Why Landlords Need to Prepare for the Biggest EPC Overhaul in a Decade
From 15 June 2025, EPC assessments move to RdSAP 10, demanding precise data on glazing, insulation, heating systems and smart controls. This overhaul promises fairer, more accurate ratings—especially for flats and mid-terraces—but also means longer inspections, higher fees and the need for impeccable documentation to safeguard your tax and ROI.
If you’re a landlord, you’ve probably grown used to Energy Performance Certificates (EPCs) ticking along in the background every ten years. But on 15 June 2025, the introduction of RdSAP 10 will transform EPC assessments from a largely assumption-driven process into one demanding concrete proof and far more data collection. These changes promise more accurate, fairer ratings - especially for flats and mid-terrace homes - but they also herald extra paperwork, longer inspections, and, very likely, higher costs.
What Is RdSAP 10 and Why Is It Here?
The Reduced Data Standard Assessment Procedure (RdSAP) underpins EPC ratings for existing UK homes. The update to RdSAP 10 reflects a decade’s worth of new building methods, technologies, and real-world data, ensuring certificates better mirror how properties actually perform.
Key objectives of RdSAP 10 include:
- Improved accuracy through more detailed measurements and evidence.
- Fairer treatment of flats and mid-terrace homes, which often suffered under old default assumptions.
- Enhanced guidance for low-carbon technologies, helping landlords and tenants make smarter retrofit decisions.
The Major Assessment Changes Landlords Must Know
Expanded Data Collection
Assessors will now record every window, noting frame type and condition, rather than sampling.
Glazing, wall insulation thickness, and thermal conductivity values (where documented) must be logged.
Roof-room construction, including party-wall details, and ventilation sources—from open fireplaces to extractor fans—are explicitly captured.
Evidence-Based Heating Ratings
Instead of default efficiencies, assessors will prioritise manufacturer data, model numbers, and receipts for boilers, heat pumps, and smart controls.
Unverified systems will default to lower efficiency ratings, potentially dragging your EPC grade down if documentation is missing.
Refined Floor Area & Insulation Modelling
Improved algorithms will calculate heat loss more precisely, using exact floor-plan measurements and documented insulation depths, rather than generic U-value tables.
Better Treatment of Flats & Terraces
RdSAP 10 adjusts thermal bridging and heat-loss assumptions for mid-terrace and flat properties, which were often penalised under the old methodology. Early reports suggest some of these homes may see improved EPC scores as a result.
Recognition of Renewable & Smart Technologies
Solar PV, battery storage, PV diverters, and small-scale hydro systems can now be included—if evidence is provided—improving ratings for eco-upgraded properties.
Smart heating controls and advanced insulation systems gain formal acknowledgment, aligning certificates with modern efficiencies.
What This Means for Your Bottom Line
- Longer, More Detailed Inspections: Expect assessors to spend 20–30 minutes longer on site gathering data, which Propertymark warns will push up fees.
- Documentation Is King: Without clear receipts, warranties, or manufacturer specs, recent upgrades may be ignored, forcing lower default ratings and potentially costly re-inspections.
- Rising EPC Costs: Typical EPCs currently cost £60–£120, depending on size and region. Industry insiders anticipate a 20–30% uplift post-June to reflect added assessor time and reporting complexity.
Action Plan: How to Get Ahead
Audit Existing Certificates
Review your current EPCs and identify properties due for renewal before 15 June. Pre-June assessments will still use the old RdSAP, potentially giving you more lenient ratings for a while longer.
Gather Your Paper Trail
Dig out invoices, manufacturer documentation, and installation certificates for any glazing, insulation, heating, or renewables work. Organise them digitally for instant access.
Plan Targeted Retrofits
Focus on low-cost, high-impact measures—like loft insulation or smart thermostats—to boost your rating and cash flow, especially with EPC C looming for new tenancies by 2030.
Budget for Higher Fees
Factor in potential EPC fees of £75–£150+ post-June, depending on property complexity and local assessor availability.
Looking Ahead: Why EPC Costs May Rise Further
As the UK pushes towards net-zero by 2050 and minimum EPC C ratings by 2030, EPC assessments will only grow more sophisticated. Future updates could:
- Shorten EPC validity (e.g., from 10 to 5 years), requiring more frequent surveys.
- Tighten fabric-first standards, mandating detailed moisture, thermal-bridge, or air-tightness tests.
- Incorporate real-time performance data via smart meters or IoT sensors, driving deeper data-collection and analysis.
- Expand to new technologies, such as advanced heat networks, electric vehicle charging integration, or on-site renewables, demanding assessor upskilling.
All of these factors - plus general inflation, software licensing for new RdSAP tools, and the limited pool of accredited assessors - point to rising EPC costs for years to come. Landlords who start building their evidence base now, and who budget for incremental survey fees, will be best placed to navigate this critical shift in UK rental regulation.
