RdSAP 10: A New Era for EPCs and Sustainable Buildings
At LP Energy, we’ve always championed the role of data-driven insights in shaping a more energy-efficient built environment.
The recent overhaul of the Reduced Data Standard Assessment Procedure (RdSAP) to version 10, which came into effect earlier this month on 15 June 2025, marks a pivotal moment in the evolution of Energy Performance Certificates (EPCs) in the UK.
This update is not just a technical revision—it’s a strategic shift that aligns EPCs more closely with real-world energy performance and the UK’s net zero ambitions.
Why RdSAP 10 Matters
EPCs have long been a cornerstone of the UK’s energy efficiency strategy, providing a standardised measure of a building’s energy use and carbon emissions. However, the previous RdSAP methodology had limitations, particularly in its ability to reflect modern technologies and diverse property types. RdSAP 10 addresses these gaps with a suite of enhancements that bring greater accuracy, transparency, and relevance to EPC assessments.
For energy efficiency and sustainability consultancies like LP Energy, these changes are a welcome development. They empower us to deliver more precise advice, support better retrofit decisions, and ultimately help clients reduce both carbon footprints and energy bills.
“At LP Energy, we see this as an opportunity to engage with clients more proactively, to deliver a more tailored and strategic service.
Whether that is advising landlords on compliance with Minimum Energy Efficiency Standards (MEES), supporting property stakeholders with retrofit plans, or helping developers future-proof new builds, the enhanced EPC system strengthens the case for sustainable investment.”
– Lee Pasifull, Managing Director
Key Changes
The most significant updates in RdSAP 10 include:
- Expanded Data Collection: Assessors now collect over 400 data points (an additional 150). This includes detailed information on insulation, heating controls, renewable technologies, and building fabric, resulting in a more nuanced and accurate EPC rating.
- Improved Modelling of Heating Systems: RdSAP 10 introduces better modelling for low-carbon heating systems such as heat pumps and district heating. This is crucial as the UK transitions away from fossil fuel-based heating.
- Recognition of Modern Technologies: The new methodology accounts for technologies like battery storage, smart thermostats, and mechanical ventilation with heat recovery (MVHR), which were previously overlooked or poorly represented.
- Increased Accuracy Floor Area Calculations: EPCs now use internal floor area, rather than total floor area, aligning with other industry standards and improving comparability.
- Updated Default Values: Where specific data is unavailable, RdSAP 10 uses more realistic default values, reducing the risk of under/over estimating a property’s performance.
These changes mean that EPCs will now better reflect the actual energy performance of properties, especially those that have undergone efficiency improvements.
Implications for the Market
According to the latest government statistics, 466,000 EPCs were lodged in England and Wales in Q1 2025 alone*.
With RdSAP 10 now in force, these certificates will offer more reliable insights for homeowners, landlords, and policymakers alike. For property professionals, the changes may initially cause some disruption.
EPC ratings could shift, meaning that some properties may see their ratings drop due to more stringent modelling parameters, while others may benefit from recognition of previously unaccounted-for upgrades. However, this recalibration is essential for ensuring that EPCs remain a credible tool for driving energy efficiency.
