New build energy assessment works differently from everything else, and the terminology trips up buyers, sellers and even some agents. Three documents matter.
SAP: the calculation behind the building
The Standard Assessment Procedure is the government methodology used to demonstrate that a new dwelling complies with Part L of the Building Regulations. It is run from the design — construction build-ups, glazing specifications, heating system, ventilation strategy — before anything is built. Existing homes use a reduced version, RdSAP, which infers from what can be observed on site. New builds use the full method, from real specifications.
Predicted Energy Assessment (PEA)
A PEA is the predicted rating, produced from the design SAP so a home can be marketed before it is finished. It exists precisely so off-plan sales can quote a rating.
What matters: a PEA is not an EPC. It cannot be lodged, it is not valid for a sale on completion, and the final rating can differ from it if the build changed. If you are buying off plan, the PEA is an indication, not a guarantee.
On-construction EPC
Once the dwelling is complete, an on-construction EPC is produced — by an assessor qualified for new build — using as-built data, and lodged on the register. This is the real certificate, and like any other domestic EPC it is valid for ten years.
The mistake that costs new-build owners money
Selling a flat bought six years ago and commissioning a fresh EPC without checking. The on-construction certificate is very often still in date, and a valid certificate is a valid certificate — there is no requirement that it be recent. Look your address up on the government register first; it is free.
You do need a new one if the original has expired, or the property has been altered enough that it no longer describes the home.
Why new builds rate so well — and one caveat
Recent flats routinely reach B, occasionally A, against D or E for the Victorian stock next door. Better fabric, better glazing, and often a communal heat network.
The caveat is that heat network: where a block is served by one, the efficiency of that network drives your rating and you cannot change it. Unusually, the heating — normally the thing an owner can improve — is out of your hands. Our Battersea and Nine Elms guide covers what that means in practice.