Part L changes for the UK – 2021/22

After several consultations, the new thermal requirements for building fabric for each of the UK nations have now been released.

We have summarised the changes in our updated Guidance Note, which we are making available to all: CGN 17-5 Thermal requirements for doors, windows, roof windows, rooflights and curtain walling – comparison charts for the UK. [Note: issue 05, with the publication of AD L2 in Wales with some minor amends from issues 03 and 04.]

Detailed Guidance Notes for each of the devolved nations are in preparation, and these will be available to CAB members.

Alongside the changes to Part L (Conservation of fuel & power) for England and Wales, changes to Part F (Ventilation) have been made, as well as the release of a new Part O for Overheating in dwellings.

The new Approved Documents for England can be found here:
Approved Document L, volume 1: dwellings
Approved Document L, volume 2: buildings other than dwellings
Approved Document F, volume 1: dwellings
Approved Document F, volume 2: buildings other than dwellings
• and an entirely new Approved Document O covering overheating

The ultimate aim is for new homes and buildings to be ‘net zero’, with a further uplift planned in 2025. Work to develop the next set of changes to Part L starts now and we welcome all CAB members to help us ensure that aluminium systems continue to be the best choice.

We will be working closely with members to help with the transition through our Technical Committee and Working Groups. Please contact us for further information at or by calling 01453 828851.