PAS 2030 vs PAS 2035 at a glance
PAS 2030 is the standard for the people who fit the measures. PAS 2035 is the standard for the process around them: assessment, design, coordination and evaluation. The table below compares the two 2023 editions, which replaced the 2019 versions. PAS 2030:2023 states that its predecessor was withdrawn on 30 March 2025.
| PAS 2030:2023 | PAS 2035:2023 | |
|---|---|---|
| Full title | Installation of energy efficiency measures in existing dwellings – Specification | Retrofitting dwellings for improved energy efficiency – Specification and guidance |
| What it covers | Installing, commissioning and handing over each measure | Assessing the home, choosing and designing measures, coordinating and evaluating the project |
| Who works to it | The Retrofit Installer (the business fitting the measure) | The Retrofit Coordinator, Retrofit Assessor and Retrofit Designer |
| Unit of work | One measure at a time, each with its own annex | The whole dwelling as a single project |
| Who gets certified | The installing business, by a certification body | Retrofit Coordinators register with a TrustMark-approved scheme; funded projects are lodged on the TrustMark Data Warehouse |
| Typical evidence | Installation method statements, pre-installation inspections, handover packs | Retrofit assessment, improvement option evaluation, retrofit design, medium-term improvement plan |
| Applies to | Dwellings only (from the 2023 edition) | Dwellings only |
What is PAS 2030?
PAS 2030:2023 is the BSI specification for installing energy efficiency measures in existing homes. It covers the installation, commissioning and handover of each measure. The standard has a core set of requirements in Clauses 4 to 9, plus a separate annex for each measure, such as Annex B.8 for internal wall insulation. To comply, an installer must meet the core clauses and the annex for every measure they fit.
The PAS 2030 annexes are where the practical rules live. For internal wall insulation, Annex B.8 sets operative qualification rules, a minimum of 1 qualified operative per team of 4, and 12-monthly competence checks. It also requires a pre-installation building inspection that is independently checked, with a physical site visit for 1 in 10 of those checks. Our guide to what qualifications you need to install internal wall insulation covers these rules in detail.
PAS 2030:2023 states that it applies however an installation is funded. Its introduction notes that it was originally built around the Green Deal, but has always been suitable for any installation. In practice, installers pursue certification because funded schemes require it.
What is PAS 2035?
PAS 2035:2023 is the BSI specification for the whole retrofit process in a home: assessing the dwelling, evaluating improvement options, designing the measures, coordinating the work, and monitoring and evaluating the result. It treats the home as one project. That way, measures that interact, such as insulation and ventilation, are planned together rather than fitted one at a time.
The central role in PAS 2035 is the Retrofit Coordinator. PAS 2030:2023 (clause 3.22) defines this person as a qualified specialist retrofit project manager. The Retrofit Coordinator takes overall responsibility for assessing the home, identifying and specifying the measures, and monitoring and evaluating the result. Two other qualified roles feed into the Retrofit Coordinator's work:
- the Retrofit Assessor (clause 3.21), who surveys the home
- the Retrofit Designer (clause 3.24), who produces the retrofit design to PAS 2035:2023
PAS 2035 exists because single measures fitted in isolation can cause damp, condensation and ventilation problems. The Measures Interaction Matrix, printed in both standards as Figure A.1, shows which measures affect each other. PAS 2035:2023 requires those interactions to be taken into account in the design.
Does an installer need PAS 2030, PAS 2035 or both?
An installer needs PAS 2030 certification to fit measures on funded schemes, and must work to a retrofit design produced under PAS 2035. The installing business does not normally become a Retrofit Coordinator itself. It needs a PAS 2035 design and coordinator in place on every funded job. The rules are designed to work together: PAS 2030:2023 states that PAS 2035:2023 is meant to be read and used alongside it.
The government's Warm Homes: Local Grant guidance (updated June 2026) gives a current example. All upgrades must follow PAS 2035:2023. Installers must be TrustMark registered and certified under the latest PAS 2030, or by MCS for low-carbon heating. Every measure must be lodged on the TrustMark Data Warehouse.
