New Part L for Wales (Extensions and Non-Resi)

There's a new Approved Document Part L coming into force in Wales from March 4th 2027. These changes don't just apply to new build dwellings…

Photo evidence requirements are being extended to cover non-residential buildings in Wales from 2027.

🏘️ Extensions:

A new tier of requirements has been added to the Consequential Improvements rule for residential extensions in Wales, bringing a touch of Future Homes Standard to the renovation market.

This applies to any extension which is >40sqm, and at least the same number of storeys as the original house.

The designer will need to pick one of the following options:

☀️ Install at least 2kWp of PV to the dwelling (either on the extension or existing building), or

💧 Install a solar thermal system to reduce hot water demand, or

♨️ Replace the existing heating system with a heat pump, or

🃏 Play the Wildcard (Not its official name): Complete any other improvements to the existing building to offset enough energy as the equivalent of 2kWp PV.

❌ The dwelling is exempt if it already has PV or a heat pump, or is protected / unsuitable for some other reason.

⚖️ Extension Targets:

As before, for a heavily glazed extension, SAP can be used to prove the overall specification complies, using targets based on the actual dwelling with a notional extension.

But there are new targets in this latest revision of Part L, so extensions must be assessed against the Emission Rate, Primary Energy Rate, and the new Energy Use Intensity targets.

🏭 Non-Domestic:

Unlike in 2022, where Part L’s launch was staggered in a confusing manner, L2 also changes on 4th March, and follows many of the same principles as covered in the residential sector. The new SBEM methodology hasn’t been released yet, but expect heat pumps and PV will be required wherever feasible.

📷 Part L2 (2026) in Wales introduces Photographic Evidence for non-domestic buildings.

This has applied to new dwellings in both England and Wales since 2022, but Wales is now going alone by adding this requirement to the commercial sector.

The types of photos required are the same as for dwellings, starting with foundation insulation, working right up to installed HVAC and PV systems.

Anyone can take the photos, which must be digital and geotagged. The SBEM assessor needs to review the photos before EPCs can be signed and lodged.

The images also need to be provided to building control and the owners.