Retrofit assessment (whole-house retrofit appraisal)
Retrofit assessment
The whole-house assessment behind a coordinated retrofit: fabric, moisture risk, ventilation and a staged improvement plan under PAS 2035 principles.
Last reviewed 31 August 2026
What is a retrofit assessment?
A retrofit assessment is the whole-house appraisal that sits at the start of a coordinated energy retrofit. It records the building's construction, condition, moisture risk, ventilation and occupancy, so that improvement measures are planned as a system rather than installed one at a time. It follows the whole-house approach set out in PAS 2035, the UK framework for retrofitting domestic buildings for energy efficiency.
At a glance
- Framework
- PAS 2035, the retrofit standard for domestic energy efficiency work.
- Core principle
- Whole house, not single measures fitted in isolation.
- Central risk
- Unmanaged moisture and ventilation following fabric improvement.
- Output
- A staged medium-term improvement plan, not a single quotation.
Why single measures cause problems
Improving one element changes how the whole building behaves. Sealing a draughty house without adding ventilation raises internal humidity. Insulating a wall internally moves the dew point and can leave the masonry colder and wetter than before.
The whole-house approach exists because the failures in domestic retrofit have overwhelmingly been interaction failures rather than product failures. The measure worked; the building's moisture balance did not survive it.
What the assessment records
The assessment is deliberately broader than an energy calculation. It looks at construction and condition, existing defects, moisture and ventilation, occupancy patterns, heritage and constraint issues, and any exposure factors that affect what is safe to install.
Condition matters as much as energy performance. There is no value in insulating a roof space beneath a failing covering, and no sense in sealing a building that is already suffering penetrating damp.
- Construction type, age and any previous alterations
- Existing defects, damp and repair needs that must precede retrofit
- Current ventilation provision and how the property is occupied
- Heritage status, exposure and site constraints
- Moisture risk arising from each candidate measure
The improvement plan
The output is a medium-term plan rather than a single job. It sequences measures so that each stage stands on its own, so ventilation keeps pace with airtightness, and so nothing installed early gets torn out later to accommodate something else.
That sequencing matters most where the work is being funded in tranches, which is the normal domestic situation. A plan that assumes the whole scheme happens at once is not much use to an owner spending over five years.
Jurisdiction and funding
PAS 2035 is a UK-wide publicly available specification, but the funding schemes that require it and the support available to households are administered separately in England, Scotland, Wales and Northern Ireland.
Where a grant is involved, the scheme rules usually set out who must carry out the assessment and to what standard. Confirm the requirement for your nation and your scheme before instructing anyone, including us.
Who this is for
A good fit if
- Owners planning a staged, multi-measure energy retrofit
- Owners of traditional or solid-wall buildings where moisture risk is real
- Landlords planning fabric upgrades across a property or small portfolio
- Anyone whose funding scheme requires a whole-house assessment
Not the right choice if
- Anyone wanting a single measure fitted quickly with no wider appraisal
- Producing an EPC or a scheme compliance certificate
- Structural design or heating system sizing calculations
Before the first measure is installed
Retrofit that starts with a product rather than an assessment is where the damage happens.
1.Deal with existing defects and damp first
Insulating over an unresolved moisture problem makes it worse and hides it.
Damp surveys2.Assess the whole house, not the measure being sold
The interaction between fabric, moisture and ventilation is the thing that fails.
3.Plan ventilation alongside airtightness
Every improvement in airtightness has to be matched by a deliberate ventilation strategy.
4.Stage the plan to your actual budget
A five-year sequence where each step is useful alone beats a scheme you cannot finish.
Energy efficiency surveys
When to bring in a specialist
- Retrofit design, coordination and installation under a funded scheme: the appointed scheme professionals required by that scheme.
- Heating system design: a qualified heating engineer.
- Listed building and conservation area consent: your local authority conservation officer.
- Structural calculations, load paths and remedial design: a structural engineer. A surveyor describes and diagnoses; it does not design.
Common questions
Limitations and sources
- This assessment is advisory. It does not by itself satisfy the specific role requirements of any particular funded retrofit scheme; confirm what your scheme requires.
- Predicted performance improvement depends on occupancy, fuel prices and installation quality, so no specific saving is guaranteed.
- Retrofit funding and scheme rules differ across England, Scotland, Wales and Northern Ireland.
- Nothing on this page is a professional opinion about a specific property. KJ Surveyors has not inspected your building, and general guidance cannot replace an inspection and report.
Source: UK Government · checked August 2026
Source: Scottish Government · checked August 2026
Source: Historic England · checked August 2026
Source: UK Government · checked August 2026
Last reviewed 31 August 2026.
Where to go next
- energy efficiency surveys — the fabric-focused advice that sits inside a wider plan.
- thermal imaging — to establish the current performance baseline.
- surveying advice — for background before committing to a programme.
Planning a whole-house retrofit?
Tell KJ the property construction, its condition and what you hope to achieve. KJ will explain what a whole-house assessment should cover first.
KJonline
Free surveying guidance across North West England
Hi, I'm KJ. Tell me about the property or the surveying advice you need and I'll help you work out the right next step.
KJ gives general guidance only and has not inspected your property. A professional opinion follows an inspection by a surveyor.