PAS 2038 is the standard governing energy efficiency retrofit for non-domestic and commercial buildings in the UK – everything from offices and schools to community halls and mixed-use blocks. With the built environment responsible for roughly 40% of UK greenhouse gas emissions and around 2 million non-domestic buildings needing upgrading to meet the UK’s 2050 net zero target, understanding what PAS 2038 actually requires matters well before a retrofit project starts, not once it’s already underway.
In this blog you’ll learn:
- What PAS 2038 is and how it differs from PAS 2035
- The stages of the non-domestic retrofit process
- What a PAS 2038 assessment actually involves
- Who leads a PAS 2038 project, and what qualifications matter
- When PAS 2038 applies, including funding-linked requirements
What is PAS 2038?
PAS 2038 is the retrofit standard for non-domestic buildings, published as the commercial counterpart to PAS 2035, the domestic retrofit standard. It covers all non-domestic and commercial buildings other than dwellings, but also applies to multi-residential building types such as student housing and hotels.
PAS 2038 follows a “whole building” approach to retrofit, aiming to:
- Reduce the environmental impact of buildings
- Improve energy efficiency
- Enable buildings to use low or zero-carbon energy sources
- Improve comfort, wellbeing, and occupant health and safety
- Improve the functionality, viability and durability of buildings
- Protect and enhance architectural and cultural heritage
How Does the PAS 2038 Retrofit Process Work?
PAS 2038 manages the retrofit process from initial brief through to completion and evaluation. The process mirrors PAS 2035 in structure, though – like the updated PAS 2035:2023 – it doesn’t use risk pathways. The stages are:
- Appointment of a project team and agreement of an initial brief
- Assessment of the building
- Identification of improvement options
- Agreement on intended outcomes
- Preparation of an improvement plan
- Delivery: retrofit works, testing, commissioning and handover
- Fine-tuning performance to meet or exceed targets
- Evaluation to confirm outcomes and identify any unintended consequences
For buildings over 1,000m², the improvement option evaluation stage carries an additional requirement: it must account for the “whole life” greenhouse gas emissions of any proposed retrofit measures – the emissions associated with manufacturing the materials and products, installing the measures, and the building’s ongoing operational energy use, combined. This assessment follows RICS’s Whole Life Carbon Assessment guidance, or conforms to BS EN 15804 and BS EN 15978.
What Does a PAS 2038 Assessment Involve?
The assessment stage is where PAS 2038 actually gets specific about the building in front of you, rather than the process in general. A PAS 2038 assessment covers four areas:
- Context and heritage: planning constraints, conservation area status, and any architectural or historic significance that limits what retrofit measures are viable
- Fabric and condition: the physical state of walls, roof, floors, windows and existing building services
- Occupancy: how the building is actually used – operating hours and occupant behaviour – so recommendations reflect real use rather than assumed use
- Energy performance: an energy baseline, established through Non-Domestic EPC modelling
In practice, this core assessment is often paired with diagnostic testing – air tightness testing and thermal imaging surveys are common additions – to give a more precise picture of where a building is actually losing energy, rather than relying on modelled assumptions alone.
The assessment feeds directly into the retrofit plan: an Improvement Option Evaluation showing which measures deliver the best return on carbon and cost, an updated Non-Domestic EPC reflecting the building’s baseline and potential and a fabric-first roadmap prioritising insulation and glazing ahead of low-carbon heating systems like air source heat pumps.
Who Leads a PAS 2038 Project?
Unlike PAS 2035, PAS 2038 doesn’t use a Retrofit Coordinator. Instead, a Retrofit Lead Professional oversees the project from inception to completion, with the specific skills required depending on the building’s complexity – reflecting the added complexity of commercial building services and occupancy patterns compared with domestic retrofit. A qualified Non-Domestic Energy Assessor, with knowledge of ISBEM and dynamic simulation modelling, typically plays a central role in the wider project team.
Our Expert Insights: Genuinely experienced PAS 2038 assessors are still relatively rare – it’s a newer standard than PAS 2035, and our technical team has delivered assessments across the full range of non-domestic building types it can apply to, from Grade-listed community halls to multi-storey Victorian schools, for real occupied premises rather than in theory.
How Does PAS 2038 Differ from PAS 2035?
Beyond who leads the project, there’s one further distinction worth knowing about: an alternative route reserved for smaller, simpler non-domestic buildings that are closer in character to a home than a commercial premises. A project can follow the PAS 2035 domestic route instead of full PAS 2038 only if the building meets all of the following:
- Floor area no greater than 500m², and no more than three storeys including any basement
- Load-bearing masonry construction (solid or cavity brick, block or stone), or timber-framed and clad externally in brick or timber
- Mostly pitched roofs with a timber structure, covered in tiles or slates
- Building services limited to heating, hot water, ventilation, lighting and small power – with no central air handling, mechanical cooling or air conditioning
Even where a building qualifies, the coordinator running the project under the PAS 2035 route must hold both the Non-Domestic Energy Assessor qualification and the Level 5 Diploma in Retrofit Coordination and Risk Management, use simplified modelling software such as iSBEM, and self-certify compliance under PAS 2035:2019. Miss any one of these conditions and the project defaults back to full PAS 2038.
When is PAS 2038 Required?
PAS 2038 isn’t yet a universal legal requirement for private projects, but it’s increasingly mandated for publicly funded schemes – including the Public Sector Decarbonisation Scheme and Public Sector Low Carbon Skills Fund – and for communal areas within mixed-tenure Warm Homes: Social Housing Fund programmes, where shared plant and building services need PAS 2038 assessment alongside the domestic PAS 2035 work. For privately funded commercial retrofit, PAS 2038 compliance is increasingly used as evidence for green lenders and ESG-linked finance providers that a retrofit will deliver genuine, verifiable carbon reduction.
A PAS 2038 condition survey and energy assessment across a 249m² Grade-unlisted community hall in Plymouth’s Barbican Conservation Area, supporting a sustainability funding application:
What’s next?
Whether you’re assessing a single commercial building or a mixed-tenure portfolio, PAS 2038 gives you the audit-proof evidence base funders, lenders and building control expect to see before work goes ahead.
We carry out PAS 2038 assessments across the full range of non-domestic building types, from heritage community buildings to large-scale commercial portfolios.
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