What it is
The SAP EPC — the new-build EPC — is the final output of the as-built SAP calculation. Where the EPC on an existing home comes from a survey and the reduced-data version of SAP, a new dwelling’s certificate is produced from the full as-built SAP — the same model that demonstrated Part L compliance — and lodged on the national register. It is required before Building Control can issue the completion certificate, which makes it a critical-path item at the end of every project.
The five-day rule
The Energy Performance of Buildings Regulations require that, where a building is erected, the person carrying out the work gives an EPC to the owner and notifies the local authority of its registration reference not later than five days after the work is completed. The certificate can only be produced by an accredited on-construction domestic energy assessor — a specific accreditation for new dwellings; an assessor accredited for existing homes cannot lodge it.
Because we produce the EPC from the same as-built calculation we prepared for Building Control, the certificate and the compliance report always agree — which is not a given when two different people produce them.
What we need to lodge your EPC
To finalise the as-built calculation and lodge the EPC, we need:
- Confirmation the as-built spec matches the design (or details of any changes), including psi values and any scheme construction details used
- The Part L photographic evidence, reviewed against the specification
- Make and model of the heating system installed, plus cylinder capacity if fitted
- Confirmation of heating controls
- Percentage of low-energy lighting
- Full address and postcode — including which plot is which on multi-plot sites
- Air test certificates
- Evidence of any renewables installed — PV array size, inverter, or the heat pump’s make and model
Get this list to us early and the EPC will not hold up your sign-off. The two that most often do are the air test certificate — book the test into the programme, not after it — and the plot addresses, which need to exist on the address register before a certificate can be lodged against them.
What is on it
The SAP rating, a score from 1 to 100 for energy cost performance, and its band from A to G — a dwelling built to Part L 2021 typically lands in band B, the best in A. The environmental impact rating, the estimated annual energy costs, and a summary of the dwelling’s fabric and services. Every flat in a block gets its own certificate against its own address, from its own as-built calculation.
SAP EPC vs RdSAP EPC
There are two ways a domestic EPC gets produced, and they are not interchangeable. An RdSAP EPC — the one on an existing home — comes from a survey by a domestic energy assessor using the reduced-data version of SAP, which infers what it cannot see from the building’s age and type. A SAP EPC comes from the full SAP model of a dwelling that did not exist to be surveyed, produced by an on-construction domestic energy assessor (OCDEA) from the as-built specification and the site evidence. Every newly erected dwelling gets a SAP EPC, and so does a dwelling created by conversion where the regulations require one. An extension to an existing home does not need an EPC at all — the trigger is the construction of a new dwelling, a sale or a letting — so the SAP we run for an over-glazed extension is a compliance calculation only.
The predicted EPC is not the EPC
At design stage the SAP produces a Predicted Energy Assessment: the expected rating and band, used to market the home off-plan. It is not lodged and it carries no legal weight; the certificate proper can only be produced from the as-built calculation once the dwelling is complete. Buyers, lenders and sales teams sometimes treat the two as the same document. They are not, and where the specification changed on site the as-built rating can land a point or two either side of the prediction.
When the as-built differs from the design
The as-built SAP has to describe the dwelling that was built, not the one that was drawn. So before the EPC is lodged we update the model for whatever changed — a different boiler or heat pump, a smaller PV array, a window specification swapped at order, junction details that were not built as the calculated Ψ-values assumed — and we put the tested air permeability in place of the design assumption. Then the compliance tests are run again. If a change has pushed the as-built dwelling over its target, it is fixed before lodgement: better lighting, a top-up to the PV, a re-test after remedial sealing where the air test came in high. The BREL compliance report Building Control receives is produced from that same final model, which is how the EPC and the compliance report always agree.
How long it lasts, and what it costs
A new-build EPC is valid for ten years, or until a newer certificate is lodged for the address, and it is the certificate the home is sold and let on for that period. It is quoted with the as-built SAP rather than as a separate certificate — the calculation is the work and the lodgement is its last step — so ask for the design-stage SAP, the as-built SAP and the EPC together. Where we did not produce the design-stage SAP we can still lodge the EPC, but we have to build the as-built model ourselves first. Where a scheme also needs a water calculation, an air test and sound testing, the Compliance Pack prices all of it as one job.
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Common questions
What is a SAP EPC?
The Energy Performance Certificate for a newly built dwelling. Unlike the EPC on an existing home, which is produced from a survey using the reduced-data version of SAP, a new-build EPC is produced from the full as-built SAP calculation — the same model that demonstrated Part L compliance — and lodged on the national register by an accredited on-construction domestic energy assessor.
When does the new-build EPC have to be produced?
Within five days of the building work being completed. The Energy Performance of Buildings Regulations require the person carrying out the work to give the EPC to the building's owner and to notify the local authority of its registration reference in that window. Building Control cannot issue the completion certificate without it, which makes it a critical-path item at the end of every project.
Who can produce a new-build EPC?
Only an accredited on-construction domestic energy assessor — the accreditation for producing EPCs from full SAP on new dwellings. A domestic energy assessor accredited for existing homes cannot lodge it. Ours are accredited, and we lodge the EPC from the same as-built SAP we produced for Building Control, so the two never disagree.
What is the difference between the SAP rating and the EPC band?
The SAP rating is a score from 1 to 100 for the dwelling's energy cost performance; the EPC band is that score expressed as a letter, A to G. A new dwelling built to Part L 2021 typically lands in band B, with the best in band A. The certificate also shows the environmental impact rating and the estimated energy costs.
Why is my EPC being held up?
Almost always a missing piece of as-built information: the air test certificate, the heating make and model, confirmation of a specification change, or a plot address that has not yet been registered. The EPC cannot be lodged from the design specification — it has to reflect what was built — so the checklist on this page is worth working through before the last week.
Does each flat get its own EPC?
Yes. Every dwelling has its own certificate with its own address, produced from its own as-built calculation. A block of twelve flats is twelve EPCs, which is why we ask for a plot-to-address schedule early.
How long is a new-build EPC valid for?
Ten years from the date it is lodged, or until a newer certificate is lodged for the same address — the register always shows the latest one. The certificate belongs to the dwelling, not the owner, so it stays valid through a sale or a letting within that period; most new homes are sold and let on the original as-built EPC.
What is a predicted EPC (PEA)?
A design-stage document produced from the design SAP and used to market a home off-plan before it is built. It is not lodged on the register and it is not the EPC — the certificate itself can only be produced from the as-built calculation once the dwelling is complete. If the specification, the air test result or the plot address change between the two, the as-built rating can differ from the predicted one.
Can you lodge the EPC if another assessor did the design-stage SAP?
Yes, but the certificate is lodged under our accreditation, so we produce the as-built SAP model ourselves — from the drawings, the specification, the air test and the site evidence — rather than sign off someone else's file. That costs more than the certificate alone would, which is why having one assessor do the design stage, the as-built and the EPC is the cheaper route.
How much does a SAP EPC cost?
It is quoted with the as-built SAP rather than as a separate certificate, because the EPC is the last step of the same calculation. Ask for the design-stage SAP, the as-built SAP and the EPC in one quote; for a block of flats it is priced per dwelling, since each has its own calculation and its own certificate.