TM59 Overheating Calculation

Overheating Calculations (TM59) – Dynamic Thermal Modelling for Part O Compliance

Professional TM59 Overheating Assessments for New Developments
We provide fully compliant CIBSE TM59 overheating calculations using advanced dynamic thermal modelling to support planning applications, building control submissions, and sustainability strategies for residential developments across England.
Our reports are accepted by local councils and meet the latest Building Regulations Part O (2021) requirements.

Whether you are a developer, architect, energy consultant, or planning agent, we deliver fast, accurate, and council-ready overheating assessments for flats, houses, mixed-use schemes, conversions, and large-scale residential blocks.

 
What Is a TM59 Overheating Calculation?
CIBSE TM59 sets the industry standard method for assessing summertime overheating risk in residential buildings.
Using dynamic simulation software such as DesignBuilder, IES VE, or SAP-linked tools, we model your building hour-by-hour to determine whether internal conditions exceed acceptable temperature thresholds.

Our modelling includes:

Internal gains (people, appliances, lighting)
Solar gains and façade exposure
Ventilation effectiveness
Window opening schedules
Shading devices and blinds
Thermal mass and construction materials
Weather files (DSY1, DSY2, DSY3 – relevant to your region)
We provide all required TM59 criteria, including:

TM59 – Criterion A: Living rooms, kitchens & bedrooms
TM59 – Criterion B: Bedrooms (night-time overheating)
 
Part O – Building Regulations Overheating Requirements
Since June 2022, Part O (Overheating) is a mandatory requirement for all new residential dwellings in England.

Part O requires designers to demonstrate effective:

Limiting solar gains
Providing adequate ventilation for heat removal
Using dynamic modelling (TM59) where the simplified method fails or is not suitable
Assessing noise, security, and pollution constraints affecting window opening
Providing mitigation strategies (shading, glazing, ventilation design)
Our reports include all mandatory Part O elements:

Approved Document O compliance summary
DSY weather file justification
Openable window area calculations
Noise/pollution/security constraints (if applicable)
Full TM59 dynamic model and simulation outputs
 
Council Requirements & Planning Expectations
Many planning authorities now demand TM59 or Part O overheating calculations at planning stage or as a pre-commencement condition.

Local councils typically require:

A full TM59 Dynamic Overheating Assessment
Demonstration of thermal comfort strategies for all dwelling types
Evidence that the design avoids reliance on mechanical cooling
Mitigation plan if a dwelling fails (shading, glazing changes, ventilation improvements)
Compliance with London Plan (Policy SI 4) for London boroughs
We regularly supply reports for:

London Boroughs (highest frequency of TM59 requests)
Manchester, Birmingham, Leeds
Bristol, Reading, Milton Keynes, Cambridge, Oxford
Coastal and high-density councils requiring overheating risk analysis
All reports are formatted to meet council expectations and are accepted without issues.

 
Who Needs a TM59 Dynamic Overheating Report?
Our TM59 assessments are suitable for:

New-build residential dwellings
Flatted developments and apartment blocks
Permitted development conversions
High-glazing and south-facing designs
Urban heat-island zones
Student accommodation
Build-to-rent projects
Mixed-use buildings with residential units
If your council has requested an overheating calculation, we can deliver quickly and clearly.

 
Our TM59 / Part O Report Includes
✔ Full dynamic simulation using TM59 methodology
✔ Part O compliance statement
✔ Weather file analysis (DSY1,2,3)
✔ Ventilation effectiveness & openable area calculations
✔ Solar gain assessment
✔ Demonstration of mitigation strategies
✔ Detailed failure points & improvement options (if required)
✔ Plans, modelling screenshots, and overheating maps

 
Why Choose Us?
Fast turnaround – urgent submissions available
Accurate modelling using approved software
Experienced energy & building performance consultants
Reports accepted by councils across England
Clear, planner-friendly documentation
We guide you through the entire overheating compliance process from design concept to final sign-off.

 
Get a TM59 / Part O Overheating Calculation Today
If your project requires an overheating assessment, we can help immediately.

Contact us for a quote or send your drawings (plans, elevations, sections) to begin your TM59 model.

TM59 overheating calculations and Part O compliant dynamic thermal modelling for new dwellings. Council-approved reports for planning and building control.

Fast TM59 overheating assessments and Part O modelling. Council-ready reports for planning applications and building regulations compliance.
Professional dynamic thermal modelling for TM59 and Approved Document O. Accurate overheating reports for residential developments.
Fully compliant TM59 overheating calculations for flats and houses. Part O ventilation, solar gain, and dynamic modelling included.