The Home Energy Model (HEM) is the new methodology that will replace the current EPC system from H2 2027. Instead of a single A-G rating, HEM introduces four separate metrics that provide a more detailed picture of a property's energy performance.
✅ Updated Timeline: The government confirmed in March 2026 that HEM will launch in the second half of 2027, running alongside the current system until 1 October 2029.
What the Home Energy Model Is
HEM is a new assessment methodology designed to replace SAP (Standard Assessment Procedure) and RdSAP (Reduced data SAP):
Key Differences from Current System
- Four metrics instead of one: More granular performance measurement
- Actual building performance: Better reflects real-world energy use
- Climate-specific calculations: Considers local weather patterns
- Smart technology integration: Recognizes modern home automation
- Future-proofed design: Adaptable to emerging technologies
Why HEM Was Developed
- Current system limitations: SAP developed in 1990s, outdated for modern homes
- Standardized assumptions: Current EPCs use generic occupancy patterns
- Missing technologies: SAP doesn't adequately assess heat pumps, smart controls
- Policy misalignment: Single rating inadequate for complex 2030 requirements
HEM Timeline: H2 2027 Launch and Transition
Confirmed Timeline
| Date | Event | Impact |
|---|---|---|
| H2 2027 | HEM launches alongside current EER system | Choice of methodology for new EPCs |
| H2 2027 - Sept 2029 | Dual system operation period | Both EER and HEM EPCs valid |
| 1 October 2029 | All new EPCs must use HEM methodology only | End of EER system for new assessments |
| 1 October 2030 | All rental properties must meet EPC C (or HEM equivalent) | Compliance deadline using either system |
What Happens to Existing EPCs
- Remain valid until expiry: All current EPCs keep their 10-year validity
- No forced renewal: You don't need a new EPC just because HEM launches
- Can still be used for compliance: EER-based EPCs accepted until individual expiry
- Landlord flexibility: Can choose either system during transition period
The Four New HEM Metrics Explained
1. Fabric Performance
What it measures: The thermal quality of the building envelope - walls, roof, floor, and windows.
Components Assessed
- Wall insulation: Cavity, solid wall, external wall insulation
- Roof insulation: Loft, room-in-roof, flat roof insulation
- Floor insulation: Ground floor and suspended floor insulation
- Windows and doors: Double/triple glazing, frame materials, air tightness
- Thermal bridging: Heat loss at junctions between building elements
Why Fabric Performance Matters
- Foundation of efficiency: Good fabric reduces heating demand
- Works with any heating system: Benefits gas, electric, or heat pump systems
- Long-term value: Fabric improvements last 50+ years
- Comfort improvement: Better insulation means more comfortable homes
2. Heating System
What it measures: The efficiency and type of heating system, including controls and distribution.
System Types and Ratings
- Heat pumps: Air source and ground source - typically highest ratings
- Modern gas boilers: Condensing boilers with smart controls
- Electric systems: Direct electric, storage heaters - varies by system
- Biomass and renewable: Wood pellet boilers, solar thermal
- District heating: Connection to external heat networks
Control Systems Impact
- Smart thermostats: Learning and programmable controls
- Zone controls: Room-by-room temperature management
- Weather compensation: System adjusts to outdoor conditions
- Time controls: Sophisticated scheduling capabilities
3. Smart Readiness
What it measures: The property's ability to adopt and benefit from smart technologies and demand-side response.
Smart Technology Assessment
- Smart meters: Gas and electricity smart meter installation
- Smart heating controls: Internet-connected thermostats and valves
- Home automation: Integrated smart home systems
- EV charging readiness: Electrical capacity for electric vehicle charging
- Energy storage potential: Ability to install battery systems
Grid Integration Capabilities
- Demand-side response: Ability to adjust energy use based on grid needs
- Time-of-use optimization: Shifting energy use to cheaper periods
- Export capabilities: Solar panel electricity export to grid
- Vehicle-to-grid readiness: Future EV battery sharing with grid
4. Energy Cost
What it measures: Estimated annual running costs for energy, more accurately reflecting actual usage patterns.
