EPC Changes June 2025: What You Need to Know
As of 15 June 2025, domestic Energy Performance Certificate (EPC) assessments in England, Wales, Scotland, and Northern Ireland will undergo a major transformation with the rollout of RdSAP 10 software. Spearheaded by the Department for Energy Security and Net Zero (DESNZ), this update aims to enhance accuracy, reflect modern building practices, and drive the UK toward its net-zero targets. For Domestic Energy Assessors (DEAs), the changes mean updated data-collection protocols, refined calculation methodologies, and new features for renewable technologies—and they’ll also lead to longer on-site visits and, consequently, higher EPC fees. In this article, we’ll explore what’s new in RdSAP 10, how it affects your EPC ratings, and why you should expect price increases for EPCs and energy performance assessments, particularly in light of the EPC Changes June 2025. (Energy Trust, Bluewire Hub Ltd)
1. Why RdSAP 10 Matters
The Reduced Data Standard Assessment Procedure (RdSAP) underpins EPCs for existing dwellings, providing the basis for energy-efficiency ratings that influence property valuations, rental regulations, and government incentives. The version in use since 2019 (RdSAP 9.94) has been due for a comprehensive overhaul to align with the UK’s evolving building stock and environmental goals. RdSAP 10 represents this first major leap forward, incorporating lessons from the Climate Change Committee’s net-zero roadmap and Government consultations on the Home Energy Model. DEAs will see more precise assessments of heat loss, renewable technologies, and carbon emissions—critical metrics as EPCs become increasingly central to policy instruments such as the Minimum Energy Efficiency Standards (MEES) and forthcoming mortgage-linked incentives. (GOV.UK, Elmhurst Energy)
2. Release Timeline and Preparation
- Specification Published: September 2023 (BRE)
- Training & CPD Rollout: From May 2025, all Accredited Bodies will integrate RdSAP 10 modules into their CPD sessions, ensuring assessors are up to speed on new protocols (Assessor Hub, Elmhurst Energy).
- Official Go-Live: 15 June 2025, when all accredited EPC software must migrate to RdSAP 10 (Energy Trust, Bluewire Hub Ltd).
Accreditation schemes (e.g., Elmhurst, Stroma, ECMK) are hosting webinars and issuing guidance documents. DEAs should begin reviewing the RdSAP 10 specification now, undertake relevant training, and upgrade data-capture equipment (e.g., tape measures, thermal imaging devices) in anticipation of increased measurement requirements. (Assessor Hub, EPC Training)
3. Key Changes in Data Collection
3.1 Comprehensive Window Measurements
Under RdSAP 10, every window in the dwelling must be measured and logged in full. This replaces the previous “typical window area” assumption and improves the precision of heat loss calculations. Expect site-time increases of 20–30 minutes per property due to:
- Manual measurement of frame dimensions (height, width) for each window (EPC Training, Energy Trust).
- Detailed recording of glazing types (single, double, triple), frame materials (uPVC, timber, aluminium), and presence of thermal breaks (EPC Training, Elmhurst Energy).
3.2 Enhanced Insulation Profiling
Insulation inputs now support finer gradations:
| Element | New Data Points |
|---|---|
| Walls | Thickness, material type, retrofit vs. integral |
| Roof | Depth, continuous vs. partial coverage |
| Floors | Board vs. cavity, layer composition |
| These refinements require DEAs to inspect cavities more closely and, where necessary, seek photographic evidence or homeowner documentation. (EPC Training, Energy Trust) |
3.3 Room-In-Roof Differentiation
Two separate “Room in Roof” types must now be identified: simplified or detailed. Detailed entries necessitate measurements of gable walls, common partitions, and roof slopes. This granularity aims to capture the thermal performance of loft conversions and attic bedrooms more accurately. (Elmhurst Energy, Assessor Hub)
3.4 Air-Tightness and Ventilation Options
RdSAP 10 introduces a broader array of ventilation types—mechanical extract, MVHR, trickle vents, and air-tightness test results where available. Where testers can supply an air-permeability test report, DEAs can input actual leakage figures, significantly improving the EPC’s reliability. (buildcomply.co.uk, Elmhurst Energy)
4. Methodology and Calculation Enhancements
4.1 Updated Thermal Properties
Thermal conductivity (U-values) for walls, roofs, and floors have been recalibrated to reflect modern insulation materials. This brings the RdSAP model in line with current British Standards and tested material performance, reducing discrepancies between predicted and actual energy use. (EPC Training, Elmhurst Energy)
4.2 Renewable Technology Integration
RdSAP 10 formally recognizes small-scale renewables, including:
- Battery Storage: Allows assessors to model on-site solar storage, adjusting import/export dynamics.
