Elmhurst responds to consultation on updates to Welsh Building Regulations

On 26th August 2025, the Welsh Government released its consultation on proposed updates to Building Regulations Parts L, F, and O, aimed at improving energy efficiency and supporting Wales’ net-zero ambitions. This consultation closed on 17th November 2025 and Elmhurst Energy submitted a detailed response on behalf of its members, welcoming the opportunity to contribute to the development of robust, fair, and future-ready standards.

What did the consultation propose?

The consultation proposes significant changes to the regulatory framework for both new and existing buildings, including the introduction of more ambitious energy performance targets, enhanced ventilation and overheating guidance, and a stronger emphasis on low-carbon heating and renewable technologies.

Key proposals include:

• Uplifted Energy Efficiency Standards: For new dwellings, the Welsh Government’s preferred Option 1 aligns with England’s Future Homes Standard, reducing cross-border complexity while improving performance over Part L 2022.
• Fabric-First and Renewable Energy Requirements: The consultation explores introducing a functional requirement for renewable electricity generation, alongside a more ambitious notional dwelling specification. Elmhurst supports this dual approach, provided exemptions are clearly defined.
• Transition to the Home Energy Model (HEM): While Elmhurst supports HEM as the future compliance tool, they recommend continued use of SAP until HEM is fully operational, with clear timelines and training for assessors.

Elmhurst’s Consultation Response

A summary of the key responses that Elmhurst has submitted to the consultation are as follows:

Cross-Border Alignment – uplift in energy efficiency standards (targets for performance metrics)

Elmhurst endorsed Option 1 for new dwellings, which mirrors England’s Future Homes Standard. This approach reduces regulatory divergence for developers operating across the UK while delivering a meaningful uplift in energy performance over the 2022 baseline.

Ventilation and MVHR Scrutiny

The response raised concerns about the real-world performance of MVHR systems, calling for independent testing by competent persons and better commissioning standards. Elmhurst also supported improved guidance in Approved Document F to ensure ventilation systems are installed and maintained correctly.

Metric Reform and Fabric-First Focus

Elmhurst rejected the use of Energy Use Intensity (EUI) in compliance metrics, warning of confusion and unintended behaviours. Instead, they proposed a Welsh Fabric Energy Efficiency Standard (FEES) to ensure robust building fabric performance and support heat pump efficiency

Extension of Part O to Existing Dwellings

Elmhurst’s response is supportive of extending Part O to cover existing homes. The responses reflects a consistent emphasis on occupant comfort, risk-based regulation, and clear, enforceable guidance to ensure overheating risks are addressed proactively in both new and existing residential settings.