PAS 2030:2023 also says the installer should not start work if the design is missing critical information. The standard lists what installers expect a design to cover. For internal wall insulation, that includes:
- moisture risk analysis
- ventilation requirements
- thermal bridging details
- the specific system chosen
If those are missing, the installer refers the issue back to the Retrofit Coordinator before starting.
Which standard covers which part of a retrofit job?
PAS 2035 covers everything before and after the physical work, and PAS 2030 covers the physical work itself. A typical funded retrofit runs through eight stages, and each one sits mainly under one of the two standards.
| Stage | Who does it | Governed by |
|---|---|---|
| 1. Retrofit assessment of the home | Retrofit Assessor | PAS 2035 |
| 2. Improvement option evaluation and medium-term plan | Retrofit Coordinator | PAS 2035 |
| 3. Retrofit design | Retrofit Designer | PAS 2035 |
| 4. Pre-installation building inspection | Retrofit Installer (independently checked) | PAS 2030 |
| 5. Installation of each measure | Retrofit Installer's operatives | PAS 2030 (core and measure annex) |
| 6. Commissioning and handover pack | Retrofit Installer | PAS 2030 |
| 7. Project lodgement and sign-off | Retrofit Coordinator | PAS 2035 (TrustMark when funded) |
| 8. Monitoring and evaluation | Retrofit Coordinator | PAS 2035 |
Is PAS 2030 or PAS 2035 a legal requirement?
Neither PAS 2030 nor PAS 2035 is law. Both are voluntary BSI specifications, and PAS 2030:2023 itself states that complying with a PAS does not grant immunity from legal obligations. They become mandatory in practice when a funding scheme or contract requires them. That includes ECO4, the Warm Homes: Local Grant and most social housing programmes.
The law that does apply to all retrofit work is the Building Regulations, covering fire, moisture, ventilation and energy efficiency, and PAS 2030:2023 draws attention to it for each measure. A private, self-funded installation does not need PAS certification, but the Building Regulations still apply in full.
Frequently asked questions
Do I need to be a Retrofit Coordinator to install insulation?
No. Installers fit measures under PAS 2030 and do not need to be Retrofit Coordinators. On funded jobs, a separate qualified Retrofit Coordinator oversees the project under PAS 2035. The installer works to the coordinator's design and refers any problems back to them.
What qualification does a Retrofit Coordinator need?
A Retrofit Coordinator typically holds a Level 5 Diploma in Retrofit Coordination, offered by awarding bodies such as ABBE, and registers with a TrustMark-approved coordinator scheme. Check the current requirements with TrustMark before enrolling, as they apply to the 2023 edition of PAS 2035.
When did PAS 2030:2023 and PAS 2035:2023 come into force?
PAS 2030:2023 and PAS 2035:2023 were published in 2023 with a transition period. PAS 2030:2023 states that installers were expected to fully comply with both 2023 editions by 30 March 2025, when the 2019 version of PAS 2030 was withdrawn.
Does PAS 2030 apply to commercial buildings?
No. From the 2023 edition, PAS 2030 applies only to dwellings, in line with PAS 2035, which applies only to dwellings. Non-domestic retrofit follows other standards and contract specifications.
Is MCS the same as PAS 2030?
No. MCS certifies installers of low-carbon heating and renewable technologies such as heat pumps and solar panels. PAS 2030 certifies installers of energy efficiency measures. The Warm Homes: Local Grant accepts PAS 2030 or MCS certification depending on the measure being installed.
For the routes into the industry, see how to become a retrofit installer in the UK.
See also what a retrofit coordinator does, and how to become one.
How Nexis Academy can help
Nexis Academy is a City & Guilds Approved Centre (T91185) in Manchester, delivering practical internal wall insulation training aligned to PAS 2035 and PAS 2030. See our internal wall insulation course, or read what the end of ECO4 means for installers.
Sources
- BSI, PAS 2030:2023 Installation of energy efficiency measures in existing dwellings — Specification: Introduction and Foreword; clauses 3.22–3.25; Annex A (Figure A.1); Annex B.8.
- Department for Energy Security and Net Zero, Warm Homes: Local Grant policy guidance, updated June 2026: "Measures: Standards".