Easy EPC
Lines Open (Monday - Friday)
9:00AM - 5:30PM

Updates to Welsh Building Regulations

In May 2022, the Welsh government released the next versions of their Building Regulations and Approved Documents: F1, L1 and O.

These changes will come into force from 23rd November 2022, however any buildings subject to a building notice, full plans application or initial notice submitted prior to 23rd November 2022 are not required to comply with the new regulations - provided that work for each building started before 23rd November 2023.

What do the Approved Documents Relate to?

Approved document F, Volume 1 - ventilation in dwellings.

Approved Document L, Volume 1 - Conservation of fuel and power in dwellings.

Approved document O - Overheating.

Amendments to the Building Regulations

The amendments to the Building Regulations include:

  • Using new performance metrics to provide new ways of measuring energy efficiency.
  • Changing the way on-site electricity generation systems are regulated.
  • Introducing regulations to reduce overheating.
  • Making a provision about ventilation standards when work to which Part L applies.
  • Making transitional provisions.
  • Making small changes with regard to self-certification schemes.

Amendments to the Approved Documents

The amendments to the Approved Documents include:

  • The guidance for new and existing dwellings in Approved Document F will be partially rewritten and replaced with Approved Document, Volume 1: Dwellings.
  • The guidance in Approved Document L1A (new dwellings) and L1B (existing dwellings) is being rewritten and replaced with Approved Document L, Volume 1: Dwellings.
  • New statutory guidance has been approved by Welsh Ministers, overheating risk is now addressed in its own Approved Document (O) after being removed from Part L and SAP.

Key Changes

The full changes can be found in the new Approved Documents, or the Building Regulations circular, however the key points are listed below:

  • SAP 10 methodology is being adopted.
  • The minimum energy efficiency standard for new builds will be an EPC rating of B (81).
  • Air tightness testing will become mandatory. Air tightness testers will have the choice of pulse or blower door methods.
  • Part O is created to address overheating risk as a standalone document, instead of being included in Part L.
  • The standards for fabric thermal elements will be tightened.
  • Compared with Part L 2014 standards, a 37% reduction in carbon emissions in new homes.
  • Alongside the existing carbon emissions stand, a Primary Energy Metric is to be introduced.

Commercial Building Regulation Changes

It's expected that the Welsh government will release the changes to commercial Building Regulations later in 2022.


Building Regulations - In this page, Building Regulations refer to The Building Regulations 2010 and any updated versions.

Approved Documents - Documents that set out ways for how to comply with each part of Building Regulations, in ordinary circumstances. These are not necessarily the only ways to comply and even may not be suitable in certain situations.

Thermal Elements - Walls, floors or roofs which separates a thermally conditioned part of a building from the external environment. This does not include windows or doors.

SAP - Standard Assessment Procedure.

SAP 10 - The most up-to-date version of the SAP methodology.

Methodology - A system of rules/procedures set out for doing something, and in the case of EPC's, a system of procedures for calculating energy efficiency and creating an EPC.

Certified by the following organisations
EPC Certification