Plain English answers to the terms UK builders and assessors actually meet on site
Building Regulations are full of letters, numbers, and acronyms. Part L, L1A, Appendix B, SAP, BREL, OCDEA, EPC, FHS - the list goes on. It's not helpful when you're trying to get a plot signed off before handover.
This glossary explains each term in plain English. Short definitions. No jargon. No waffle. If you've got an assessor asking for "the Appendix B evidence" and you want to know what that actually is before replying, you're in the right place.
Part L is the energy efficiency section of the UK Building Regulations. It sets how much energy a new or altered building can use, and how you have to prove it on site.
Appendix B is the part of SAP that says exactly which photos you need to prove a new home was built as designed. It's where the photo evidence requirements actually live.
SAP is the Government's method for calculating how energy-efficient a new home is. It turns a building design into a single score used for Part L sign-off and the EPC.
A DEA is the accredited professional who produces Energy Performance Certificates for existing homes being sold or rented. Not the same as an OCDEA, despite the similar letters.
An OCDEA is the assessor who signs off new-build homes for Part L. They run the SAP, review your Appendix B photos, and produce the BREL report. The one builders deal with on site.
BREL is the report the OCDEA produces to prove a new home complies with Part L. It bundles the SAP results, the photographic evidence, and the assessor's sign-off into one document.
The Future Homes Standard is the Government's plan to make new UK homes zero-carbon-ready. Tighter Part L, stricter evidence expectations, no new gas boilers. The transition is live now.
