The Welsh Government's consultation on Building Regulations Part L closed on 17 November 2025, ending a period that ran from 26 August 20251. The review covers the conservation of fuel and power, and the government said it wanted views on "plans to improve energy efficiency standards in new and existing homes and buildings"1.
The consultation was not confined to Part L. It also covered proposed changes to Part F (Ventilation) and Part O (Overheating) of the Building Regulations, together with the associated Approved Document guidance1. Consultation versions of the documents were published alongside the main consultation document and a consultation stage impact assessment1.
The published papers were:
| Document | File size |
|---|---|
| Consultation document | 1 MB |
| Approved Document F: consultation version | 2 MB |
| Approved Document L volume 1: consultation version | 2 MB |
| Approved Document L volume 2: consultation version | 2 MB |
| Approved Document O: consultation version | 613 KB |
| Building Regulations review: consultation stage impact assessment | 544 KB |
The Welsh Government described the exercise in its own terms:
"We are consulting on the impacts of changes to Building Regulations Part L (conservation of fuel and power)."
Part L sits alongside the other parts of the Building Regulations in Wales, which differ from the regime in England. For householders, the practical content of Part L is the standard that walls, roofs, windows and doors must meet, which is set out in our guide to Building Regulations Part L: insulation and glazing requirements. Ventilation is governed separately under Building Regulations Part F, and the Welsh position on fabric standards is covered in Welsh Building Regulations for insulation and glazing.
Why it matters for households
Part L sets the energy performance a home must achieve when it is built or when certain work is carried out on it. Changes to it therefore affect what a new home in Wales is built to, and what is required when existing homes are extended, altered or have windows and doors replaced. Because the review also covered ventilation and overheating, the proposals touched on how a home is kept fresh and how it is kept from getting too hot, both of which bear on how much energy a household uses and how comfortable the home is through the year. A tighter fabric reduces the energy needed to keep a home warm, which is the basis of a household's independence from rising fuel costs. The consultation stage impact assessment published with the papers sets out the government's own view of the costs and benefits, but the outcome of the review has not been reported.
What happens next
The consultation page was last updated on 27 February 2026 and now carries a summary of responses, published as a PDF of 1 MB1. No date for a government decision or for revised Approved Documents has been reported. The wider process by which such consultations lead to changed rules is set out in Energy Consultations: How Rules Are Proposed, Decided and Changed.