An Introduction to EPCs and How They Affect Landlords

Photo by Gleren Meneghin on Unsplash

An EPC — or Energy Performance Certificate — is an assessment of a property’s energy efficiency. It considers several key elements, including the central heating system, glazing, insulation (in the walls, roof, and ground floor), water heating, ventilation, and the building’s age, to name just a few.

The assessment is more involved than simply observing these features. Assessors use measuring devices to calculate the floor area of each storey, including any extensions or connected conservatories. Since the introduction of RDSAP 10 in June 2025, assessors are now required to measure all glazed openings and input them into the software. This update allows different types and ages of glazing to be recorded at the same time, resulting in a more accurate EPC.

If you’re a landlord, it’s important to provide any relevant documentation on the day of the assessment. This could include cavity wall guarantees, FENSA certificates for windows, or contractor invoices that specify the type and location of insulation. These documents are essential for an accurate rating. For instance, if you’ve installed internal wall insulation on all heat-loss walls, the assessor needs written proof from the contractor — otherwise, they must assume it isn’t there.

While this might feel frustrating, EPCs are strictly evidence-based. What isn’t visible or verifiable through photos or documents on the day cannot be included. Please note an assessor cannot accept photographs from you or a third party.

Why is this evidence important? It comes down to quality assurance. EPCs are randomly audited by accreditation scheme providers. To pass an audit, an assessor must supply enough photographic and documentary evidence to allow an auditor to recreate the EPC from scratch. If areas like lofts or walls can’t be accessed, for example, if there’s no loft hatch or insulation is hidden behind unremovable panels — the assessor must record those elements as uninsulated. This follows the RDSAP conventions, which govern how EPCs are carried out.

And remember: EPCs are non-intrusive. Assessors cannot use tools or remove fixed panels. If your hot water cylinder or immersion heater is behind a locked cupboard or fixed board, it won’t be included in the assessment unless it’s made accessible beforehand. The same goes for boarded lofts where insulation can’t be seen or measured.