Changes to the Building Regulations came into force on 15 June 2022, covering ventilation, energy and overheating in new buildings1. The revisions to Parts F and L were worked on in parallel and cut carbon emissions by 30% in new homes and by 27% in non-domestic buildings, according to the Building Engineering Services Association (BESA)1. The new Part O requires all new residential buildings, including care homes, children's homes and student accommodation, to be designed to reduce overheating1.
For non-domestic buildings, the government introduced three performance metrics against which they will be measured: primary energy, a CO2 emissions target, and minimum standards for fabric and fixed building services1. BESA said the primary energy metric is designed to make the energy efficiency of each building a priority regardless of the heat source1. Heat emitters must also be designed to work with low temperature sources such as heat pumps, which BESA describes as making buildings "zero carbon ready" in preparation for the 2025 Future Homes Standard1.
On ventilation, CO2 monitors became compulsory and new standards apply to recirculating ventilation systems in offices1. Indoor air quality monitoring is now mandatory in offices, and all recirculating ventilation systems must be capable of switching to "full fresh air" mode when necessary to reduce the risk of disease transmission1. Bathroom extract systems must have an "always on" feature, and the guidance stipulates a recommended minimum air supply rate of 0.5 l/s.m²1. Improved filtration is also part of the Part F changes, with a more frequent requirement for HEPA filters in systems that provide outside air1.
BESA's Director of Technical, Graeme Fox, wrote that the changes could help the industry make buildings healthier and more comfortable while reducing their carbon footprint1.
"The government is bringing in three performance metrics today against which new non-domestic buildings will be measured: primary energy, a CO 2 emissions target, and minimum standards for fabric and fixed building services"
BESA said officials at the Department for Levelling Up, Housing and Communities told it that the new ventilation requirements were deliberately prescriptive to prepare the country for future pandemics, and that the overall strategy was for tighter fabric standards and air tightness with additional focus on systems that bring outside air into buildings1. Trickle ventilators are also recommended in non-domestic buildings1. BESA said mechanical ventilation is the most effective way of keeping relative humidity within the range of 40% to 60%, which it describes as ideal for a range of health reasons1.
Why it matters for households
The rules apply to new buildings rather than to work on existing homes, so they shape what a newly built home contains rather than what an older one has. For a household buying or moving into a new home, the changes mean the property should be built to tighter fabric and air tightness standards, with ventilation designed in rather than left to opening windows1. The compulsory CO2 monitors and the "always on" bathroom extract requirement mean ventilation is intended to run continuously, which has a bearing on both indoor air and running costs1. The requirement that heat emitters work with low temperature sources such as heat pumps matters for energy independence because it means a new home's heating system is designed around a lower flow temperature, which is the operating condition heat pumps need1. Part O's overheating requirement addresses summer comfort without relying on energy-intensive cooling1.
What happens next
BESA states that the changes are made in preparation for the 2025 Future Homes Standard1. No further dated steps have been reported.