PAS 2035:2023 Changes

With the publication of PAS 2035:2023, several significant updates have been introduced to improve scalability, streamline processes, and strengthen compliance. This blog explores the key changes from PAS 2035:2019 and the difference in approaches required for this wave.

In this blog, you’ll learn:

• The key changes introduced in PAS 2035:2023
• How the updated standard supports large-scale retrofit projects
• The new requirements for airtightness, ventilation, and moisture management
• The evolving role of the Retrofit Coordinator and Main Contractor
• How PAS 2035:2023 aligns with other industry standards and policies

Adoption Timeline for PAS 2035:2023

It is intended that users will commence adoption of PAS 2035:2023 immediately following publication, with the goal of fully meeting its requirements and claiming compliance with PAS 2030:2023 (and therefore PAS 2035:2023) from the 30th of March 2025. At this point, PAS 2035:2019+A1:2022 will be withdrawn, so retrofit professionals must transition to the new standard now.

Key Changes in PAS 2035:2023

Here are some of the key differences highlighted in the document:

1. Updated Guidance Clauses

PAS 2035:2023 aligns with national policy and places greater emphasis on consumer protection. Guidance clauses have been refined to provide clearer direction for retrofit professionals, ensuring that projects meet both regulatory and quality assurance standards.

2. Supporting Large-Scale Retrofit

To facilitate large-scale retrofitting, the standard allows design work to begin based on assessments of property archetypes. However, every individual dwelling must still undergo its own retrofit assessment, improvement options evaluation, and medium-term improvement plan before project completion.

3. Inclusion of BEIS Retrofit Technical Guides

PAS 2035:2023 integrates the BEIS retrofit technical guides, making them a formal reference within the standard. This helps unify best practices and technical methodologies across the industry.

4. Simplified Risk Assessment Process

Risk assessment has been streamlined to remove unnecessary complexities. Instead of a separate normative annex (Annex B in PAS 2035:2019), risk considerations are now integrated into the responsibilities of the Retrofit Coordinator throughout the project lifecycle.

5. Shift to Whole-Dwelling Retrofit

The updated standard reinforces a whole-dwelling approach, moving away from a measures-based retrofit strategy. It introduces a stronger focus on the role of the Main Contractor (where applicable) and clarifies that compliance with PAS 2035 ultimately falls on the PAS Certification holder – whether that is the Main Contractor or the Retrofit Installer.

6. Clarification of the Retrofit Coordinator’s Role

The Retrofit Coordinator’s responsibilities have been expanded, particularly regarding site visits and documenting non-compliance. Their oversight role now spans from project inception to completion, ensuring adherence to PAS 2035.

7. Mandatory Medium-Term Improvement Plans

Unlike PAS 2035:2019, where medium-term improvement plans were optional, PAS 2035:2023 makes them a mandatory requirement. These plans outline a structured roadmap for future energy efficiency improvements beyond the immediate retrofit project.

8. Airtightness Strategy Requirement

Projects must now incorporate an airtightness strategy, including specific targets and testing requirements where applicable. This ensures a more structured approach to reducing uncontrolled air leakage and improving energy efficiency.

9. Considerations for Historic Buildings

A new Annex E has been introduced to guide assessments of historic and traditional buildings. This aligns with BS 7913 and ensures that retrofit measures respect the architectural and material integrity of older properties.

10. Simplified Ventilation Requirements (Annex C)

Ventilation requirements have been revised and simplified in PAS 2035:2023 to align with Approved Document F. Functional ventilation testing is now a core requirement, ensuring that systems perform effectively post-retrofit.

11. Strengthened Monitoring and Evaluation

The new standard references BS 40101 for Building Performance Evaluation, emphasising a continuous approach to monitoring and evaluating energy performance from project initiation through to post-completion.

12. Distressed Replacement of Heating Appliances

A new process allows distressed replacement of heating appliances to be retrospectively brought into compliance with PAS 2035, ensuring flexibility while maintaining regulatory standards.

13. Enhanced Climate Resilience and Adaptation

With growing concerns about climate change, PAS 2035:2023 strengthens requirements for assessing overheating risk and ensuring that retrofit measures contribute to long-term climate resilience.

14. Stricter Pre-Installation Building Inspections (PIBI)

The qualifications and requirements for independent inspections of pre-installation building inspections (PIBI) have been reinforced. These inspections must meet the revised PAS 2030 annex requirements.

15. Improved Moisture Management Guidance

Moisture risk management has been updated to align with BS 5250, ensuring that retrofit projects do not inadvertently introduce damp or condensation risks.

What’s Next?

The updates in PAS 2035:2023 reflect the evolving needs of the retrofit industry, strengthening consumer protection, improved scalability and promoting a whole-dwelling approach. As the industry shifts toward these more comprehensive standards, staying compliant with PAS 2035:2023 is essential.

To successfully navigate these changes and ensure your projects are fully compliant, timely adoption of the updated standard is critical. If you need support with PAS 2035 compliance and retrofit assessments, get in touch with us today. Our experts can help you meet the latest standards and ensure your retrofit projects are a success.