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02 · Building Regulations · Part L

On-construction EPC

When a new home is finished, or a building is converted into a new home, an on-construction Energy Performance Certificate (EPC) has to be produced from the as-built SAP calculation and lodged on the government register. Building control will want to see it before signing the work off.

DWGuide by Dan Wallis · Updated 27 September 2026

This guide covers the rules in England. See Wales, Scotland and Northern Ireland.

66 on-construction energy assessorsPart L
Who needs oneAnyone building a new home or converting a building into homes
Who can do itAn On-Construction Domestic Energy Assessor (OCDEA)
WhenAt completion, after the air test and as-built SAP

66 on-construction energy assessors listed across the UK

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Find on-construction energy assessors by region

London (15) South East (7) East of England (10) South West (6) West Midlands (11) East Midlands (7) Yorkshire and the Humber (3) North West (14) Northern Ireland (5)

National providers (47)

Regional providers (check they cover your area) (1)

How it fits with the rest of your sign-off

  • Your assessor updates the design-stage SAP with what was actually built, including the air test result.
  • They produce the Building Regulations England Part L (BREL) report and the on-construction EPC.
  • The EPC is lodged on the national register and shared with building control and the buyer or occupier.

Evidence you will need

  • The air tightness test certificate
  • Details of the heating, hot water, ventilation and any solar PV actually installed
  • Photographs showing how key details were built, as required under the 2021 Part L
  • Any changes from the original design, such as different windows or insulation

In Wales, Scotland and Northern Ireland

This guide describes the rules in England. Building regulations are devolved, so here is how on-construction EPC works in the rest of the UK.

Wales

The process is the same as in England. Wales shares England’s EPC register, and the as-built report is the Welsh BRWL rather than BREL, with photographic evidence of how key details were built.

Scotland

Scotland has its own register, the Scottish EPC Register, and the EPC must be produced by a member of an approved organisation. It must also be fixed inside the new home, often in the meter cupboard. New-style Scottish EPCs are now due from 30 April 2028.

Northern Ireland

An accredited assessor lodges the EPC on the Northern Ireland register, which now runs through the same gov.uk service as England and Wales. The builder must give it to the owner within 5 days of completion.

Common questions

Is an on-construction EPC the same as a normal EPC?

It is the same certificate, but it is produced from a full SAP calculation by an OCDEA, not from a survey of an existing home.

Can I sell or let the home without it?

No. A new home needs a valid EPC before it is marketed for sale or rent.

Who should I book?

Usually the same assessor who did your design-stage SAP, because they already have the model and can update it quickly.

When is the on-construction EPC done?

At completion, after the air test and the as-built SAP calculation. Building control will want to see it before signing the work off.

What will the assessor need from me?

The air tightness test certificate, details of the heating, hot water, ventilation and any solar PV actually installed, photographs of how key details were built, and any changes from the original design, such as different windows or insulation.

New to the jargon? See our glossary of terms, from air permeability to TrustMark.