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The challenge of overheating in buildings is on the rise due to changing climates and global energy uncertainties, making it increasingly difficult to control indoor climates.

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Overheating can stem from inappropriate design, poor management, or insufficient services. Design features aimed at reducing winter heating demand, like large south-facing windows, extensive insulation, low air permeability rates, and low thermal mass, may inadvertently lead to excessively high internal temperatures in the summer. To address this growing risk, CIBSE has introduced an adaptive methodology for assessing the anticipated level of thermal comfort within a building. This assessment can be conducted during the detailed design phase using a Dynamic Simulation Model. CIBSE TM52 establishes three compliance criteria to guide this assessment process.

Understanding and implementing these criteria are vital steps in addressing the challenge of overheating in buildings. Focus 360 Energy is here to support and guide you through the TM52 guidance and assess your project’s risk of overheating.

What Determines TM52 Non-Compliance?

Criterion 1
Between May 1 and September 30, during the non-heating season, a building fails Criterion 1 if the temperature exceeds the threshold comfort temperature (Tmax) by 1K for more than 3% of the occupied hours. Tmax is determined by the outdoor running mean temperature.

Criterion 2
This criterion focuses on a daily limit for acceptability rather than frequency. The cumulative value, obtained by multiplying the number of degrees by which the temperature exceeds Tmax by at least 1K for each hour (or part-hour), should not exceed six-degree hours.

Criterion 3
Expressed as (Tmax + 4) °C, this criterion establishes an unacceptable level of overheating. If a building’s temperature surpasses this figure during the non-heating season, it fails Criterion 3.

More simply this can be stated as:

Criterion 1: Hours of Exceedance
Criterion 2: Daily Weighted Exceedance
Criterion 3: Upper Limit Temperature

Understanding these criteria is vital for assessing a building’s compliance with TM52 Guidance during the specified non-heating season.

Often coupled with:

BREEAM Assessment
SBEM Calculation - (New Build - Non-Domestic)
TM44 Air Con Inspection
TM54 - Operational Energy Performance
Environmental Noise Assessment
Noise Impact Assessments
Circular Economy Statement

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Thermal Comfort

Experiencing comfort within indoor spaces significantly influences one’s mood. Whether in office buildings or any environment, operating under optimal conditions enhances cognitive functions and overall productivity. Thermal comfort is not only a key factor in promoting well-being but also in safeguarding against potential health risks. Creating an environment that balances temperature effectively is crucial for a harmonious and conducive atmosphere.

Factors that can Impact Thermal Comfort
Various factors play a crucial role in determining thermal comfort, aiming to maintain a harmonious balance for occupants’ satisfaction with their surroundings. The key elements include:

Air Temperature
This is a fundamental aspect of thermal comfort, easily adjustable through passive and mechanical heating and cooling methods.

Mean Radiant Temperature
This represents the weighted average temperature of all surfaces in a room. When combined with air temperature, it defines the operative temperature, a vital component of thermal comfort.

Air Velocity
Also known as airflow, it measures the speed and direction of air movements. Sudden fluctuations in air velocity can lead to complaints about drafts.

This refers to the moisture content of the air. Balancing humidity levels is crucial, as excessive highs or lows can induce discomfort. High humidity impedes sweat evaporation, affecting the body’s cooling process.

Clothing Level
The insulation added to the human body contributes significantly. Higher clothing levels reduce heat loss through the skin and impact the perceived comfortable temperature.

Physical Activity Level
Also known as metabolic heat, it influences the amount of heat produced by the body, affecting the perception of a hot or cold environment.

Understanding and managing these factors are essential for creating an environment where occupants can experience optimal thermal comfort.

Circular Economy Statement

Why Choose Focus 360 Energy for TM52 Assessments?

Opting for Focus 360 Energy for your TM52 assessment brings together expertise, innovation, and a commitment to client satisfaction. Our team of seasoned professionals is well-versed in the intricacies of TM52 criteria, ensuring meticulous assessments that adhere to industry standards.

Utilising cutting-edge technology, we provide comprehensive insights into your building’s thermal performance, offering tailored solutions to optimise energy efficiency. Throughout the TM52 assessment process, we maintain a client-centric approach, fostering transparency and collaboration to address your unique needs. Beyond mere compliance, our assessments prioritise practical, cost-effective strategies, delivering long-term value through substantial energy savings.

Choose Focus 360 Energy for your TM52 assessment, and embark on a seamless journey towards enhanced energy efficiency, regulatory compliance, and a more sustainable future.

Get Expert Assistance for Commercial Thermal Comfort

Seize the opportunity for superior energy performance and compliance with a TM52 assessment from Focus 360 Energy.

Our seasoned professionals stand ready to guide you through a precise assessment process, offering innovative, tailored solutions for optimal energy efficiency. Experience transparency and collaboration at every step.

Act now and redefine your building’s energy efficiency with confidence. Contact Focus 360 Energy today to embark on a journey towards sustainability, savings, and regulatory compliance.

Frequently Asked Questions

What is a TM52 overheating assessment?

A TM52 overheating assessment evaluates a building’s risk of overheating during the non-heating season. It follows the criteria set by the Chartered Institution of Building Services Engineers (CIBSE) to assess thermal comfort levels within a building.

Why is a TM52 assessment important for my building?

As the challenge of overheating in buildings increases due to changing climates, a TM52 assessment helps you understand and mitigate the risk of overheating. It ensures that your building provides a comfortable and safe environment for occupants, enhancing their well-being and productivity.

When should I consider getting a TM52 assessment?

You should consider a TM52 assessment during the design phase of your building project. This allows you to implement design features that reduce the risk of overheating and ensure compliance with TM52 criteria.


How long does a TM52 assessment take?

he duration of a TM52 assessment depends on the complexity of the building and the data available. Typically, it can take a few days to conduct the assessment and prepare the report.

How can Focus 360 Energy help with my TM52 assessment?

Focus 360 Energy specializes in TM52 assessments, providing expertise, innovation, and a client-centric approach. Our team of professionals ensures meticulous assessments that adhere to industry standards, offering tailored solutions to optimize energy efficiency and thermal comfort in your building. Contact us today to get started with your TM52 assessment.

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