The government has published the draft version of Part L which comes into force next year. Here are five key points you need to know

Goldsmith St ©Tim Crocker small

Goldsmith Street in Norwich was built to Passivhaus standards which are close to the 2025 Future Homes Standard

Last week the government revealed draft regulations that control space heating, hot water and lighting energy use in new homes. Launched as the Future Homes Standard consultation in October 2019, it proposed banning fossil fuel-fired boilers in new homes from 2025 in England with a carbon emissions reduction of 75%-80% compared with current standards.

The Future Homes Standard included proposals for an interim step towards the 2025 target to help the industry adjust to it. That step was intended to take effect in 2020 but has been delayed because of the disruption caused by the coronavirus pandemic.

> From the archive: Future Home Standard digital supplement

The government has now set out details of the interim step that will take effect next year. The rules will be implemented through Part L of the Building Regulations, which controls energy use, with a draft version now available.

Below we outline the five key things you need to know about the Future Homes Standard and Part L for new homes.

  1. The October 2019 consultation proposed two potential carbon reduction targets for the interim 2020 date, a cut of 20% or 31% in emissions compared with 2013 Part L. The government has plumped for its preferred option, the 31% reduction. The finalised version of Part L will be published in December 2021 and will come into force from June 2022, which gives the industry six months to prepare for the changes.

  2. The current version of Part L stipulates that homes must be built to minimum fabric energy efficiency standards (FEES) to avoid housebuilders using onsite renewable energy source panels to offset high carbon emissions from badly insulated homes. The 2019 consultation proposed dropping the FEES to the dismay of many in the industry. The government has now relented and will keep the FEES as part of a fabric-first approach.
    The FEES includes U values of 0.18Wm2/K for walls, 0.11Wm2/K for roofs and 1.2Wm2/K or better for windows. Fabric air permeability must be lower than 5m3/m2/@pa which is twice as demanding as the current standard.

  3. The 2019 consultation proposed stopping councils from setting more rigorous local energy efficiency standards than those set out in Part L via the planning system. Housebuilders say this piecemeal approach is confusing and inefficient as they cannot adopt one standard across all their schemes.The government has decided that councils can continue to set local targets with a new approach to be adopted as part of the planning system reforms.

  4. The government has stuck to its guns by following through on the consultation proposal to scrap a loophole that has allowed housebuilders to continue building homes on large sites to old energy regulations despite newer, tougher standards taking effect. Called transitional arrangements, housebuilders have been able to build all the homes on a site to the version of Part L in force when they first started work.

    This means someone who buys a house on a development being built out over many years could unwittingly end up with a much less energy-efficient home than one built at the same time on another scheme. The transitional arrangements applying to the new Part L will apply to individual homes rather than the whole development and are limited to one year.

  5. The U values for building elements in the 2021 Part L are equivalent to or better than those proposed for the 2016 zero-carbon homes target which was abandoned. The targets for the 2025 Future Homes Standard are equivalent to or in some cases even tougher than those set out in the Passivhaus standard.

    The exception is airtightness, which will stay at 5m3/m2/@pa which is approximately five times worse than the Passivhaus requirement, probably because achieving the latter is very difficult.

    To put the carbon reductions into perspective, the target for a typical semi-detached home built to the 2025 Future Homes Standard is 3.6kg/CO2/m2/yr compared with 16kg/CO2/m2/yr for a home built to current standards and 11kg/CO2/m2/yr for 2021 Part L.