Overheating guidance and tools for building designers - Revision history

Designing Buildings at 06:04, 4 July 2025

2025-07-04T06:04:39Z

← Older revision		Revision as of 06:04, 4 July 2025
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	= Introduction =		= Introduction =

−	Overheating is an element of building fabric control that will have an increasing importance as climate adaptation measures need to be balanced with climate mitigation measures. Its effects are ~~indirectly~~ impacted by fabric quality, design, layout and strategy as well as material choices and servicing, that can in turn impact energy use.	+	Overheating is an element of building fabric control that will have an increasing importance as climate adaptation measures need to be balanced with climate mitigation measures. Its effects are impacted by fabric quality, design, layout and strategy as well as material choices and servicing, that can in turn impact energy use.

−	Building Regulations Part O ~~2022~~ establishes simplified and more complex dynamic modelling routes to provide evidence that certain design criteria that reduce the risks of overheating have been met. Below is a brief overview of differing developing guidelines in the past that have led up to Part O.	+	Building Regulations Part O establishes simplified and more complex dynamic modelling routes to provide evidence that certain design criteria that reduce the risks of overheating have been met.
		+
		+	Below is a brief overview of differing developing guidelines in the past that have led up to Part O.

	= Adaptive comfort theory =		= Adaptive comfort theory =
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	BS 40102 is comprised of two parts: BS 40102-1:2023 covers Health and well-being and indoor environmental quality in buildings, whilst BS 40102-1:2023 addresses Thermal Comfort, Indoor Air Quality, and Overheating. Key aspects related to overheating include:		BS 40102 is comprised of two parts: BS 40102-1:2023 covers Health and well-being and indoor environmental quality in buildings, whilst BS 40102-1:2023 addresses Thermal Comfort, Indoor Air Quality, and Overheating. Key aspects related to overheating include:

−	* Health and Wellbeing:The standard ~~emphasizes~~ the link between building design and occupant health, including the impact of overheating on physical and mental wellbeing.	+	* Health and Wellbeing:The standard emphasises the link between building design and occupant health, including the impact of overheating on physical and mental wellbeing.
	* Indoor Environmental Quality (IEQ): the overall IEQ of a building, considering thermal comfort, air quality, and ventilation.		* Indoor Environmental Quality (IEQ): the overall IEQ of a building, considering thermal comfort, air quality, and ventilation.
	* Overheating Mitigation: Provides a best-practice approach to identifying and addressing overheating risks, including strategies for limiting solar gains and providing adequate ventilation.		* Overheating Mitigation: Provides a best-practice approach to identifying and addressing overheating risks, including strategies for limiting solar gains and providing adequate ventilation.
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	for more information visit: [https://www.cibse.org/weatherdatasets https://www.cibse.org/weatherdatasets]		for more information visit: [https://www.cibse.org/weatherdatasets https://www.cibse.org/weatherdatasets]

−	= Good Homes Alliance ~~overheting~~ and risk assessment tools =	+	= Good Homes Alliance overheating and risk assessment tools =

	The Good Homes Alliance published an overheating guidance and risk score sheet tool for new homes in July 2019 followed by the same for retrofit and existing homes in March 2022, these are tools for early stage assessment not detailed assessment, sitting between existing high-level guidance, more detailed calculations and modelling tools. These identify key factors contributing to overheating risks, and possible mitigation measures.		The Good Homes Alliance published an overheating guidance and risk score sheet tool for new homes in July 2019 followed by the same for retrofit and existing homes in March 2022, these are tools for early stage assessment not detailed assessment, sitting between existing high-level guidance, more detailed calculations and modelling tools. These identify key factors contributing to overheating risks, and possible mitigation measures.
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	= Shading for housing, a design guide =		= Shading for housing, a design guide =

−	A product section provides detailed information to help users to select the right product for a building’s shading needs. Each product page features a brief description, a table detailing its functionality, an in-situ product photograph, a ~~‘performanceweb’~~ visualising a product’s strengths and weaknesses and, where relevant, an architect’s comment on a product’s added value.	+	A product section provides detailed information to help users to select the right product for a building’s shading needs. Each product page features a brief description, a table detailing its functionality, an in-situ product photograph, a ‘performance web’ visualising a product’s strengths and weaknesses and, where relevant, an architect’s comment on a product’s added value.

	The guide also provides a short history of shading design, explores UK-specific design challenges and wraps up with best practice advice. The guidance is applicable to both new build and retrofit projects, and aimed at a range of stakeholders including architects, local authorities, planners, housing associations, developers, and policy makers.		The guide also provides a short history of shading design, explores UK-specific design challenges and wraps up with best practice advice. The guidance is applicable to both new build and retrofit projects, and aimed at a range of stakeholders including architects, local authorities, planners, housing associations, developers, and policy makers.

