RdSAP 10: Major EPC Changes Coming
The largest update to Energy Performance Certificates in 13 years
What is RdSAP 10?
RdSAP 10 (Reduced data Standard Assessment Procedure version 10) is the new methodology for calculating Energy Performance Certificate (EPC) ratings for domestic properties.
This is the most significant update since RdSAP 9.93 was introduced in 2012, bringing substantial changes to how properties are assessed and rated for energy efficiency.
Major Changes in RdSAP 10
Window Assessments
More detailed window specifications including frame types, glazing quality, and installation methods. Triple glazing now receives enhanced recognition.
- Improved glazing categorization
- Better credit for modern window technology
- More accurate U-value calculations
Building Envelope
Enhanced assessment of insulation levels, thermal bridging, and air tightness. More detailed evaluation of wall construction and roof insulation.
- Updated U-value standards
- Improved insulation recognition
- Better thermal bridge calculations
Heating Systems
Updated efficiency ratings for modern heating systems including heat pumps, hybrid systems, and smart heating controls.
- Better recognition of heat pump technology
- Updated boiler efficiency ratings
- Enhanced smart control credits
Renewable Energy
Improved calculations for solar PV, solar thermal, and battery storage systems with more accurate generation estimates.
- Better solar generation modeling
- Battery storage recognition
- Updated renewable energy factors
Ventilation
More comprehensive assessment of ventilation systems including mechanical ventilation with heat recovery (MVHR).
- MVHR system recognition
- Improved ventilation credits
- Better air quality considerations
Lighting
Updated assumptions reflecting the prevalence of LED lighting and smart lighting controls in modern properties.
- LED standard assumptions
- Smart lighting recognition
- Updated energy consumption models
How Will This Affect Your Property Rating?
Properties Likely to See Improved Ratings
- Properties with modern triple-glazed windows
- Homes with heat pumps or hybrid heating systems
- Properties with solar PV and battery storage
- Well-insulated modern builds
- Homes with MVHR systems
- Properties with smart heating controls
Properties That May See Lower Ratings
- Older properties with single glazing
- Homes with older, less efficient boilers
- Properties with poor insulation
- Buildings with high thermal bridging
- Properties relying on electric storage heaters
What Property Owners Need to Know
Existing EPCs Remain Valid
If your property has an EPC issued before 15 June 2025, it remains valid for its full 10-year term. You don't need to get a new one until it expires.
New Assessments Use RdSAP 10
All EPCs conducted from 15 June 2025 will automatically use the new RdSAP 10 methodology. There's no choice to use the old system.
Longer Assessment Time
Due to the increased detail required, RdSAP 10 assessments may take slightly longer to complete on-site.
More Accurate Ratings
The new system provides a more accurate reflection of your property's actual energy performance and running costs.
Updated Recommendations
Improvement recommendations will be more tailored and relevant to modern energy efficiency measures.
No Price Increase
Despite the additional complexity, our EPC pricing remains competitive at £60 per property.
RdSAP 10 Timeline
RdSAP 9.93 (Current System)
All EPCs use the current methodology that has been in place since 2012.
RdSAP 10 Launch
New methodology becomes mandatory for all domestic EPCs in England and Wales.
New Standard
All new EPCs use RdSAP 10. Existing EPCs remain valid until their expiry date.
How to Prepare Your Property
1. Gather Documentation
Have ready any certificates or receipts for:
- Window installations and glazing specifications
- Boiler service records and efficiency ratings
- Insulation installation certificates
- Solar PV installation documents
- Heat pump specifications
2. Consider Upgrades
To maximize your rating under RdSAP 10, consider:
- Upgrading to an A-rated condensing boiler
- Installing or upgrading loft insulation
- Adding smart heating controls
- Upgrading to double or triple glazing
- Installing solar PV panels
3. Timing Your EPC
Consider the timing of your EPC:
- If selling soon, current EPC may be sufficient
- If making improvements, wait until after completion
- New EPCs from 15 June 2025 valid for 10 years
- Allow time for energy improvements before assessment
Need an EPC Under the New RdSAP 10 System?
Our assessors are fully trained and ready for RdSAP 10
Still have questions about RdSAP 10?
Call us on 01634 944203