EPC changes 2025 – get ready for RdSAP 10
RdSAP 10 refers to version 10 of the Reduced Data Standard Assessment Procedure (RdSAP), the method used in the UK to assess the energy performance of existing residential properties. It is a simplified version of SAP (Standard Assessment Procedure), designed specifically for older or already-built homes where full construction details may not be available.
Significant changes from 15th June
RdSAP 10 represents the most substantial update to the assessment methodology in years, requiring assessors to gather more detailed information during property visits. It will introduce expanded ventilation options, more detailed window measurement, noting wall types and constructions, the inclusion of air pressure test results, among other new metrics.
Previously, software limitations required assessors to make assumptions, resulting in some property details being recorded inaccurately. With RdSAP 10, however, assessments are significantly more precise, allowing for detailed data and supporting evidence to be submitted.
Why is the update to the RdSAP methodology so important?
The introduction of RdSAP 10 is a critical step in the UK’s efforts to modernise its housing stock and reduce energy consumption. As the government tightens regulations and incentives around energy efficiency, accurate energy assessments are becoming increasingly important. They not only influence property values but also impact homeowners’ and landlords’ responsibilities to achieve certain energy ratings.
With the 15th June marking the official release date of RdSAP 10, now is the perfect time to make sure you’re up to speed with the coming changes.
The key updates
Room in the roof
RdSAP 10 introduces two distinct ‘room in roof’ types, giving assessors the flexibility to choose between a simplified or detailed assessment (suitable documentation required) method for each.
This update also brings a requirement for additional measurement, such as the dimensions of gable walls and where applicable, common walls, to better reflect the variety in construction styles.
Windows
This is one of the biggest changes for assessors, as now all windows will have to be measured. Additional options will also be made available, such as for frame types and permanent shutters. The number of glazing age categories have also increased to encompass varying regional standards and installation dates.
Ventilation (including air pressure test results)
Ventilation options have been significantly expanded in RdSAP 10, with the inclusion of several new features and enhanced data collection requirements. These now cover elements such as open fireplaces, chimneys, and flues, among others. Support for mechanical ventilation systems has also been greatly improved, with a greater number of input options.
Air pressure test results
Air pressure test results can now be included provided documentary evidence is available. Incorporating these rest results into the building performance assessment can lead to a better representation of a building’s energy efficiency.
Walls, roof and floors
RdSAP 10 offers improved accuracy in assessments by expanding options for walls, roofs, and floors. Assessors can now specify two wall types per building part and input detailed insulation data, including actual thickness and, where supported, thermal conductivity.
Roof assessments include a wider range of insulation thicknesses and a new option for unheated or non-residential spaces, eg. commercial units above flats. Floor insulation can also be recorded with specific thicknesses for retrofitted measures.
Other notable updates
- Lighting: The number of bulbs must now be collected as well as the fittings, identifying how many are LEDs or CFLs.
- New technologies: PV battery storage, diverters, and even small-scale hydro generation are now recognised.
- Water heating: It is now possible to account for the cylinder size and any heat loss if documentary evidence is available.
- Heated basements: More detail is included and there are additional construction options to choose from, with specific u-values applied to walls and floors to better represent the space.
Other forthcoming changes to recommendations will include:
- Heat pumps to be recommended more regularly for homes that are suitably insulated and where an upgrade is cost-effective.
- PV diverters and battery storage will be offered but only when PV systems are already present.
NicheCom welcomes these methodology updates that have been developed in part by the BRE, the government and industry bodies such as our own EPC accreditation partner, Elmhurst Energy.
The updated assessments will provide a more accurate reflection of the energy efficiency of our homes, but will require more time to be spent on site by a DEA gathering additional property information.
If you have any queries about the changes coming in June, contact us on 0118 977 0690 or email info@nichecom.co.uk.