What is an EPC rating and does it actually matter?

An Energy Performance Certificate rates a property's energy efficiency from A (most efficient) to G (least), and is legally required whenever a home is sold or let in the UK. It is valid for ten years.

What it measures is the building's modelled efficiency — insulation, glazing, heating system, hot water, lighting — not your actual bills. It is produced by an assessor working from a standardised model, so two identical homes get the same rating regardless of how the occupants live.

Why it matters more than it used to:

Rented property has a legal minimum. Under Minimum Energy Efficiency Standards, most properties in England and Wales cannot be let with a rating below E without a registered exemption. Landlords buying a low-rated property may be buying an obligation to spend.

Lending is beginning to reflect it. Some lenders offer better rates on efficient homes, and lenders are under pressure to improve the average efficiency of their loan books.

Buyers increasingly price it in, particularly since energy costs rose sharply. A G-rated house is a running-cost liability that is visible up front.

Its real limitations:

The model is crude. It penalises some solid-wall period properties heavily and can reward things that make little practical difference. Assessors work from visual inspection and assumptions, and cannot see insulation they are not shown evidence of.

Assessments vary. The same house can get different ratings from different assessors, largely because evidence of existing work was or was not produced.

Recommendations are generic and their cost estimates are frequently unrealistic.

Practical advice: read the recommendations page rather than just the letter, and if buying, treat a poor rating as a negotiating point and a future spending forecast. Proposed rules for rented property have shifted repeatedly, so check current requirements.