Editor at 22:22, 1 July 2025

2025-07-01T22:22:44Z

← Older revision		Revision as of 22:22, 1 July 2025
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	For more information visit: [https://www.cibse.org/knowledge-research/knowledge-portal/technical-memorandum-55-design-for-future-climate-case-studies-2014-pdf/ https://www.cibse.org/knowledge-research/knowledge-portal/technical-memorandum-55-design-for-future-climate-case-studies-2014-pdf/]		For more information visit: [https://www.cibse.org/knowledge-research/knowledge-portal/technical-memorandum-55-design-for-future-climate-case-studies-2014-pdf/ https://www.cibse.org/knowledge-research/knowledge-portal/technical-memorandum-55-design-for-future-climate-case-studies-2014-pdf/]

−	= TM59 Design methodology for the assessment of overheating risk in homes =	+	= CIBSE TM59 Design methodology for the assessment of overheating risk in homes =

	A 2017 publication assessing overheating risk in homes. A complex issue and not adequately assessed by building regulations. Indeed, it would be wrong to assume that a home that complies with building regulations that were designed to focus on energy conservation also gives sufficient assurance of avoidance of overheating. Hence the recommendation that comfort conditions are separately assessed if it is felt that there could be a risk.		A 2017 publication assessing overheating risk in homes. A complex issue and not adequately assessed by building regulations. Indeed, it would be wrong to assume that a home that complies with building regulations that were designed to focus on energy conservation also gives sufficient assurance of avoidance of overheating. Hence the recommendation that comfort conditions are separately assessed if it is felt that there could be a risk.

Editor at 22:04, 1 July 2025

2025-07-01T22:04:09Z

← Older revision		Revision as of 22:04, 1 July 2025
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	For more information visit: [https://www.iso.org/standard/37059.html https://www.iso.org/standard/37059.html]		For more information visit: [https://www.iso.org/standard/37059.html https://www.iso.org/standard/37059.html]
		+
		+	= Passivhaus trust: Avoiding summer overheating =
		+
		+	Guidelines for summer comfort in Passivhaus buildings and the PHT Summer overheating tool
		+
		+	Summer overheating is a growing concern for both new and existing buildings, especially as climate change intensifies. A UK study showed that all modelled new-build homes failed CIBSE TM59 overheating criteria. While the Passivhaus standard includes limits on internal temperatures exceeding 25°C, accurate modelling is essential, and current models often rely on outdated climate data. Key factors affecting overheating include occupant behaviour, occupancy levels, and assumptions around ventilation and shading. A four-stage assessment approach is recommended: design strategies, occupant constraints, risk indicators, and stress testing. Tools like the Good Homes Alliance risk assessment can help identify early-stage risks. Overheating results from an imbalance between heat gains and losses, with solar gain being a primary driver. Localised risks, such as poorly ventilated or west-facing rooms, may not be captured in average whole-building models, so Dynamic Simulation Modelling (DSM) using TM59/TM52 guidelines is advised for detailed assessment and to ensure design resilience under varying conditions.
		+
		+	For more information visit: [https://www.passivhaustrust.org.uk/UserFiles/File/Technical%20Papers/Avoiding%20summer%20overheating.pdf https://www.passivhaustrust.org.uk/UserFiles/File/Technical%20Papers/Avoiding%20summer%20overheating.pdf]

	= Shading for housing, a design guide =		= Shading for housing, a design guide =

Editor at 21:47, 1 July 2025

2025-07-01T21:47:09Z

← Older revision		Revision as of 21:47, 1 July 2025
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	For more information visit: [https://www.gov.uk/government/publications/overheating-approved-document-o https://www.gov.uk/government/publications/overheating-approved-document-o]		For more information visit: [https://www.gov.uk/government/publications/overheating-approved-document-o https://www.gov.uk/government/publications/overheating-approved-document-o]

−	= ~~BB101~~ =	+	= BB 101: Ventilation, thermal comfort and indoor air quality =

−	~~Schools introduced~~ the ~~use~~ of ~~three overheating criteria~~ in ~~BB101~~. The ~~duration of overheating~~, ~~when~~ indoor ~~temperature may rise above 28ºC but for no more than 120 hours per year. The severity of overheating; where the averaged difference between the internal temperature~~ and ~~the external temperature (Tint – Text) remains less than 5ºC per day. As well as an upper temperature limit of 32ºC, that should not be exceeded~~.	+	This document describes the factors that affect the indoor environment of schools, setting out the regulatory framework for ventilation in schools and gives recommended performance levels for compliance with UK regulations. The document also provides non-statutory guidance on how to design schools to achieve adequate performance for ventilation, indoor air quality and thermal comfort.

