Thoughtful, fast-growing force in sustainable consultancy harnessing analytical theory to deliver multiple projects. Rightly gaining national recognition.
Judges, Bristol Property Awards 2025
Overheating in buildings is an increasing concern in the UK, driven by climate change and the associated rise in internal temperatures. Whether you’re planning a new non-domestic building or managing an existing property, our Thermal Comfort Analysis using CIBSE TM52 assesses the risk of overheating and helps ensure thermal comfort throughout the year.
TM52 is the CIBSE methodology for assessing and mitigating overheating risk in non-domestic, “free-running” buildings – offices, schools, care homes and similar – whether existing or proposed. Using the CIBSE TM52 methodology, we evaluate three criteria: hours of exceedance, daily weighted exceedance, and upper limit temperature, to build a clear picture of thermal comfort across your building.
Our sustainability consultants use dynamic thermal simulation modelling to assess comfort levels and predict overheating risk, then identify practical mitigation strategies – from design changes to operational adjustments. The result is a clear report on overheating risk, applicable at design stage for new buildings or to existing properties already experiencing comfort issues, giving you the evidence you need to guide upgrades and keep your building comfortable, energy-efficient and compliant. Please see our FAQs below for more information.
Why work with us?
Experience
Our sustainability consultants have extensive experience in overheating assessments and commercial decarbonisation.
We pride ourselves on delivering decarbonisation advice to help our clients build and maintain lower carbon, energy-efficient properties.
Award-winning
Winner, Consultancy – 2025 Bristol Property Awards
Winner, Supply Chain Partner of the Year – 2025 Unlock Net Zero Awards.
Winner, Retrofit Assessor of the Year – 2023 Retrofit Academy Awards.
Highly Commended, Employer of the Year – 2023 Retrofit Academy Awards.
Speed
Project deadlines matter. We manage all data collection, modelling and reporting in-house – keeping your project moving without administrative delays.
We work to a standard two-week turnaround, with most reports delivered well within that window.
Pricing
Cost depends on the scale and complexity of the project – from a single property to a large-scale portfolio.
Our rate card is reviewed regularly, so we’re confident you won’t find better value elsewhere. If you’ve found a lower quote for comparable work, let us know – we’ll match or beat it.
Support
Energy efficiency, decarbonisation and building regulation can be genuinely complex.
We’ve worked hard to explain overheating topics in plain English, so non-experts get the information they need.
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Understanding TM52 Thermal Comfort Analysis: Your Questions Answered
What is CIBSE TM52, and why is it important for commercial buildings?
CIBSE TM52 is the UK industry-standard methodology for assessing overheating risk and thermal comfort in non-domestic, “free-running” (naturally ventilated or mixed-mode) buildings – such as offices, schools, care homes, and healthcare facilities.
Using Dynamic Thermal Simulation (DTS) modeling, TM52 predicts internal room temperatures based on local weather files, solar gains, and occupant activity profiles. It ensures spaces remain safe and comfortable during summer months without over-relying on carbon-intensive, expensive mechanical air conditioning.
How does CIBSE TM52 differ from CIBSE TM59 and Part O?
While all three standards evaluate overheating risk, they apply to different building sectors and regulatory pathways:
– CIBSE TM52: Designed specifically for non-domestic commercial assets (offices, educational buildings, community spaces and healthcare settings).
– CIBSE TM59: Designed specifically for residential developments (flats, student accommodation and communal residential schemes).
– Part O (Building Regulations): The statutory regulation enforcing overheating compliance for new residential developments in England and Wales.
If you are developing or managing an office, school, care home, or commercial space, CIBSE TM52 is the required framework for planning conditions and BREEAM compliance.
What are the three TM52 criteria a building must pass?
To achieve TM52 compliance, an occupied room zone must meet at least two out of the three statistical criteria set by CIBSE:
Criterion 1: Hours of Exceedance He – The number of hours that the internal temperature exceeds the upper adaptive threshold temperature must not exceed 3% of occupied hours during the summer season (May to September).
Criterion 2: Daily Weighted Exceedance We – Measures the severity of overheating on any single day, taking into account both the duration and how many degrees the internal temperature spikes above acceptable limits.
Criterion 3: Upper Limit Temperature Tmax – Sets an absolute maximum temperature limit that the room must never exceed to prevent acute heat stress and safety risks.
At what stage of a project should a TM52 overheating assessment be carried out?
Ideally, dynamic thermal modeling should be conducted during the early architectural design stage (RIBA Stages 2-3). Assessing overheating early allows passive design measures – such as building orientation, window opening areas, external shading (brise soleil) and solar-control glazing – to be integrated seamlessly before designs are frozen or submitted for planning.
However, TM52 analysis is also frequently deployed on existing commercial buildings experiencing severe comfort issues to diagnose structural heat gains and design targeted retrofit interventions.
What happens if our building fails the initial TM52 simulation?
We do not simply hand over a failing report. If your baseline design exceeds overheating thresholds, we use our Dynamic Thermal Simulation software to model cost-effective mitigation options.
We prioritise a passive-first hierarchy:
– Optimising glazing specification (balancing light daylighting with lower solar g-values).
– Re-evaluating window opening geometries and free-ventilation areas.
– Introducing night-time purge ventilation profiles.
– Integrating fixed or movable external shading (brise soleil, louvers or overhangs).
– Leveraging internal thermal mass.
Only if passive measures prove insufficient do we model mechanical cooling or hybrid ventilation systems, helping you minimise both upfront capital expenditure and long-term operational carbon costs.
Does a TM52 analysis support BREEAM certification and planning applications?
Yes. Local Planning Authorities (LPAs) and BREEAM assessors routinely mandate CIBSE TM52 dynamic thermal modeling. A TM52 report directly supports:
– BREEAM Credits: Fulfilling requirements under the Hea 04: Thermal Comfort issue (both for thermal modeling and climate change adaptation forecasting).
– Planning Conditions: Satisfying local planning requirements regarding climate resilience, passive design and summer thermal comfort.
What information do you need to prepare a TM52 model and quote?
To provide an accurate quote and build the dynamic simulation model, we typically require:
– Architectural floor plans, elevations and building sections (in PDF or CAD format).
– Proposed construction fabric specifications (wall, roof, floor U-values and glazing performance specs).
– Intended building usage (occupancy schedules, equipment power loads and staff density metrics).
– Proposed ventilation strategy (naturally ventilated windows, mechanical supply/extract rates or hybrid systems).
Need TM52: Thermal Comfort Analysis Services?
Our friendly team is ready to provide expert advice for your project. Whether you need a free consultation to discuss your options or a competitive quote for our TM52: Thermal Comfort Analysis services, we are here to help.