- PV Diverters: Models the benefit of diverting excess PV generation to electric hot water systems.
- Other Micro-Generation: Small hydro and combined heat-and-power (CHP) units can now be entered.
This leads to more accurate estimated energy savings and carbon scores, crucial for homeowners investing in renewables. (Elmhurst Energy, AES Sustainability Consultants)
4.3 Carbon Emissions Focus
With stricter carbon targets, RdSAP 10 calculates “CO₂ per m² per year” rather than just site energy use. This shift means properties with low-carbon heating (e.g., heat pumps) may see a proportionally greater uplift in their environmental rating, even if kWh consumption remains similar. (Elmhurst Energy, AES Sustainability Consultants)
5. Impact on EPC Ratings
By improving data fidelity and expanding technology inputs, RdSAP 10 is expected to produce:
- Higher accuracy: Reduced margin of error between modelled and actual bills.
- Potential rating shifts: Well-insulated homes with renewables may gain up to 5 rating points, while poorly insulated properties without ventilation control could lose points.
- Carbon score differentiation: Homes with low-carbon heat sources will perform better on the Environmental Impact scale than on Energy Efficiency alone.
DEAs should prepare clients for possible rating changes when RdSAP 10 assessments replace older EPCs—even without physical upgrades, ratings may change simply due to new calculation rules. (Energy Trust, Elmhurst Energy)
6. Increased Assessment Time and Cost Implications
The richer dataset and longer on-site processes mean that typical assessment times will rise by an estimated 25–40%. With average RdSAP 9.94 visits taking 45–60 minutes, assessors should budget up to 90 minutes under RdSAP 10. Consequences include:
- Reduced daily throughput: From 8–10 to 5–6 surveys per day.
- Higher operational costs: Increased travel time, data-entry labour, and training expenses.
- Fee adjustments: Most DEAs and accreditation bodies are reviewing pricing. Typical EPC fees may rise by 15–30% to cover the extra time and QA requirements.
Homeowners and landlords should expect higher quotes for EPCs and energy performance assessments post-June 2025. DEAs are advised to update fee schedules in advance and communicate the reasons—namely, enhanced accuracy and regulatory compliance. (EPC Training, Assessor Hub)
7. Preparing for RdSAP 10: Practical Steps for DEAs
- Attend Accredited Training: Secure CPD slots on RdSAP 10 modules immediately.
- Upgrade Equipment: Invest in precise tape measures, laser distance meters, and thermal imaging cameras.
- Revise Data Templates: Customize your data-capture forms to include new fields (windows, ventilation, renewables).
- Software Testing: Participate in pilot tests with your software provider to ensure a seamless June switchover.
- Client Communication: Draft new service proposals explaining the benefits of RdSAP 10 accuracy and the rationale for fee increases.
- Join Industry Forums: Engage in BRE and accreditation scheme webinars to stay updated on FAQs and errata. (Assessor Hub, AES Sustainability Consultants)
8. Frequently Asked Questions (FAQs)
Q1: Will my existing EPC remain valid after June 2025?
Yes—existing certificates remain valid for 10 years, but for new listings and government schemes, an RdSAP 10 EPC will be required for assessments carried out after 15 June 2025 (Bluewire Hub Ltd, GOV.UK).
Q2: How much more will EPCs cost?
While exact figures vary by region, most assessors anticipate a 15–30% fee increase to reflect longer on-site times and data processing (EPC Training, Assessor Hub).
Q3: Are there any exemptions?
Exemptions remain the same (listed buildings, temporary structures, houses of worship), but DEAs should confirm with their accreditation scheme whether certain data-collection steps can be waived when valid building records exist (GOV.UK, Elmhurst Energy).
10. Finally
The June 2025 rollout of RdSAP 10 represents a watershed moment for EPC professionals and homeowners alike. By demanding finer data-capture, integrating renewables, and re-focusing on carbon metrics, the new methodology promises more accurate, actionable certificates—albeit at the price of longer visits and higher fees. DEAs who prepare now—through training, equipment upgrades, and software testing—will gain a competitive edge, offering clients the most reliable energy-efficiency evaluations on the market. And by adopting SEO best practices, you’ll ensure that property owners and landlords find your updated services precisely when they need them most.
Embrace the change and position yourself as an RdSAP 10 expert—your clients, and your bottom line, will thank you.