RdSAP 10 – Update to the EPCs

The Energy Performance Certificate (EPC) process in England is undergoing a significant update with the introduction of RdSAP 10—Reduced Data Standard Assessment Procedure version 10. This new version represents changes in the way domestic energy assessments are conducted for existing homes and will come into force in June 2025.

RdSAP 10 – Key Updates to the EPC Methodology

RdSAP is the Government-approved methodology used to produce EPCs for existing dwellings. It uses standard assumptions to generate a rating that reflects the energy efficiency of a property. Version 10 marks the first major update since RdSAP 2012 and aligns with broader government objectives to improve energy efficiency, reduce carbon emissions, and inform retrofit strategies.

Key Features and Changes in RdSAP 10

RdSAP 10 allows assessors to collect more detailed property data, by improving the precision of the assessment model.

There will be a more nuanced categorisation of heating types, controls, and fuel types (e.g. heat pumps, hybrid systems) for a more accurate efficiency score, greater detail on wall, floor, and roof construction types, especially in older and hard-to-treat properties.

There will also be reference to updated input options for solar PV, battery storage, smart heating controls, and electric vehicle charging points.

Implications for Property Professionals

Letting & Estate Agents may see a shift in EPC ratings as RdSAP 10 which may produce different outcomes than its predecessor—potentially affecting marketing, lettability, and minimum standards compliance.

Landlords should be aware that properties previously close to the minimum EPC rating (E) threshold may be reassessed differently under RdSAP 10.

Retrofit Advisors & Energy Assessors will require training on the new methodology and software tools. Additional time may be needed for site visits due to the enhanced data collection requirements.

Timeline and Transition

June 2025: Formal rollout of RdSAP 10.

Assessors will be required to use RdSAP 10 for all new EPCs from the date of implementation.

Existing EPCs will remain valid until expiry (10 years from issue), but any reassessment after June 2025 will use the new method.

Further Guidance

For authoritative guidance:- Department for Energy Security and Net Zero (DESNZ): https://www.gov.uk/government/organisations/department-for-energy-security-and-net-zero

Credit; Susie Crolla (GLM)