CIBSE TM52 Thermal Comfort Analysis
The problem of overheating in buildings is a growing issue. Improvements in build design aimed at minimising winter heating demand can mean that during summer months buildings run the risk of overheating. These improvements include better insulation, large south-facing windows and low air permeability rates.
To tackle this problem, CIBSE have created a design-stage methodology that can assess the predicted level of thermal comfort within a building.
CIBSE TM52, as this methodology is called, sets three criteria for compliance: (1) Hours of Exceedance, (2) Daily Weighted Exceedance, (3) Upper Limit Temperature. Failure to comply with two or more of these is regarded as a fail. A failure means that the proposed building is seen as carrying an unacceptable risk of overheating.
Along with a detailed analysis of your building, using the CIBSE TM52 thermal comfort metric, our consultants can also provide you with support throughout the process, ensuring that you have everything required to achieve compliance.
Criterion 1
During the non-heating season, which covers the period 1 May to 30 September, Criterion 1 caps at 3 per cent on the number of occupied hours that the temperature within a building is allowed to go beyond the threshold comfort temperature (Tmax) by 1K. Tmax is a function of the outdoor running-mean temperature.
Criterion 2
This criterion sets a daily limit for acceptability, rather than frequency. If each hour (or part-hour) in which the temperature exceeds Tmax by at least 1K is multiplied by the number of degrees by which it is exceeded, this amount should not be greater than six degree-hours.
Criterion 3
This provides a figure, expressed as (Tmax + 4) °C, beyond which a buildings temperature cannot exceed. This is a level of overheating that is deemed unacceptable. The level is assessed during the non-heating season.
What causes overheating?
The location of the building. For example, urban areas tend to generate more external heat than less built-up areas.
The size and orientation of windows and rooflights, and level of solar control glazing can lead to high levels of solar gains entering the building.
The degree of shade provided both externally and internally.
Heat derived from occupants, lighting and equipment.
The level of natural or mechanical ventilation provided.
Air Conditioning
CIBSE TM52 only applies to buildings where the peak internal temperature is not controlled by air-conditioning. For buildings fitted with comfort cooling, Fanger can be used as the methodology for assessing thermal comfort.
BREEAM Hea 04
Thermal comfort analysis can be used to gain vital credits that will contribute to the BREEAM rating for the building. Three credits are available: one for carrying out the thermal analysis, one for assessing the building under projected climate change scenarios, and one for thermal zoning and controls.
Building Bulletin 101
For schools, the revised version of Building Bulletin 101 (BB101): Guidelines on ventilation, thermal comfort and indoor air quality was introduced in August 2018.
The new version introduced the idea of adaptive thermal comfort, setting a temperature threshold that changes depending on external conditions (in the absence of mechanical cooling).
Mirroring CIBSE TM52, there are three criteria to assess when overheating is likely to be an issue: total hours of exceedance, daily weighted exceedance, upper limit temperature. Criterion 1 is mandatory and must be less than 40 hours. Criterion 2 and Criterion 3 are not mandatory, but the relevant authorities should be made of infractions should they occur.
Why choose Achieve Green?
Fast, competitive and accurate CIBSE TM52 thermal comfort analysis.
The thermal comfort reports we provide can be utilised to assist building design, gain credits under BREEAM, provide support in Planning applications, and to satisfy industry requirements.
A complete advice and support service, comprehensive enough to make sure that you achieve compliance in the most cost-effective and practical way possible.
COMPETITIVE
Fast and accurate assessments at a competitive price.
EXPERIENCED
Comprehensive advice and support to ensure you arrive at the most economic and feasible solution to achieve compliance.
QUALIFIED
You can take comfort that the certificates we provide will be accepted as evidence for Building Regulations sign-off.
VALUE
Best quality advice, at a price that offers real value for money.
Testimonials
We are an RIBA Chartered Architectural Practice based on the South Coast, and have used the services of the Achieve Green team in Tunbridge Wells on countless projects over many years, mainly for the preparation of SAP calculations but also energy statements and air pressure testing across a broad range of projects. They have offered us invaluable practical advice on more complex projects to ensure compliance with the ever evolving statutory standards and we have always found them to provide a prompt, efficient, friendly and cost effective service and would not hesitate to recommend them.
Lightbox Architecture Limited
We have found the Achieve Green team to be highly experienced, specialised and competent. Advice is constructive and their approach to projects is strategic, ensuring the most effective solutions are taken forward. The team has a comprehensive understanding of planning requirements and appreciates how these translate into technical and on-site delivery. We highly recommend the team and look forward to working with them on forthcoming projects.
Kitewood Estates Ltd
As a business we have been involved with Achieve Green for a number of years. Their proactive involvement in our projects from design through to completion has enabled us to continually improve the energy efficiency of all our homes. The prompt and efficient service has meant they have become an integral part of our design team.
Panfile Ltd
I have been working with Jonathan and his Achieve Green team in Tunbridge Wells since 2011 on a range of projects from Schools, new build housing to straightforward extensions. They are very knowledgeable and efficient and have provided invaluable input to projects over the years ensuring that as a designer I can put forward the most cost effective solutions to complying with Part L.I always recommend Jonathan if ever anybody is in need of SAP and compliance testing services.
Bradbury Design Ltd