New EPC Rating System 2026: Four Metrics Replacing the A to G Scale
The new EPC rating system 2026 marks the biggest overhaul of property energy assessment in the UK since EPCs were introduced in 2007. The familiar A-to-G scale is being replaced by four separate metrics covering Fabric Performance, Heating System Efficiency, Smart Readiness, and Energy Cost, all underpinned by the new Home Energy Model (HEM) that replaces the ageing SAP methodology. With a parallel running period starting in H2 2027 and full transition by October 2029, this guide explains what is changing, why it matters, and what homeowners need to do.
What Is the New EPC Rating System in 2026?
The UK government is replacing the current A-to-G EPC scale with a new system that uses four separate metrics: energy efficiency, estimated energy costs, environmental impact and a comfort rating. Instead of a single letter grade, each property will receive scores across all four categories, giving buyers and tenants a more detailed picture of a home’s performance.
| New Metric | What It Measures | Why It Matters |
|---|---|---|
| Energy efficiency (kWh/m²) | How much energy the home uses per square metre | Shows actual energy demand regardless of fuel type |
| Estimated energy cost (£/year) | Predicted annual energy bill | Helps buyers and renters budget accurately |
| Environmental impact (kgCO₂/year) | Carbon emissions from heating and electricity | Reflects the home’s contribution to climate change |
| Comfort rating | Likelihood of overheating, cold spots and draughts | Indicates real-world livability |
The new system is expected to be phased in during 2026–2027. Existing EPCs will remain valid until they expire (10 years from issue). The change means homes heated by low-carbon sources like heat pumps will score significantly better on environmental impact, while the comfort metric will highlight problems such as poor ventilation or single glazing that the current system largely ignores.
Why the EPC System Is Changing
The current EPC system, based on the Standard Assessment Procedure (SAP), has been criticised for years. The main problems include the following.
- Outdated methodology: SAP was designed in the 1990s and does not adequately account for modern technologies like heat pumps, battery storage, and smart heating controls
- Cost-focused rather than carbon-focused: The current A-to-G rating is based primarily on energy costs rather than actual energy consumption or carbon emissions
- Volatile ratings: Because the rating is tied to energy costs, it fluctuates with tariff changes even when the physical property has not changed
- Oversimplified: A single letter grade cannot capture the complexity of a home’s energy performance across multiple dimensions
- Gaming potential: Some measures that improve the EPC score do not deliver proportional real-world savings
The government commissioned the Home Energy Model to address these shortcomings and provide a more accurate, comprehensive, and future-proof assessment framework.
The Home Energy Model: Replacing SAP
The Home Energy Model (HEM) is the new calculation engine that will underpin all EPC assessments. It represents a fundamental upgrade to how homes are evaluated.
Key Improvements Over SAP
- Physics-based modelling: HEM uses more detailed thermodynamic calculations that better reflect real-world energy flows in buildings
- Half-hourly energy modelling: Instead of annual averages, HEM calculates energy demand in half-hourly intervals, capturing the impact of time-of-use tariffs and solar generation patterns
- Better heat pump modelling: HEM accurately models heat pump performance at different outdoor temperatures and flow temperatures, giving more realistic efficiency figures
- Smart technology recognition: Smart thermostats, battery storage, demand-side response, and other intelligent systems are properly accounted for
- Occupancy patterns: HEM considers how different occupancy profiles affect energy consumption, rather than assuming a one-size-fits-all pattern
The Four New EPC Metrics Explained
Instead of a single A-to-G letter, the new EPC will display four separate metrics, each providing different information about the property’s energy characteristics.
1. Fabric Performance
This metric measures how well the building envelope retains heat. It considers insulation levels in walls, roof, and floor, window performance, airtightness, and thermal bridging. A high Fabric Performance score means the home loses less heat through its structure, regardless of what heating system is installed.
This metric is particularly important because fabric improvements are permanent. Unlike heating systems that need replacing every 15-20 years, good insulation lasts the lifetime of the building.
2. Heating System Efficiency
This metric rates the efficiency of the primary heating system. It considers the technology type (gas boiler, heat pump, electric heating), the specific efficiency rating, heating controls, and how well the system is matched to the property’s heat demand.
Heat pumps will score significantly higher than gas boilers under this metric because they deliver 2.5-4 units of heat for every unit of electricity consumed, compared to a maximum of 0.92 for even the best condensing gas boilers.
3. Smart Readiness
A completely new addition, this metric assesses the property’s ability to interact with the smart energy grid. It considers the following.
