What is included in a PAS 2035 retrofit assessment?

The standard is deliberately broad in scope. PAS 2035 introduces a whole-house, whole-lifecycle approach to retrofit and defines the roles, responsibilities and processes that must be followed at every stage, from assessment, coordination and design through to installation and evaluation². PAS 2030:2023 is designed to complement it, focusing on the delivery phase of retrofits³. So the assessment is one half of a pair: PAS 2035 governs how the project is planned and managed, PAS 2030 governs how the work is installed.

For a household, the assessment is the point at which a plan stops being generic. It is also the point at which a project acquires a named person responsible for it, because PAS 2035 requires a retrofit coordinator role⁴. What follows sets out what the assessment covers, who the standard binds, the conditions and exceptions, and how the process runs in practice.

What the assessment covers, and what it is not

The assessment stage exists because retrofit decisions made without dwelling-level evidence tend to go wrong. PAS 2035 provides a robust framework for managing risk, balancing competing priorities and delivering better retrofit outcomes⁸, and the assessment is where that balancing starts. The assessor records the dwelling and its occupancy so that the designer can judge which measures suit this building rather than a typical one of its age and type.

It is not an EPC, and it is not a quote. An EPC rates performance and offers recommendations; the retrofit assessment feeds a design. It is also not the design itself. Under PAS 2035:2023 the Retrofit Assessment requirements are the same as the existing Path B requirements⁹, while the Retrofit Design requirements are the same as the existing Path A requirements but with additional clauses depending on the characteristics of the project⁹. Assessment and design are separate stages with separate requirements, and the assessment comes first.

The scope of the standard is the whole life cycle of a retrofit project, from the initial engagement with a client, through the assessment, design, installation and subsequent evaluation and monitoring stages¹⁰. That matters to a household because it means the assessment is not a one-off document. It is the first link in a chain that ends with evaluation, and the later stages depend on what the assessor recorded.

Who the standard applies to

PAS 2035 applies to domestic retrofit projects, and its reach is widest where public money is involved. It provides a specification that any publicly funded retrofit should comply with⁷, and the Welsh Government describes it as the overarching UK retrofit standards framework¹. PAS 2035:2023 covers the whole life cycle of a retrofit project¹⁰, and PAS 2035:2019 covers the same ground, from the initial engagement with a client through assessment, design, installation and evaluation¹¹.

The roles are defined rather than implied. PAS 2035/30:2019 sets out five: retrofit coordinator, assessor, designer, installer and evaluator⁶. Retrofit Coordinators are required for all domestic retrofit projects in order to comply with PAS 2035⁵, and the standard has to be managed by a qualified Retrofit Coordinator¹². The coordinator is certified by Trustmark¹³. PAS 2035 acts as the overarching document which helps to co-ordinate the activities of those in roles which are, for the most part, new¹⁴.

For non-domestic buildings the picture differs. PAS 2038:2021 ensures retrofit solutions are tailored to property types like offices, hospitals and multi-residential buildings³. A household in a flat or a house is therefore in PAS 2035 territory, while a landlord retrofitting a mixed-use block may be working to a different standard.

Conditions, exceptions and the version question

The most common practical question is which version of the standard a project falls under, and the answer has been moving. PAS 2035 was introduced in 2019 as a clear framework for best practice in the energy retrofit of domestic properties¹², and PAS 2035:2023 was first introduced in 2019 as a structured framework for managing domestic retrofit projects³. The 2023 revision is the current reference point for funded work: all Retrofit Assessments in Wave 3 of the Warm Homes Social Housing Fund must be done or upgraded to PAS 2035:2023¹⁶.

Older projects were given a deadline. For PAS 2035:2019 projects, the retrofit assessment and all measures must be handed over before 30 March 2025¹⁷. That date has passed, so assessments now sit under the 2023 version.

Two exceptions are worth knowing. First, the 2023 revisions included clauses to facilitate scale retrofit by allowing Retrofit Design to commence based on assessments of archetypes¹⁸. That is a volume mechanism for programmes, not a route for a single household wanting its own home assessed. Second, PAS 2035:2019 retrofits used Medium Term Improvement Plans for certain levels of retrofit, such as those receiving three or more energy efficiency measures¹⁹. The standard also requires the production of longer-term retrofit plans²⁰, which is why an assessment can lead to a staged programme rather than a single visit from a installer.

How the assessment is carried out, stage by stage

The process is sequential, and each stage has a defined owner. PAS 2035 pertains to retrofit standards and is designed to clarify the responsibilities of those in retrofit roles and the qualifications they must hold prior to the commencement of any physical retrofitting installation¹⁴. Nothing is installed until the assessment and design are complete.

1. Assessment. A Retrofit Assessor surveys the dwelling and records its construction, condition, occupancy and performance. PAS 2035 calls for a Level 3 qualification in Retrofit Assessment².
2. Coordination. A qualified Retrofit Coordinator takes responsibility for the project¹², a role required by PAS 2035⁴.
3. Design. The coordinator commissions a Retrofit Design, which under PAS 2035:2023 carries the Path A requirements plus additional clauses depending on the project⁹.
4. Installation. The work is delivered to PAS 2030:2023, which focuses on the delivery phase³.
5. Evaluation and monitoring. The project closes with evaluation, part of the whole life cycle the standard covers¹⁰.

The assessment stage is also where ventilation and heritage questions surface early. Ventilation work in retrofit is carried out using the guidance of PAS 2035²¹, and PAS 2035 provides a robust framework for managing risk, balancing competing priorities and delivering better retrofit outcomes⁸, which is precisely the function it serves on older and harder-to-treat buildings.

What it means for a household's energy independence

A retrofit assessment does not generate energy and does not disconnect anything. What it does is establish, on paper, what a specific dwelling needs and in what order, which is the precondition for a plan that a household can act on over years rather than weeks. PAS 2035 creates a framework for deep retrofit projects that are high quality, safe and fit for the future²², and it requires the production of longer-term retrofit plans²⁰. That is the independence dividend: a documented route rather than a series of disconnected purchases.

The dependence that remains is real. The assessment is carried out under an industry-led quality standard that provides best practice for retrofit, taking a whole house approach²³, and it is delivered by certified businesses rather than by the household. The coordinator is certified by Trustmark¹³, and the standard has to be managed by a qualified Retrofit Coordinator¹², so a household is buying into a professional chain it does not control. Where public funding is involved, the specification is set by the scheme: PAS 2035 provides a specification that any publicly funded retrofit should comply with⁷, and scheme rules decide what is funded.

The assessment also does not cover everything a household might want. It is a domestic standard, with PAS 2038:2021 handling non-domestic property types³. And it is a standard, not a guarantee: PAS 2035 provides a robust framework for managing risk⁸, but the quality of any individual project still rests on the people certified to carry it out. For a householder, the practical value is a written, versioned plan that names who is responsible at each stage, and a clear record of what was assessed and why.