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Hea 03 - Thermal Comfort

Information correct as of 19thJune 2021. Please see kb.breeam.com for the latest compliance information.

Air-conditioned spaces - KBCN00035

Air-conditioned spaces are assessed to ensure appropriate thermal comfort levels are achieved. Cooling capacity should be sufficient to comply with the requirements of CIBSE Guide A, however providing sufficient space to install additional capacity to meet the requirements at a later date in line with projected climate change scenarios is also acceptable. In addition, if it can be demonstrated that the air-conditioning system can achieve the thermal comfort criteria in accordance with CIBSE Guide A, Table 1.5, thermal modelling does not need to be carried out. The “time out of range” (TOR) metric should be reported as 0%.  

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.  

Assessing industrial spaces – exemptions - KBCN0734

The thermal comfort criteria are not applicable to the operational or storage areas typically found in industrial buildings. The criteria should still be applied to the other parts of the building as appropriate. Operational and storage areas often have function related thermal requirements determined by the needs of the operation or the items being stored. These functional requirements supersede the needs of the occupants.
Technical manual to be updated accordingly in the next re-issue of each manual

03.11.2020 Issue 2.0 of UK RFO technical manual updated with new CN detailing the above.

Assessing thermal comfort in residential buildings - KBCN1408

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

Definition of concourse - KBCN0386

A concourse is an open area within or in front of a public building which is used primarily for circulation, short term waiting, or incidental interaction, analogous to the concourse of a train station. It should not be considered occupied space.  

Natural ventilation – use of CIBSE TM52 - KBCN0935

For a naturally ventilated building, it is acceptable for the thermal comfort limits and calculation methodology in CIBSE TM52: The Limits of Thermal Comfort: Avoiding Overheating in European Buildings to be used in place of ISO 7730:2005. BREEAM recognises that adaptive comfort models can provide more appropriate thermal comfort limits for naturally ventilated buildings.

Occupant control – BMS and degree of control - KBCN0175

A Building Management System controlled set point with local override controls limited to a set range would satisfy the occupant control requirement so long as the temperature range available to building users is confirmed as appropriate for the building type and user profile.

Occupant control – spaces requiring user controls - KBCN0170

The following guidance is intended to clarify the types of area for which user controls are required or would be considered beneficial. Please refer to the specific requirements of the applicable BREEAM Scheme to interpret this guidance appropriately. User controls which allow independent adjustment of heating/cooling systems within the building are required/considered beneficial in the following areas: User controls which allow independent adjustment of heating/cooling systems within the building are not required in the following areas: Please note that zoning is required in all areas of the building where specified in the assessment criteria for this issue.   User controls are required/considered beneficial in spaces which are owned, shared or temporarily owned by individual building occupants. User controls are not required in occasionally visited spaces or spaces where individual occupants are not expected to have control over the thermal conditions. 

Reporting PPD and PMV Figures - KBCN0867

The individual carrying out the modelling should be able to provide values for both the PMV and PPD for the building. The PMV and PPD values need to be reported, in the scoring & reporting tool, for data recording purposes. The values to report are the observed range of values for PMV and PPD across all occupied areas across all the hours when these are expected to be occupied (enter the minimum and maximum for each i.e. PMV = 0.2 - 0.5, PPD = 10 - 15%). However, if compliance with the thermal comfort criteria is demonstrated without using a full dynamic thermal analysis software package and via a less complex system, which does not generate the required PMV/PPD metrics, these do not have to be provided.

Thermal comfort – Changing rooms - KBCN1133

Whilst thermal comfort in changing rooms may be considered as significant, such spaces are, generally, outside the scope of this Issue, as they would not fall within the definition of an 'occupied space'.
17/06/2019 - This supersedes the advice previously provided in this KBCN, which was published in error on 13/06/2018

Thermal modelling for large scale projects - KBCN1171

In cases where the scale of the project makes it unfeasible to provide thermal modelling for every space, it is acceptable to demonstrate compliance with a representative sample of floors or rooms, ensuring any worst case scenarios are included.
Information correct as of 19thJune 2021. Please see kb.breeam.com for the latest compliance information.