Is PAS 2035 mandatory?

For government-funded domestic retrofit (ECO4, GBIS, Warm Homes) yes — work must follow PAS 2035 with TrustMark registration.

Which qualification comes first?

Domestic Energy Assessor (Level 3), then Retrofit Assessor (Level 4), then Coordinator (Level 5).

PAS 2035 Training in the UK

PAS 2035 is the overarching specification for domestic retrofit projects. Any ECO4, GBIS or Warm Homes-funded measure must follow it, with a qualified assessor, coordinator and TrustMark registration. This guide explains the framework and training.

Last reviewed: August 2026

What PAS 2035 is

Published by BSI, PAS 2035 sets the process for whole-house domestic retrofit: assessment, coordination, design, installation, handover and monitoring. It exists to stop failed measures and protect households.

The qualified roles

Retrofit Assessor (Level 4) — surveys dwellings. Retrofit Coordinator (Level 5) — owns the project. Retrofit Designer — specifies measures. All must operate under a TrustMark-approved scheme.

Training route

Start with DEA (Level 3) → Retrofit Assessor (Level 4) → Retrofit Coordinator (Level 5). Funded routes exist via the Warm Homes Skills Programme and Skills Bootcamps.

FAQs

Is PAS 2035 mandatory?: For government-funded domestic retrofit (ECO4, GBIS, Warm Homes) yes — work must follow PAS 2035 with TrustMark registration.
Which qualification comes first?: Domestic Energy Assessor (Level 3), then Retrofit Assessor (Level 4), then Coordinator (Level 5).