Proposed changes to new building energy regulations could be the last

The government is proposing that all new buildings are net zero ready from 2025, according to a consultation on future building energy standards published yesterday.

The government said that once introduced, the proposals mean no further work will be needed for new buildings to meet the UK’s 2050 net zero target.

The consultation, called the Future Homes and Buildings Standards, will apply to new homes and non-domestic buildings and sets out technical proposals for changes to Part L of the building regulations which would come into force in 2025.

Proposals to improve the energy performance of new buildings focus on improving standards for building services. These include banning gas boilers in favour of air source heat pumps for domestic and non-domestic buildings.

Building fabric energy performance standards will remain unchanged apart from higher airtightness standards as the government says these are already good enough and that improving the efficiency of building services is more cost effective. Gas boilers will be banned with the idea air source heat pumps become the default for cooling and heating.

The proposals don’t apply to the upfront embodied carbon emissions generated from making the products and materials used to construct buildings although the government said it intended to consult on an approach to measuring and reducing embodied carbon in new buildings in ‘due course.’

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The consultation proposes tougher standards for lighting and ventilation fan efficiency for new homes and includes two options for enhanced building services. The first proposes that new homes are fitted with PV panels, wastewater heat recovery systems and decentralized mechanical extract and must achieve an airtightness standard of 4m3/m2hr@50Pa. The current standard is 8m3/m2hr@50Pa.

Option two requires an airtightness standard of 5m3/m2hr@50Pa only. The government said this would represent a 75% reduction in carbon emissions compared to 2013 building regulations. It said this would cost housebuilders an additional 1% for a semi-detached home, and 4% for the first option for a semi-detached home.

The government is also proposing to replace the standard assessment procedure (SAP) which is used for calculating compliance with Part L. It has launched a separate consultation on the Home Energy Model which will be used for calculating compliance and is said to be more accurate than SAP. It will be capable of simulating energy performance for each half-hour of the day rather than on a monthly basis for SAP. The government said the Home Energy Model will be used to produce EPC certification with proposals published in a few months.

There will also be tougher standards for the efficiency of lighting and heat recovery with new standards for heat pump controls. There will also be new minimum energy efficiency standards for lifts and escalators which are currently unregulated.

The government proposes dividing building types into top lit and side lit; the former will include warehouses and sports halls, the latter includes offices, schools and hotels. It proposes two options for the percentage of PV fitted to new buildings. The governments preferred option is for 40% of all building types foundation areas to be covered by PV. The second option proposes this is reduced to 20% for side lit buildings. The cost uplift is estimated to be an additional 5.8% for a retail warehouse, 2.1% for a deep plan office and 3.1% for a school if both were fitted with 40% PV. There will be no change to the metrics used for calculating compliance for all building types.

The government also wants to toughen up energy efficiency standards for buildings that have undergone a material change of use such as offices converted into homes. Standards for buildings that have undergone a material change of use are much lower than new buildings even though homes in a converted office can be sold as new build. The government is seeking views on what the new standards could be.

Stuart Fairlie, the managing director of Elmhurst Energy, the UK’s largest accreditation scheme for energy assessors welcomed the proposals. He said: “We now have complete clarity about the best low carbon heating systems for new homes from 2025. It’s heat pumps all the way and this is the right solution. The standard has dismissed fossil fuels, a step bolder even than the COP 28 deal this week.”

The BRE, who led on the development of the Home Energy Model, also welcomed the proposals. Gillian Charlesworth, its chief executive said: “As uptake of green technologies increases, an effective assessment methodology which accounts for these changes will be imperative as the Government looks to secure buy-in from homeowners, housebuilders, and the retrofit industry on the net zero transition and achieve its targets in this area.”