The Energy Performance Certificate (EPC) system will see the introduction of RdSAP 10 – an update to the methodology that underpins domestic energy assessments in existing homes.
The changes are the most significant in over a decade and are expected to improve the accuracy of EPCs, better reflect how homes are used, and help inform decisions on energy efficiency.
Key changes in energy assessments include expanded data collection, more accurate assessment of heating systems, improved floor area and insulation modelling, and better treatment of flats and mid-terrace properties.
Landlords will need to be more proactive in maintaining and providing evidence of energy improvements.
EPCs are already a regulatory requirement for letting properties, and minimum standards (currently EPC E in England and Wales) mean that an inaccurate or lower-than-expected rating could block a tenancy.
The changes mean residents can have greater confidence in the accuracy of EPCs.
Tenants may use this information to identify more energy-efficient homes, potentially lowering their energy bills.
Homeowners looking to sell may find that a more accurate EPC helps them highlight energy efficiency improvements they've made—provided they can evidence them.
The version set to be introduced in June 2025, RdSAP 10, incorporates new data inputs, revised assumptions, and structural changes designed to bring EPCs closer to reality.