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Part L and The Future Homes Standard

26th January 2024

An important consultation on the Future Homes Standard

Late last year, the government published its long-awaited consultation on The Future Homes and Buildings Standards.

The consultation applies to new building regulations for England only. The Future Homes Standard, and its non-domestic counterpart the Future Buildings Standard, are set in regulations to come into force in England in 2025. Scotland, Wales and Northern Ireland have devolved powers to implement similar standards and regulations as and when they wish to.

The new standards set the performance requirements at a level which ensures new homes and non-domestic buildings have high fabric standards, use low-carbon heating and are ‘zero-carbon ready’ (meaning no further work will be needed for them to have zero carbon emissions once the electricity grid has fully decarbonised).

The consultation includes options for what a ‘Future Homes Standard’ new home should look like, and proposals for a new badge for housebuilders to use in promoting new homes which are proven to be ‘zero-carbon ready’.

Importantly, the consultation does not seek to change the minimum building fabric standards for homes compared to the Part L 2021 standards, as the government feels Part L is already good enough (more on Part L below).

But there are improved standards in the pipeline for ‘material change of use’ (conversion) projects, and the proposed new regulations do increase standards for fixed building services and on-site electricity generation. These are likely to have important implications for the design and construction of trussed rafter roofs.

For example, the increasing airtightness and insulation standards are driving an increase in use of MVHR systems for ventilation (mechanical ventilation with heat recovery), which often needs equipment stored in the roof space.

Ideally, MVHR units should not themselves be placed in the loft – access is required every 3-6 months to change the intake and extract filters inside the unit, so they’re better placed in a utility or plant room or cupboard. But some housebuilders do choose to locate such equipment in the loft, which means the roof design needs to allow for the weight of this, plus very good access with walkway and floorboards over the insulation. MVHR intake and exhaust ductwork is also very likely to run through the roof space, so this will also impact on design and insulation.

There may also be other equipment in the roof linked to the increased use of renewable technologies in new homes, including battery storage for PV units or other M&E equipment.

If you believe  TRA should respond  to the Future Homes Standard consultation on behalf of members  please send your detailed comments to t the TRA Technical Committee via

Alternatively you can also respond directly here:

The deadline for responses is 6 March 2024.

A reminder about Part L 2021

Most TRA members will be familiar with the Approved Document Part L changes introduced at the end of 2021 and made mandatory for all new dwellings in England from June last year (with similar standards now in Scotland, Wales and Northern Ireland).

These building regulations are part of a wider effort to reduce the environmental impact of buildings and help the UK achieve its goal of net-zero carbon emissions by 2050.

The main points from Part L 2021 for new and existing homes are:

  • New carbon emissions targets – All new homes must produce at least 31% less carbon emissions (27% less for new non-domestic builds).
  • New minimum energy efficiency standards – Higher standards for insulation, heating, lighting, and ventilation systems, including new Notional Dwelling U-values for roofs, walls and floors, to minimise energy consumption and carbon emissions:

New builds:

Roofs: 0.11 W/m²K

Walls: 0.18 W/m²K

Floors: 0.13 W/m²K


New elements in existing dwellings:

Roofs: 0.15 W/m²K

Walls: 0.18 W/m²K

Floors: 0.18 W/m²K


Existing elements in existing dwellings:

Roofs: 0.16 W/m²K

Walls: 0.30 W/m²K

Floors: 0.25 W/m²K

  • Increased focus on ‘thermal bridging’ – To improve accuracy, thermal bridging calculations now need precise PSI Value data. This will help calculate the heat loss through building materials correctly and reduce energy costs and carbon emissions. Using generic PSI values, which were previously allowed, will now result in fines.
  • Mandatory photographic evidence – It is now compulsory to provide photographic evidence as proof of compliance. Such evidence must be taken throughout the appropriate stages of construction when each detail is completed.
  • New SAP calculation software – SAP 10 incorporates current carbon emission factors, to provide a more accurate assessment of climate change effects. But this will probably be the last time you’ll see SAP used as a calculation methodology, as the Future Homes Standard consultation includes a proposal for a completely different methodology from 2025 – the Home Energy Model (HEM). One to watch.
  • It is important to be aware that, within the Future Homes Standard consultation for domestic buildings, where any Notional Dwellings are used without change, the dwellings constructed are expected to meet the performance requirements. But for any change (regardless of how minor), designers will need to use the new HEM software to calculate the impact of that change. For designers and assessors, it will be difficult to assess the full impact of what is being proposed without doing this.

The updated Part L Building Regulations offer a chance to adopt innovative and sustainable methods in the construction sector. There are some challenges to overcome, but by staying informed, TRA members will be ready to meet the standards.

Please contact the TRA Technical Committee for further information about how the TRA can assist you with Part L compliance.

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