Improved Cost Modeling
- Realistic occupancy: Based on property size and type, not standardized assumptions
- Local climate data: Heating degree days specific to location
- Current tariff structures: Reflects modern energy pricing including time-of-use
- Technology interactions: How different systems work together
Cost Categories
- Space heating: Largest component for most UK homes
- Hot water: Domestic hot water heating costs
- Lighting and appliances: Electricity for lighting and fixed appliances
- Renewable generation: Credits for solar panel or other generation
Dual-Metric Compliance for Landlords
The most significant change for landlords is the introduction of dual-metric compliance:
How Dual-Metric Works
- Primary standard: Must meet fabric performance threshold
- Secondary standard: Must meet EITHER smart readiness OR heating system threshold
- Both required: Cannot achieve compliance with fabric performance alone
- Flexibility: Choose heating or smart route for secondary compliance
Compliance Pathways
- Pathway 1: Good fabric performance + efficient heating system
- Pathway 2: Good fabric performance + high smart readiness
- Both pathways acceptable: Landlords can choose most cost-effective route
Practical Implications
- Insulation still essential: Fabric performance is non-negotiable
- Heating vs smart choice: Heat pump vs smart technology investment decision
- Property-specific solutions: Different properties may suit different pathways
- Cost cap still applies: £10,000 limit applies regardless of compliance pathway
What This Means for Different Property Types
Modern Properties (Post-2000)
- Good fabric performance: Likely to meet fabric standards already
- Focus on heating and smart: May need smart controls or heating upgrades
- High smart readiness potential: Easier to retrofit smart technologies
Victorian and Edwardian Properties
- Fabric challenges: Solid walls, poor insulation, period features
- Major investment required: Fabric improvements expensive but essential
- Smart technology easier: May be easier route for secondary compliance
1960s-1990s Properties
- Mixed performance: Some insulation but often inadequate
- Cavity wall potential: Often easy to improve with cavity fill
- Heating system upgrades: May need boiler replacement
Will My Current EPC C Still Be Valid?
This is a critical question for landlords preparing for 2030:
Existing EPC C Properties
- Remain valid until expiry: Current C-rated EPCs still meet legal requirements
- May be reassessed differently: Same property might get different rating under HEM
- No automatic compliance: HEM may reveal different strengths/weaknesses
- Strategic consideration: Whether to get new HEM assessment before 2030
Properties Currently Rated D or E
- May benefit from HEM: New methodology might reveal better performance
- Smart technology boost: Smart readiness could improve overall compliance
- Modern heating systems: Heat pumps better recognized under HEM
HEM vs Current EPC: Side-by-Side Comparison
| Aspect | Current EPC (SAP/RdSAP) | New HEM System |
|---|---|---|
| Rating display | Single A-G band | Four separate metrics |
| Compliance (landlords) | Single threshold (EPC C) | Dual-metric: fabric + (heating OR smart) |
| Climate consideration | Regional averages | Local weather station data |
| Smart technology | Limited recognition | Dedicated smart readiness metric |
| Heat pump assessment | Often undervalued | Better recognition of performance |
| Occupancy assumptions | Standardized patterns | Property-specific modeling |
| Cost estimates | Basic calculation | Realistic usage patterns |
What Homeowners Need to Know
If You're Selling
- Current EPCs still valid: Can use existing EPC until it expires
- Consider HEM assessment: Might get better rating with new system
- Highlight improvements: Smart technology and modern heating better recognized
If You're Improving Your Home
- Fabric first principle remains: Insulation still most important
- Smart technology value: Smart thermostats and controls now contribute to rating
- Heat pump benefits: Better recognition may justify installation
When Will You Need to Consider HEM?
Immediate Considerations (2027-2029)
- New EPC needed: May choose HEM if it gives better rating
- Property improvements: Consider how changes will be assessed under both systems
- Investment decisions: Plan improvements that work well under HEM
Longer-term Planning (2029+)
- All new EPCs use HEM: No choice after October 2029
- Existing EPCs still valid: Until their individual expiry dates
- Market expectations: Buyers and tenants may prefer HEM assessments
Official Government Resources
- GOV.UK: HEM EPC Consultation — Official consultation documents
- GOV.UK: HEM Methodology — Technical details
- Home Energy Model Dedicated Site — Implementation timeline
- CIBSE — Chartered Institution of Building Services Engineers guidance
- The Independent Landlord: HEM Guide — Practical landlord guidance
EPC
About This Guide
This guide was researched and written by the EPC Certificate UK Editorial Team, specialists in UK energy performance regulations. All information is sourced from official government publications, regulatory announcements, and industry best practice guides.
Published: 14 April 2026Methodology: How we research