The British Standards Institution (BSI) published the updated PAS 2035/2030:2023 retrofit standards in September 2023, according to a guide to the standards published by the Installation Assurance Authority1. The earlier PAS 2035/2030:2019 standards were officially withdrawn and replaced at midnight on 30th March 20251.
The standards set out best practice for "whole house" retrofits of domestic dwellings from project inception to handover and evaluation1. PAS 2030:2023 is the specification for installers to follow when installing products and systems designed to improve the energy efficiency of existing homes, and is required when participating in government-funded energy efficiency projects in the UK, such as the Energy Company Obligation (ECO) and Warm Homes Social Housing Fund1. Compliance with PAS 2035/2030:2023, as well as TrustMark registration, is a requirement of domestic retrofit under government energy efficiency schemes1.
The 2023 edition removes the risk pathways for assessment, design and advice. The retrofit assessment requirements are the same as the existing Path B requirements, while the retrofit design requirements are the same as the existing Path A requirements but with additional clauses depending on the characteristics of the project1. An Improvement Options Evaluation (IOE) and Medium Term Improvement Plan (MTIP) are required for all projects, and retrofit advice is to be provided at project inception, retrofit design completion, completion of the IOE and at handover1. Qualification criteria have been updated and are measure specific1.
Other changes include:
| Area | Change under the 2023 standards |
|---|---|
| Monitoring and evaluation | Intermediate and advanced monitoring replaced with Further Monitoring & Evaluation, requiring a plan designed in accordance with BS40101 Building Performance Evaluation; the Retrofit Evaluator must not be the Retrofit Coordinator and must be independent of all other retrofit roles1 |
| Retrofit Coordinator site visits | Evidence may be collected through an in-person or virtual/remote site inspection or, where not possible, by a third party1 |
| Historic significance | Annex E now includes a simplified BS7913 assessment with key values of significance1 |
| Airtightness | Where fabric measures are included, an airtightness and air leakage testing strategy must be developed as part of the retrofit design, with an approved test for every dwelling where a target is set1 |
| Ventilation | Requirements updated in line with the Building Regulations, with additional clauses in Annex C where they exceed standards currently in effect1 |
| Pre-installation building inspection | Required for all fabric and insulation measures, independently checked by an appropriately qualified person before installation begins1 |
The Installation Assurance Authority Commercial Services offers an Independent Surveillance of Assessment service, priced at £30 per lodgement for every fabric measure, covering 100% desktop surveillance and 1 in 10 physical site inspections, with an annual scheme fee of £300 plus VAT1.
Why it matters for households
The standards govern how retrofit work is assessed, designed, installed and evaluated, and compliance with them, alongside TrustMark registration, is a condition of domestic retrofit under government energy efficiency schemes1. For a household, that shapes what a project involves in practice: an assessment of the dwelling, a design stage, an improvement options evaluation and a medium term improvement plan, advice at set points, and evidence collected during installation1. The requirement for a pre-installation building inspection for all fabric and insulation measures, independently checked before work starts, is intended to confirm suitability and compliance for each property1. The airtightness and ventilation clauses address how a home performs after fabric measures are fitted, including testing where an airtightness target is set and assessment of existing ventilation where measures fall into Category B or C under Approved Document F, or where there is evidence of condensation or mould1. The independence rule for Further Monitoring & Evaluation separates the evaluator from the coordinator and other retrofit roles1. The PAS 2035 and PAS 2030 retrofit standards sit alongside the wider framework of standards bodies and insulation product standards, certification and guarantees.
What happens next
The PAS 2035/2030:2019 standards were withdrawn at midnight on 30th March 2025 and replaced by the 2023 editions1. No further dated steps are given in the source.
Sources1 cited
- A guide to PAS 2035/2030:2023 standards, theiaa.co.uk