How is an EPC assessment carried out?
An accredited assessor visits and records the dimensions, construction, insulation, heating, hot water, glazing and lighting of the property. Nothing is drilled or lifted. A typical home takes 30 to 60 minutes, and NextDay EPC lodges the finished certificate to the national register within 24 hours.
- The survey is entirely non-invasive.
- Unverified elements are defaulted, and the defaults are conservative.
- Loft access materially changes the recorded insulation value.
- Extensions are recorded as separate construction elements.
An EPC assessment is a non-invasive survey. Nothing is drilled, lifted or dismantled. The assessor records what the building is made of and what heats it, then runs those inputs through government-approved software. For a typical Coventry home the visit takes 30 to 60 minutes.
What the assessor records
- Dimensions — every room measured, and the property drawn up floor by floor
- Construction — the type and age of each external wall, and whether there is a cavity
- Insulation — loft depth, cavity fill evidence, floor and room-in-roof insulation
- Heating and hot water — boiler make and model, fuel type, cylinder, and every control
- Glazing — type, approximate age and whether units are sealed double glazing
- Lighting — the proportion of fixed low-energy fittings
- Extensions and conversions — each recorded as a separate element with its own construction
The rule that decides your rating
The software credits evidence, not assertions. If the assessor cannot see or verify something, RdSAP applies a default based on the property’s age and construction — and the default is deliberately conservative. A loft hatch blocked by boxes means defaulted insulation. No cavity-fill certificate means an assumed unfilled cavity. That is how a genuinely efficient home ends up with a mediocre band.
What to have ready
- Clear access to the loft hatch and a working light up there if possible
- Cavity-wall or loft-insulation certificates, including anything from a grant scheme
- Boiler make, model and service record, plus the installation certificate if you have it
- Window installation paperwork or FENSA certificates
- Keys for garages, outbuildings and annexes that form part of the property
- Any extension building-control completion certificates
After the visit
The assessor completes the model, quality-checks it and lodges the certificate to the national register — usually within 24 hours. You receive the rating, the estimated running costs, and a list of recommended improvements with their likely impact and indicative cost.
Book an assessment
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