−	For more information visit: [https://www.gov.uk/government/publications/building-bulletin-101-ventilation-for-school-buildings https://www.gov.uk/government/publications/building-bulletin-101-ventilation-for-school-buildings]	+	Schools introduced the use of three overheating criteria in BB101: The duration of overheating, when indoor temperature may rise above 28ºC but for no more than 120 hours per year. The severity of overheating; where the averaged difference between the internal temperature and the external temperature (Tint – Text) remains less than 5ºC per day. As well as an upper temperature limit of 32ºC, that should not be exceeded.
		+
		+	For more information visit: [https://www.gov.uk/government/publications/building-bulletin-101-ventilation-for-school-buildings https://www.gov.uk/government/publications/building-bulletin-101-ventilation-for-school-buildings]. Supporting the document are five simple spreadsheets [https://www.gov.uk/government/publications/classvent-and-classcool-school-ventilation-design-tool BB101 Calculation Tools].

	= BS 40102 Part 2 Thermal Comfort, Indoor Air Quality, and Overheating =		= BS 40102 Part 2 Thermal Comfort, Indoor Air Quality, and Overheating =

Editor at 21:44, 1 July 2025

2025-07-01T21:44:38Z

← Older revision		Revision as of 21:44, 1 July 2025
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	For more information visit: [https://www.cibse.org/knowledge-research/knowledge-portal/technical-memorandum-55-design-for-future-climate-case-studies-2014-pdf/ https://www.cibse.org/knowledge-research/knowledge-portal/technical-memorandum-55-design-for-future-climate-case-studies-2014-pdf/]		For more information visit: [https://www.cibse.org/knowledge-research/knowledge-portal/technical-memorandum-55-design-for-future-climate-case-studies-2014-pdf/ https://www.cibse.org/knowledge-research/knowledge-portal/technical-memorandum-55-design-for-future-climate-case-studies-2014-pdf/]
		+
		+	= TM59 Design methodology for the assessment of overheating risk in homes =
		+
		+	A 2017 publication assessing overheating risk in homes. A complex issue and not adequately assessed by building regulations. Indeed, it would be wrong to assume that a home that complies with building regulations that were designed to focus on energy conservation also gives sufficient assurance of avoidance of overheating. Hence the recommendation that comfort conditions are separately assessed if it is felt that there could be a risk.
		+
		+	Many factors influence overheating in homes, including the intensity of heat gains, occupancy patterns, orientation, dwelling layout, shading strategy and ventilation method. Dynamic thermal modelling can be used to simulate the internal temperature conditions and will therefore help establish whether threshold conditions of discomfort will be reached. Given the complexity of the factors influencing overheating it is important that a standardised methodology is used to assess risk and hence the need for this technical memorandum. It can be applied to dwellings, care homes and student residences. Early analysis of overheating risk is recommended so that mitigation strategies can be reviewed in design proposals.
		+
		+	In summary, the application of this technical memorandum, by standardising the assessment methodology, should play a key role in limiting overheating risk in new and refurbished homes.
		+
		+	For more information visit: [https://www.cibse.org/knowledge-research/knowledge-portal/technical-memorandum-59-design-methodology-for-the-assessment-of-overheating-risk-in-homes/ https://www.cibse.org/knowledge-research/knowledge-portal/technical-memorandum-59-design-methodology-for-the-assessment-of-overheating-risk-in-homes/]

	= Climate modelling =		= Climate modelling =
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	For more information on retrofit visit: [https://kb.goodhomes.org.uk/tool/overheating-retrofit/ https://kb.goodhomes.org.uk/tool/overheating-retrofit/]		For more information on retrofit visit: [https://kb.goodhomes.org.uk/tool/overheating-retrofit/ https://kb.goodhomes.org.uk/tool/overheating-retrofit/]
		+
		+	= Guidance on preventing overheating in the home =
		+
		+	This guidance back by the government from 2015 outlines precautions people can take to prevent homes from overheating. Energy efficiency improvements help make homes warm and cosy in the winter and keep energy bills down. They also help us to reduce our carbon emissions and tackle climate change. Some energy efficiency improvements can also make homes hotter in the summer months. However, if these improvements are designed and installed correctly, the impact on summertime temperatures within homes can be greatly reduced. Future climate change is expected to increase outdoor temperatures and we all need to take steps to adapt to a changing climate. Undertaking energy efficiency improvements provides a great opportunity to not only make improvements to the standard of homes, but to also make them more resilient to climate change. This document can help to identify the homes which may be most at risk of overheating and gives details of measures which, if implemented at the same time as energy efficiency improvements, can significantly reduce the risk of overheating, and the potential use of energy for cooling.
		+
		+	For direct download visit: [https://www.cibse.org/media/jvohyswt/decc-overheating-guidance-document-19jun2015.pdf https://www.cibse.org/media/jvohyswt/decc-overheating-guidance-document-19jun2015.pdf]

