Energy Performance Certificates (EPCs) in the UK are being fundamentally reformed. The familiar single A–G rating will be replaced by four separate metrics — Fabric Performance, Heating System, Smart Readiness, and Energy Cost — giving homeowners, buyers, and landlords a much clearer picture of how a property actually performs. The new EPCs will be calculated using the Home Energy Model (HEM) instead of SAP and RdSAP, with a target launch date of October 2026.
What Is Wrong with Current EPCs?
The current EPC system, introduced in 2007, has several widely acknowledged shortcomings:
- Single rating hides important detail — a property with excellent insulation but an old gas boiler gets the same overall score as one with poor insulation and a slightly newer boiler
- Based on energy cost, not efficiency — the A–G rating reflects fuel costs rather than actual energy performance, meaning cheap gas can mask poor fabric
- Outdated calculation — RdSAP uses monthly averages and cannot accurately model heat pumps, solar PV, or smart controls
- Inconsistent results — different software providers can produce different results for the same property
- Limited retrofit guidance — the current EPC recommendations are generic and often impractical
What Does the New EPC Look Like?
Under the new system, an EPC will display four separate metrics instead of a single rating. This allows homeowners and buyers to see exactly where a property excels and where it needs improvement:
| Metric | What It Tells You | Why It Matters |
|---|---|---|
| Fabric Performance (A–G) | How well the building's walls, roof, floor, and windows retain heat | Shows the quality of the building itself, independent of heating system |
| Heating System (A–G) | How efficient and low-carbon the heating system is | Fossil fuel heating cannot achieve C — drives the shift to heat pumps |
| Smart Readiness (A–G) | How well the home can interact with smart energy systems | Rewards battery storage, smart controls, and demand flexibility |
| Energy Cost (£) | Estimated annual energy running costs | Directly comparable between properties — what you'll actually pay |
For a detailed explanation of how each metric is calculated, see our New EPC Metrics Explained page.
How Will the New Assessment Work?
New-Build Homes
For new homes, the EPC will be generated from the same HEM assessment used to demonstrate compliance with the Future Homes Standard. The compliance assessment already calculates all the data needed for the four EPC metrics, so no separate assessment is required. The EPC is effectively a by-product of the compliance calculation.
Existing Homes
For existing homes, an energy assessor will visit the property and collect data using a modular input framework. This replaces RdSAP's rigid data collection model:
- Assessors record what they can directly observe — wall construction, window types, heating system, insulation where visible
- HEM applies calibrated defaults for elements that cannot be determined on site (for example, exact wall insulation thickness in a cavity wall)
- The same HEM engine runs the calculation via the ECaaS platform, ensuring consistency
- More detailed data (from building surveys or retrofit plans) can be fed in for a more accurate result
For more on the transition from RdSAP, see our RdSAP Transition page.
What This Means for Homeowners
If you own a home, here is what you need to know:
- Your existing EPC remains valid for 10 years from issue — you do not need to get a new one until you sell, let, or it expires
- The transition is gradual — from October 2026 to October 2029, new EPCs will show both the old A–G rating and the new four metrics
- Fossil fuel heating will score poorly on the Heating System metric, which may influence property valuations over time
- Good fabric will be properly credited — if you have invested in insulation, this will show clearly in the Fabric Performance metric
- Smart technology is rewarded — battery storage, smart heating controls, and EV charging capability all contribute to the Smart Readiness score
What This Means for Landlords
Landlords should pay particular attention to the EPC reform. The Minimum Energy Efficiency Standards (MEES) currently require rental properties to achieve at least an E rating. The government has consulted on raising this to C, and the new four-metric system may change how minimum standards are defined:
- Minimum standards may apply to individual metrics rather than a single overall rating
- Properties with gas boilers will be unable to achieve C on the Heating System metric, potentially requiring heating system upgrades
- The separate Fabric Performance metric provides a clearer basis for assessing improvement requirements
Frequently Asked Questions
When do EPCs change to the new format?
New HEM-based EPCs are targeted for launch from October 2026. The existing A–G rating continues alongside the new metrics until October 2029. After that, all new EPCs use the four-metric framework only. Existing EPCs remain valid for 10 years from issue.
Will the new EPCs affect property values?
The new metrics provide more detailed performance information, which may influence buyer and lender decisions. Properties with fossil fuel heating will score poorly on the Heating System metric (cannot achieve C or above), which could affect perceived value. However, properties with good fabric but old heating may benefit from the separate Fabric Performance metric, which was previously hidden in the single score.
Do I need to get a new EPC when the system changes?
No. Existing EPCs remain valid for 10 years. You only need a new one when selling or letting, or when your current EPC expires. During the transition (October 2026 to October 2029), new EPCs will show both the new four-metric framework and the existing Energy Efficiency Rating.
Why can't fossil fuel heating achieve a C rating?
The Heating System metric assesses both efficiency and carbon intensity. Fossil fuels produce significantly more carbon per unit of useful heat than heat pumps, even when the boiler is efficient. The banding thresholds are calibrated so that fossil fuel systems cannot achieve C or above, reflecting the government's net zero objectives.
What is the Smart Readiness metric?
Smart Readiness measures a home's capacity to interact with smart energy systems — smart controls, battery storage, EV charging, and demand-side response. A home with a heat pump, battery, and smart controls scores highly. This metric encourages homes to be “grid-ready”, able to shift demand in response to grid signals and benefit from time-of-use tariffs.