Part O

An entirely new Approved Document was published in June 2021, thereby incorporating the traditionally overlooked design aspect of ‘summertime comfort’ into Building Regulations. With a changing climate, SRE believes this is a step in the right direction, especially for the design of homes.

Building Regulations Part ‘O’ has two routes to compliance – a simplified method in the form of an Excel sheet and a detailed dynamic modelling method largely based on the thermal comfort standard CIBSE TM59. The dynamic method would be the preferred route to demonstrate compliance for the simple reason that it provides greater flexibility to the design team and client to test all the design parameters that affects overheating for a particular design rather than just glazing area and free opening area for natural ventilation.

Currently, compliance with Part ‘O’ is only required for new build residential schemes, but with most of the UK’s future housing stock already built, SRE is expecting that in the next update to Part ‘O’, the regulations are extended to include for ‘change of use’ schemes.