The Government published its response to a call for evidence on Approved Document O, the part of the building regulations covering overheating, and announced a review of Part O. The publication came alongside the updated regulations for England that give effect to the new Future Homes and Buildings Standards (FHBS), according to the Chartered Institution of Building Services Engineers (CIBSE)1.
CIBSE said the regulatory changes, which include updates to Approved Documents L and F, are intended to reduce carbon emissions in new homes and non-domestic buildings by up to 75% compared with the 2013 standard, and that they will be introduced from 20271. The call for evidence on Approved Document O was launched at the end of 20241.
CIBSE said it supports the Government's commitment to mitigating overheating risk in buildings and homes through regulation, and welcomed the announcement of a review of Part O and how regulations can further align with CIBSE TM59, its design methodology for assessing overheating risk in homes1.
"CIBSE welcomes the long-awaited updated regulations for England that give effect to the new Future Homes and Buildings Standards (FHBS)"
CIBSE said its knowledge, guides and technical memoranda were referenced extensively in the consolidated responses to the initial consultation and in the Government's response, and that CIBSE was specifically referenced in the Minister's written ministerial statement in Parliament in connection with TM591. Other cited publications include the Domestic Building Services Panel's Domestic Heating Design Guide, Guide A (Environmental Design), TM23 on testing buildings for air leakage, CP1 Heat Networks Codes of Practice, TM39 on building energy metering, TM54 on evaluating operational energy use at the design stage, an energy benchmarking tool and the SLL Code for Lighting1.
The response document itself has not been reported in detail. CIBSE said it will publish its analysis of the technical implications in the coming days, including whether the changes meet the intent of delivering "zero carbon ready" buildings1. The specific content of the Government's response to the call for evidence, and the scope and timetable of the Part O review, have not been reported.
Why it matters for households
Approved Document O sets the overheating requirements that new homes in England must meet, so changes to it affect how new housing is designed for hot weather. The overheating and hot weather in UK homes guide explains how homes gain and lose heat and what the current rules require. The wider FHBS package sits within the Future Homes Standard, which sets the direction for new-build energy performance, and the carbon reduction expected under it is measured against the 2013 baseline. For a household, the practical link between overheating rules and energy independence is that how a home is kept cool in summer shapes whether it needs mechanical cooling, and mechanical cooling adds to electricity demand. Homes built to the updated standards from 2027 will be the ones affected first; existing homes are not covered by these changes as reported. The regulation and policy hub carries further coverage of building standards.
What happens next
The updated FHBS regulations, with the Approved Documents L and F updates, are to be introduced from 20271. CIBSE said it will publish its analysis of the technical implications in the coming days1. No date has been reported for the outcome of the Part O review.