RdSAP 10 official release is just days away (15th June 2025), and the energy assessment world is about to experience its biggest methodology update in over a decade. Whether you’re a Domestic Energy Assessor or property owner relying on accurate EPCs, understanding what’s changing is vital.

Here, we break down the most significant updates introduced in RdSAP 10 and explain what you need to do before the switch.

RdSAP 10 introduces a range of data enhancements aimed at improving the accuracy and value of EPCs. Many long-standing assumptions are being replaced with more precise, evidence-led inputs. Highlights include:

Several updates offer more flexibility in how we record and interpret physical building features. For instance, new wall types such as curtain walling can now be selected. Additionally, basement rooms are more clearly defined, and insulation thicknesses across walls, floors, and roofs can now be entered with more accuracy.

You now have the choice between two defined room-in-roof types, helping to distinguish between traditional style attic conversions and dormer style bungalows more effectively. This means clearer guidance for assessors and improved consistency in EPC outputs.

Rather than making assumptions on the amount of glazing, RdSAP 10 requires actual height and width measurements of all. external windows and roof lights. Frame type, frame factor, and even the presence of shutters all now play a part in how window performance is assessed.

This section has seen significant refinement. Draught lobbies, open flues, mechanical ventilation systems and more must be accounted for. In addition, where available, air pressure test results can now be entered into the RdSAP 10 software.

Instead of counting light fittings, your assessor will now record the number and type of individual lamps. The actual stored volume and standing heat loss of a hot water cylinder can be recorded if the required documentation is available.

Homes with a Solar PV battery storage systems can now benefit from more accurate reporting. Smart meters and export-capable meters are also now standard inputs. Even small-scale hydro systems can be included, with supporting evidence.

Heat pumps may now be recommended where a home is well-insulated and the technology proves cost-effective. On the other hand, recommendations like party wall insulation have been removed due to concerns around the practicality of installation.

Before 15th June:

• Continue lodging EPCs using RdSAP 9.94 (It is recommended to collect data as per RdSAP 10 requirements)
• Complete any RdSAP 10 training, get in touch if you need support with this
• Familiarise yourself with new conventions
• Review any software updates and evidence requirements

From 15th June:

• Update any survey apps to ensure they are compliant with RdSAP 10
• All new EPCs must be completed using RdSAP 10 following the new conventions, (download here)
• Any unfinished RdSAP 9.94 assessments must be re-surveyed to RdSAP 10 standards

Landlords, agents, and property owners should be aware that RdSAP 10 may slightly shift EPC results.

For example:

• Homes with modern improvements (insulation, windows, renewables) may benefit
• Properties relying on default assumptions could see lower ratings

With this in mind, it may be wise to review your current EPCs and consider a fresh assessment.

Why not get in touch for a no obligation chat!

From 15th June, all EPCs carried out by Bluewire Hub will be completed using RdSAP 10. We’ve already completed internal training, updated our systems, and are developing new CPD content for assessors.

Need Help or Advice? Whether you’re a fellow assessor or a property owner unsure about the implications of RdSAP 1o, we’re here to help. Get in touch for a no obligation chat.

With RdSAP 10 bringing greater scrutiny to EPC accuracy and ratings, it’s more important than ever to engage a reputable, experienced Domestic Energy Assessor who can confidently manage your property’s energy performance and protect your investment.

Contact us today to ensure your assets are in expert hands. We’re here to provide expert advice and support every step of the way—get in touch to discuss how we can help you navigate these important changes with confidence.

Here are some affordable products that can help you start saving energy immediately:

1. Energy-Efficient LED Bulbs: Amazon Link
2. Smart Thermostat: Amazon Link
3. Draught Excluder Strips: Amazon Link
4. Loft Insulation Roll: Amazon Link