RdSAP10
Changes & Assessor Guidance
Learn about the latest RdSAP10 updates, methodology changes, and guidance for domestic energy assessors.
Introduction
Going live on 15th June 2025, RdSAP10 represents the largest change to the methodology in roughly 13 years. The changes are part of the Government’s aim of eliminating fuel poverty, lowering carbon emissions and creating healthier and more comfortable dwellings.
The changes will improve the accuracy of assessments and ensure that modern technologies have become more commonplace over the last ten years represented.
Whilst in Quidos’ opinion it does not resolve all the industry’s difficulties, it should be seen as an exciting and much-needed steppingstone towards the Home Energy Model, EPC reform and minimum energy efficiency standards (MEES) changes we expect to see in the next few years.
So, what’s changing…
Key Changes in RdSAP10
Explore the main updates introduced in the RdSAP10 methodology. Each section below outlines specific changes assessors need to understand – from glazing measurements to ventilation, insulation, and more.
All windows must now be measured in RdSAP10. This brings the methodology in line with SAP, non-domestic and retrofit. As part of the changes to measuring windows, there are new glazing age bands for different window types and the ability to enter the presence of shutters.
Information needed to be collected on windows:
Draughtproofed? /Orientation/Glazing Type/Glazing location/Wall location/Dimensions/Presence of Shutters
Roof rooms have had a major overhaul in RdSAP10. Roof rooms now have two types depending on the type of build. Type 1 is a “true roof room” and type 2 is where there is a common wall (more of a short storey). When selecting these you have additional information to collect such as the dimensions for the gable walls and common walls.
RdSAP10 brings about numerous changes for walls. Walls see the introduction of new wall types (curtain walls, basement walls). It also sees the ability to add two alternative walls per building part. Wall insulation thicknesses see an upgrade with more thicknesses to choose from and the ability to select the thermal conductivity of solid walls.
For roofs, there is a new roof type for “non-residential or unheated spaces” above a property and more precise insulation thicknesses have also been introduced.
For floors, there is a new floor type in “basement floor” and the introduction of more precise insulation thicknesses.
The exact cylinder size can now be identified in RdSAP10. This alongside the ability to input declared cylinder heat loss allows for a more accurate water heating entry.
Ventilation in RdSAP10 has been brought in line with full SAP and sees the introduction of multiple new mechanical ventilation options as well as data collection being needed for open fireplaces, chimneys, extract fans, passive stacks etc.
Mechanical ventilation can also be selected from the database.
Finally, air pressure test results can be included. This allows for the properties building performance to be measured much more accurately and will likely have a significant impact on ratings.
In line with upgrading building regulations a new age band has been created for all countries. This will allow the modern properties to have the correct assumptions made about them in line with the building regulations from when they were built.
PV batteries and PV diverters can now be accounted for and selected in RdSAP. These additions come alongside recommendations for both too.
A less common, but no less important technology, small-scale hydro generation, is now able to be recognised within the methodology.
In the previous version of RdSAP, Assessors identified the total number of light fittings. Going forward, in RdSAP10, Assessors must identify number of light bulbs. From here you also need to identify the type between incandescent, CFL and LED.
RdSAP10 finally sees the introduction of a heat pump recommendation. This recommendation is only given on “fairly insulated” properties and where the rating to install a heat pump is better than that of a gas boiler.
The other recommendations added are PV batteries and diverters, which will be recommended when there aren’t any.
Communicating Changes to Your Clients
Not sure how to explain RdSAP10 to your customers?
We’ve put together a simple guide that outlines what’s changing, why it matters, and how it affects the assessment process – perfect for sharing with clients or using in conversations.
RdSAP10 Resources
Access essential tools and guidance to help you confidently transition to RdSAP10.
Below you’ll find the latest conventions, answers to frequently asked questions, and a downloadable data collection form to support your assessments.
Conventions
Download the latest set of RdSAP10 Conventions to ensure your assessments follow current guidelines. These conventions clarify common scenarios and support consistent decision-making.
FAQ's
We’ve compiled the most frequently asked questions about RdSAP10, covering everything from software changes to assessment rules.
Data Collection Form
Use this updated data collection form to make sure you’re capturing all the necessary inputs for RdSAP10-compliant EPCs.
Additional Information
For more information on the changes to RdSAP10, please head to our support log where you can access a full RdSAP10 training pack, which includes:
- Technical bulletins
- RdSAP10 changes free CPD module
- RdSAP10 conventions free CPD module
- Video software walkthroughs
- Much more….
If you have any questions, please contact support@quidos.co.uk
Get in touch
If you have any queries or concerns do not hesitate to get in touch and one of our team will be happy to help.