Hea 05 - Thermal comfort

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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Flexibility of acoustic requirements for naturally ventilated buildings - KBCN0219

When the Design Capability Supply Rate of 8 l/s per person is provided by natural ventilation, the design can achieve the BB93 performance standards for the indoor ambient noise levels in Table 1.1 of BB93 then the requirements can be increased by 5 dB LAeq,30min. This approach can be followed where BB93 is applicable.

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Thermal comfort – Time-critical requirement - KBCN1801

The requirement for the full dynamic thermal analysis at detailed design stage, is set as this is the optimal stage to achieve the required sustainability outcome. When undertaken at a later stage, opportunities may be missed, options reduced or costs may become prohibitive. therefore the stipulated timeframes for such actions must generally be adhered to. However, if, due to specific circumstances or a non-standard the procurement route being used, the assessor can demonstrate that the aim of the criteria can still be fully met, despite the project having moved into a subsequent work stage, this will be accepted by BREEAM. In such cases, the assessor must justify and demonstrate that the ability to fully meet the aim of the criterion has not been compromised.

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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.

  NOTE: For BREEAM standards published before September 2025, the 2016 CIBSE Weather Data may still be used.  

15-Oct-2025 - Note added to clarify version requirements for 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.
19-Sept-2025 - Applicability to RFO projects added.

 

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