What is an EPC?

The Energy Performance Certificate - how a UK home's predicted energy efficiency gets graded

An EPC - Energy Performance Certificate - grades a dwelling's predicted energy efficiency on a scale from A down to G, alongside a figure for predicted annual running costs and a list of recommended upgrades. Any UK home being sold, rented, or finished as a new build needs a valid one, produced by an accredited assessor and lodged on the Energy Performance of Buildings Register.

It's the A-G coloured chart most homeowners recognise from estate-agent listings. For builders and assessors, it's the public-facing output of the SAP calculation and the thing the finished home carries for the next decade.

What's on an EPC

  • The current energy efficiency rating - a number out of 100, mapped to a band from A (most efficient) to G (least)
  • The potential rating - what the home could achieve after the recommended improvements
  • Estimated annual energy costs for heating, hot water and lighting
  • Environmental impact - a separate A-G rating based on CO₂ emissions
  • A list of recommendations - typical suggestions range from better loft insulation through to solar PV or a heat pump
  • Assessor details and accreditation body
  • Reference number for the lodged certificate

Who issues an EPC

An accredited assessor. For existing dwellings that's a DEA (Domestic Energy Assessor) running RdSAP. For new builds it's an OCDEA (On Construction Domestic Energy Assessor) running full SAP, usually as part of the BREL report at handover. Accreditation is held through Elmhurst Energy, Stroma Certification, Sava, Quidos or ECMK.

When an EPC is required

UK law requires a valid EPC when:

  • A dwelling is sold
  • A dwelling is let to a new tenant
  • A new-build dwelling is completed and handed over
  • A dwelling undergoes substantial renovation that triggers a new assessment
  • A non-dwelling is marketed for sale or let (produced via SBEM, not SAP)

For rentals in England and Wales, there's also a minimum energy efficiency standard - currently band E - that a landlord cannot legally let below without an exemption.

How long an EPC is valid

Ten years from the date of issue. After that the home needs a fresh assessment before it can next be sold or let. Substantial renovation work should prompt a new EPC sooner so the certificate reflects the improved performance.

EPC for a new build vs an existing home

Different routes, same coloured chart:

  • New build: the OCDEA runs full SAP based on the design and as-built evidence, including the Appendix B photographs. The EPC is a by-product of that work and is lodged once the BREL signs off Part L.
  • Existing home: a DEA visits the property, records what's actually there, and runs RdSAP (a reduced-data version of SAP). It's a quicker, observation-based process that doesn't require design drawings.

The two processes produce certificates that look identical on the front, but the methodology behind them differs. An EPC from a new-build is generally more accurate because it's rooted in design data and photographic evidence of what was installed.

Buildsnpper produces the Appendix B evidence package that feeds the as-built SAP and, ultimately, the new-build EPC. Section-by-section capture, GPS and timestamp on every photo, straight to your OCDEA. From £6.67 per month, 14-day free trial. See how it works.

Frequently asked questions

What does EPC stand for?

Energy Performance Certificate. It's the official UK document grading a dwelling's predicted energy efficiency from A (most efficient) to G (least) and estimating annual energy running costs.

How long is an EPC valid?

Ten years from the date it was lodged on the Energy Performance of Buildings Register. A fresh assessment is required before the home can next be sold or let.

Who can produce an EPC?

An accredited Domestic Energy Assessor (DEA) for existing dwellings, or an accredited OCDEA for new builds. Accreditation is held through one of the recognised schemes - Elmhurst Energy, Stroma Certification, Sava, Quidos or ECMK.

What does the EPC rating mean?

The rating is a score from 1 to 100+, banded from A (most efficient, typically 92+) down to G (least efficient, 1-20). Most existing UK homes fall in the D or E band; new builds under current Part L rules typically achieve B or high C, with the Future Homes Standard pushing ratings higher still.

Does a new-build automatically get an EPC?

Yes. As part of the Part L sign-off, the OCDEA lodges an EPC on the Energy Performance of Buildings Register. You can't legally hand over a new dwelling without one.

What happens if an EPC expires before the home is sold?

You need a new assessment before marketing or completing the sale. A DEA visit is quick and typically costs between £60 and £120 depending on the property.

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