Retrofit assessment (PAS 2035)
A retrofit assessment is the survey of a property's fabric, services, ventilation and occupancy carried out under PAS 2035, the British Standards Institution's specification for domestic retrofit, to produce a costed plan of energy improvements in the order they should be done. It is carried out by a TrustMark-registered retrofit assessor and reviewed by a retrofit coordinator, and it is the first stage of any grant-funded or coordinated retrofit. For a landlord it is the document that turns "get to EPC C" into a list of measures with a price and a modelled rating after each.
What it includes
A condition survey of the building; an occupancy assessment covering how the home is used and ventilated; a significance assessment for older or traditional buildings; a whole-dwelling energy model; and a medium-term improvement plan setting out measures in sequence, fabric first, with the expected energy performance certificate outcome. The current edition is PAS 2035:2023, which applies to all work funded through TrustMark-lodged schemes.
Who does it
A retrofit assessor is a different role from the domestic energy assessor who produces an EPC, although some people hold both. Under PAS 2035 the assessor surveys, the coordinator takes responsibility for the plan and its delivery, and the installer works to it; grant schemes such as the Warm Homes Local Grant and ECO4 require all three roles and lodge the work with TrustMark, which can order non-compliant work remediated within eight weeks. TrustMark's register lists assessors and coordinators by postcode.
Cost
Typically £250 to £500 for a single dwelling as at September 2026, more for a large or traditional building. Under the minimum energy efficiency standards regime requiring privately rented homes to reach EPC C by 1 October 2030, the reasonable cost of the assessment counts towards the £10,000 per-property cap that unlocks a cost-cap exemption, so it is never wasted money.
Why it comes first
The MEES standard expects landlords to invest in fabric before heating counts, and the Boiler Upgrade Scheme grant for a heat pump is best claimed once the fabric is done. An assessment that starts with a heat pump is wrong; one that starts with loft and cavity insulation and models the rating after each step is what the standard, the grant schemes and the exemption evidence all require. Ask any assessor whether the model uses the reformed EPC metrics rather than the old ones.
From working with landlords across the UK, the ones best placed for 2030 had the assessment done in 2025 and 2026 while assessors and grants were available; those who bought a single measure first often found it did not move the rating. Run the property through the EPC improvement calculator before booking, and see who does the work at each stage in the best EPC improvement providers for landlords. August's compliance tracker holds the assessment, the invoices and the post-works EPC as the evidence file.
Last reviewed: September 2026.
