As of 1st April 2025, significant updates to PAS 2035:2023 have officially come into force. As an installer, it’s essential to understand how these changes impact your work, and that you know how to stay compliant.
What You Need to Know About PAS 2035:2023
Under the latest version of PAS 2035:2023, retrofit installers are required to ensure that Pre-Installation Building Inspections (PIBIs) are independently verified by a qualified individual before any installation begins.
To be compliant, every PIBI must:
- Have a unique identifier, and
- Include the full name of the person who completed the inspection.
These requirements strengthen quality assurance and improve traceability across all retrofit projects, ensuring a higher standard of installation and oversight.
Additionally, PAS 2035 continues to emphasise the “whole dwelling” approach, which treats properties as integrated systems. Instead of addressing individual measures (such as insulation or heating) in isolation, this approach considers how all components – walls, ventilation, air quality, and even occupant lifestyle – interact.
Key aspects of the whole dwelling approach include:
- Identifying and designing Energy Efficiency Measures (EEMs), either individually or in packages
- Ensuring compliance with standards during installation
- Ongoing monitoring and evaluation to reduce performance gaps and avoid unintended consequences
- Site inspections (remote or in-person), led by the Retrofit Coordinator, based on the size and complexity of the project
If you’re delivering PAS-compliant work, these requirements will increase the documentation and verification required, particularly around design, installation, and performance monitoring.
Who Needs to Take Action?
If you’re an installer delivering PAS compliant retrofit measures, these updates directly impact your day-to-day processes and responsibilities. The new requirements are crucial for maintaining:
- PAS 2035 certification
- Access to grant funding schemes
Whether you’re working independently or as part of a larger team, aligning your processes with these updated standards is essential.
How to Ensure Compliance
To stay compliant with PAS 2035:2023 requirements, follow these key steps:
- Review and familiarise yourself with the PAS 2035:2023 updates
- Arrange independent verification for PIBIs, where required
What Happens If You Don’t Comply?
The transition period has now ended. As of 1st April 2025, all retrofit work must comply with PAS 2035:2023. Any work carried out under the previous version is no longer considered compliant and will not qualify for funding or certification.
With the 18-month grace period officially closed, non-compliance could result in:
- Loss of access to government-backed funding
- Failure to meet standards
- Increased risk and liability for project issues due to a lack of oversight or traceability
The information provided in this blog is based on the official PAS 2035:2023 document, available from the British Standards Institution (BSI): Retrofitting dwellings for improved energy efficiency – Specification and guidance.
This blog highlights key updates but does not cover the full PAS 2035:2023 standard. Installers are responsible for reading and understanding the complete document to ensure compliance.
HIES is not liable for actions taken based solely on this content. Always refer to the official PAS document for full guidance.
Information sourced from: https://buildingenergyexperts.co.uk/resources/pas-2035-2023-changes/ & https://knowledge.bsigroup.com/