requirements do not impact project programmes.