Hea 03 - Thermal Comfort

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%.  

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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

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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.

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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.  

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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.

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Occupant control – spaces requiring user controls - KBCN0170

This guidance is intended to clarify the types of area for which user controls are required or would be considered beneficial. Zoning is required in all areas of the asset where specified in the assessment criteria. Please refer to the specific requirements of the applicable BREEAM standard to interpret this guidance appropriately. User controls required Spaces where users are expected to have independent control over their environment.

• Owned spaces: small rooms for a few people. For instance, cellular offices, owned spaces in residential assets.
• Temporarily owned spaces: where occupants expect to operate the environmental controls while they are there. For instance, meeting rooms and hotel bedrooms.
• Shared spaces. For instance, multi-occupied areas such as open-plan offices or workshops.

User controls not required Spaces where users are not expected to have independent control over their environment.

• Managed spaces: where environmental control is expected to be centrally managed. For instance, atria, circulation areas, concourses, entrance halls, function halls, restaurants, libraries, and shops.
• Occasionally visited spaces. For instance, storerooms, bookstacks in libraries, aisles of warehouses, toilets.

14-Dec-2022 - KBCN applicability updated to include BIU. Wording clarified, and amended for compatibility with BIU criteria.

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Performance standards of BB101 - KBCN0249

The Compliance Note ‘appropriate industry standards and criteria for schools’ must be followed, which states that Requirement a) of BB101 must be improved upon. Therefore if this improvement is achieved for performance standard a) then it is sufficient, for BREEAM compliance, for EITHER b) or c) of BB101 to be achieved.

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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

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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.

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TOR for schools - KBCN0172

The 'time out of range' (TOR) requirement is satisfied when a significantly better performance is justified to have been achieved in comparison to the appropriate industry standard. Where there is no appropriate industry standard available or TOR recommendation, the building services engineer needs to confirm the TOR is acceptable for the specific building. Where there is a reference to 60 hours TOR in relation to Building Bulletin 101 recommendations, this is purely for illustration and not a compliance requirement.    

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