	= ISO 13792 Thermal performance of buildings - Calculation of internal temperatures of a room in summer without mechanical cooling - Simplified methods =		= ISO 13792 Thermal performance of buildings - Calculation of internal temperatures of a room in summer without mechanical cooling - Simplified methods =

Editor at 21:37, 1 July 2025

2025-07-01T21:37:55Z

Show changes

Editor: moved Overheating guidance for buildings to Overheating guidance and tools for building designers

2025-07-01T21:00:14Z

moved Overheating guidance for buildings to Overheating guidance and tools for building designers

← Older revision

Revision as of 21:00, 1 July 2025

Editor at 20:57, 1 July 2025

2025-07-01T20:57:36Z

← Older revision		Revision as of 20:57, 1 July 2025
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		+	[[File:Thermometer and tools 1000.jpg]]
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	= Introduction =		= Introduction =

Editor at 20:40, 1 July 2025

2025-07-01T20:40:59Z

← Older revision		Revision as of 20:40, 1 July 2025
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	For more information visit: [https://www.zerocarbonhub.org/sites/default/files/resources/reports/ZCH-OverheatingEvidenceReview-Definitions.pdf https://www.zerocarbonhub.org/sites/default/files/resources/reports/ZCH-OverheatingEvidenceReview-Definitions.pdf]		For more information visit: [https://www.zerocarbonhub.org/sites/default/files/resources/reports/ZCH-OverheatingEvidenceReview-Definitions.pdf https://www.zerocarbonhub.org/sites/default/files/resources/reports/ZCH-OverheatingEvidenceReview-Definitions.pdf]

−	= Good Homes Alliance risk ~~assessments~~ =	+	= Good Homes Alliance overheting and risk assessment tools =

	The Good Homes Alliance published an overheating guidance and risk score sheet tool for new homes in July 2019 followed by the same for retrofit and existing homes in March 2022, these are tools for early stage assessment not detailed assessment, sitting between existing high-level guidance, more detailed calculations and modelling tools. These identify key factors contributing to overheating risks, and possible mitigation measures.		The Good Homes Alliance published an overheating guidance and risk score sheet tool for new homes in July 2019 followed by the same for retrofit and existing homes in March 2022, these are tools for early stage assessment not detailed assessment, sitting between existing high-level guidance, more detailed calculations and modelling tools. These identify key factors contributing to overheating risks, and possible mitigation measures.

−	For more information visit: [https://goodhomes.org.uk/overheating-in-new-homes https://goodhomes.org.uk/overheating-in-new-homes]	+	For more information on new builds visit: [https://goodhomes.org.uk/overheating-in-new-homes https://goodhomes.org.uk/overheating-in-new-homes]
		+
		+	For more information on retrofit visit: [https://kb.goodhomes.org.uk/tool/overheating-retrofit/ https://kb.goodhomes.org.uk/tool/overheating-retrofit/]

	= Building regulations approved document O =		= Building regulations approved document O =

Editor at 20:37, 1 July 2025

2025-07-01T20:37:08Z

← Older revision		Revision as of 20:37, 1 July 2025
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	For more information visit: [https://www.gov.uk/government/publications/overheating-approved-document-o https://www.gov.uk/government/publications/overheating-approved-document-o]		For more information visit: [https://www.gov.uk/government/publications/overheating-approved-document-o https://www.gov.uk/government/publications/overheating-approved-document-o]
		+
		+	= Shading for housing, a design guide =
		+
		+	A product section provides detailed information to help users to select the right product for a building’s shading needs. Each product page features a brief description, a table detailing its functionality, an in-situ product photograph, a ‘performanceweb’ visualising a product’s strengths and weaknesses and, where relevant, an architect’s comment on a product’s added value.
		+
		+	The guide also provides a short history of shading design, explores UK-specific design challenges and wraps up with best practice advice. The guidance is applicable to both new build and retrofit projects, and aimed at a range of stakeholders including architects, local authorities, planners, housing associations, developers, and policy makers.
		+
		+	For more information and to download the guide, visit: [https://kb.goodhomes.org.uk/guidance/shading-for-housing/ https://kb.goodhomes.org.uk/guidance/shading-for-housing/].

	= Related articles on Designing Buildings =		= Related articles on Designing Buildings =