Hea 04 - Thermal comfort - BREEAM Knowledge Base

Adaptability for a projected climate change scenario – Winter conditions - KBCN1715

Where future climate change scenario projections in winter indicates a higher temperature and, therefore, more thermally comfortable climate compared to the current winter temperatures, it can be assumed that the winter conditions within the climate change scenario are met based on the thermal modelling of current winter conditions. Justification must be provided for each project confirming that the future winter conditions will be met with the current heating system. In a warming climate the heating system needs to be sized for the beginning of its lifespan, whereas the cooling systems need to be sized for the end of their life span (Ref: CIBSE TM55: 2014)

Approach to thermal model when using BMS - KBCN0169

Where there are smart systems such as BMS in place, modelling must consider normal operating conditions, with the heating and cooling system in operation regardless of the control strategy. In order for the design team to size the heating/cooling plant, they will carry out modelling to calculate the heat/cold loss throughout the year. Results of these calculations must be submitted, with the heating/cooling plant specification which would demonstrate that the building has been designed to ensure internal winter/summer temperatures will not drop below an acceptable level, and that in effect the winter TOR is zero.

14 Apr 2023 Applicability to UK NC2018 and UK/Int V6 confirmed

Assessing industrial spaces – exemptions - KBCN0734

The thermal comfort criteria do not apply to the operational or storage areas typically found in industrial assets or other similar asset types. The criteria is still be applied to the other parts of the asset as appropriate. Operational and storage areas often have function-related thermal requirements determined by operational or storage needs. These functional requirements override the needs of any occupants.

17-Jan-2024 - Scheme applicability updated.
03-Nov-2020 - Issue 2.0 of UK RFO technical manual updated with new CN detailing the above.

Assessing thermal comfort – Residential buildings - KBCN1408

CIBSE TM59 can be used to demonstrate compliance with the thermal comfort requirements for residential and multi-residential buildings (long-term stay), instead of ISO 7730:2005. This is to recognise the most up to date methodology relating to the assessment of homes

26 Jan 2025 - Updated to apply to multi-residential buildings (long-term stay) and scheme applicability extended to account for this.

Weather files – 2020s, 2030s and 2050s - KBCN0842

Timescale The weather files for each decade cover a 30-year climatic period around that decade. For example, 2020s weather files cover the period 2010 to 2040. 2020s are in the middle of the three decades (10s / 20s / 30s). NC - 2020s and 2050s New Construction projects assessed under the relevant standards should continue to use the 2020 weather files for mechanical ventilation, and the 2050 weather files for natural ventilation. CIBSE weather files are available here: CIBSE Weather Data RFO - 2030s and beyond When published, the original intent for RFO projects was for future thermal comfort to be based on projected climate change 15 years after completion.

For projects completed between 2015 and 2025, the 2030s data may still be used. This can be found here: Prometheus weather data.
For projects completing after 2025, use CIBSE weather data covering the 2040s (included within the 2050s data): CIBSE Weather Data.

08-Jan-2024 - Added clarification on RFO 2030s data.
18-Dec-2024 - Merged with KBCN000006. Prometheus link updated. Title updated.
04-Jul-2024 - Clarified that 2020 and 2050 weather files are still valid for the applicable standards and guidance applied to all relevant UK standards. Applicability to international standards removed and link to CIBSE weather data added.

Weather files – 50th percentile - KBCN0117

For the thermal simulation of climate change environments, where this not specified in the manuals, the 50th percentile weather file is used in all cases. This applies also to the use of any alternative weather files or formats which are not listed in the manual. See KBCN1182.

18-Dec-2024 - Title updated for clarity. Scheme applicability updated. Link to KBCN1182 added.

Weather files – alternative format or location - KBCN1182

If they achieve the aim of the credit, alternative weather file formats not listed in the manuals can be used instead of those referenced in the manual. Format - current climate The alternative weather files must include same variables as the specified weather files for each hour of the year e.g.: - Dry bulb & wet bulb temperature, - Wind speed & direction, - Solar altitude & azimuth, - Cloud cover etc. For example, TMY (Typical Meteorological Year) is an accepted alternative format for BREEAM, meeting the requirements above. The assessor or design team must verify this and ensure that meeting the BREEAM criteria does not become easier by using the alternative weather file. Format - projected climate These alternative files must be based on climate projections with equal or higher temperatures than those specified in the relevant criteria, setting an equally or more robust standard for overheating. Where there are no suitable weather files available for projected climate change, use any one of the following:

To modify weather data for existing climates into the relevant future climate change scenarios required in the criteria. Alternative location Where the weather file for the nearest location for the project is not representative of the actual location’s climatic conditions, the project team can use the weather file from another nearby location which is more representative. This can take account of the climatic influences of altitude, prevailing wind, proximity to climate-moderating features, or heat island effect.

19-May-2025 - Added example alternative format. Added links to future climate change resources.
18-Dec-2024 - Merged with KBCN1013. Scheme applicability updated.

New Construction / UK / V6 / 02 Health and Wellbeing /

Hea 04 - Thermal comfort