- Smart meter installation
- Smart thermostat and heating controls
- Battery storage capability
- Electric vehicle charging readiness
- Solar panel integration with smart export
- Demand-side response capability
As the electricity grid becomes more dependent on renewable generation, homes that can shift energy consumption to match supply will benefit from lower costs and reduced strain on the network. The Smart Readiness metric rewards homes that are prepared for this future.
4. Energy Cost
This metric provides an estimated annual energy cost based on standardised occupancy assumptions and current energy prices. It is the most direct successor to the current A-to-G rating, but with improved accuracy thanks to the Home Energy Model’s better calculations.
Unlike the current system where the cost metric effectively determines the entire rating, under the new system it is just one of four metrics, preventing it from overshadowing the other important performance dimensions.
Transition Timeline: When the New EPC System Takes Effect
| Period | What Happens |
|---|---|
| 2026 | Home Energy Model finalised; assessor training begins |
| H2 2027 | Parallel running starts: EPCs can be issued under either SAP or HEM |
| 2027-2029 | Both systems run simultaneously; new format EPCs become increasingly common |
| October 2029 | Full transition: all new EPCs must use the Home Energy Model and four-metric format |
| Post-2029 | Existing SAP-based EPCs remain valid until their 10-year expiry date |
During the parallel running period, homeowners selling or letting a property can choose either the old or new format. However, the new format is expected to become the standard quickly as assessors are retrained and the industry adapts.
What the New EPC System Means for Homeowners
The new system will affect homeowners in several practical ways.
Property Values
Properties with strong scores across all four metrics will command premium prices. A home with excellent fabric performance, a heat pump, solar panels with battery storage, and smart controls will be the gold standard under the new system.
Improvement Priorities
Under the current A-to-G system, homeowners often focus on whichever measure delivers the most EPC points for the lowest cost. The four-metric system encourages a more balanced approach, investing in fabric, heating, smart technology, and cost reduction in proportion.
MEES Compliance
The MEES 2030 EPC C requirement for rental properties will need to be translated into the new four-metric system. The government has not yet confirmed exactly how MEES thresholds will map to the new metrics, but it is expected that minimum standards will be set for each metric individually.
Mortgage Lending
Lenders are increasingly factoring energy efficiency into mortgage decisions. The four-metric system gives lenders more granular data to assess a property’s energy costs and future improvement potential, which may influence lending criteria and green mortgage products.
If you want to future-proof your property for the new EPC system, get a free quote to explore which improvements will have the greatest impact across all four metrics.
How to Prepare Your Home
While the new system is still being finalised, the fundamentals of good energy performance remain the same. Here are the improvements that will score well under both the current and new systems.
- Insulate thoroughly: Loft, wall, and floor insulation will score highly on Fabric Performance
- Install a heat pump: Heat pumps will dominate the Heating System Efficiency metric
- Add solar and battery: Solar panels with battery storage will boost both Smart Readiness and Energy Cost metrics
- Upgrade controls: Smart thermostats and zoned heating controls improve both heating efficiency and smart readiness
- Improve airtightness: Draught-proofing and improved sealing boost Fabric Performance without major construction work
Frequently Asked Questions
Will my current EPC become invalid when the new system launches?
No. Existing EPCs issued under the SAP methodology remain valid for their full 10-year lifespan. You do not need to get a new EPC until your current one expires or you choose to commission one (for example, after making improvements). The transition only affects new EPCs issued from the changeover date.
Will the new EPC system make my property rating better or worse?
It depends on your property. Homes with good insulation and modern heating systems may score similarly or better. However, properties that scored well under SAP due to cheap gas heating may see their Heating System Efficiency metric drop because gas boilers perform poorly compared to heat pumps in the new calculation. The four-metric format means you cannot have a single “good” or “bad” rating; your property will have a more nuanced profile.
Do I need to wait for the new system before making improvements?
No. Improvements that benefit your home under the current system will also benefit you under the new system. Good insulation, efficient heating, and smart controls are valued by both methodologies. There is no advantage to waiting, and delaying improvements means paying higher energy bills in the meantime.
Will EPC assessors need new qualifications?
Yes. Assessors will need to complete training on the Home Energy Model and the four-metric assessment framework. This training programme is expected to begin in 2026, with assessors being certified to issue new-format EPCs before the parallel running period starts in H2 2027. During the transition, some assessors may only be qualified to issue old-format EPCs.
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