Energy Performance Certificates (EPCs) are an essential part of the UK property market. Whether you’re selling, renting, or improving a home, an EPC provides an official assessment of a property’s energy efficiency.
However, the UK government is currently developing a new system called the Home Energy Model (HEM) which is expected to significantly change how domestic EPCs are calculated in the future.
While EPCs themselves are unlikely to disappear, the methodology behind them is set to evolve. The introduction of the Home Energy Model could lead to more detailed assessments, new performance metrics, and potentially different property ratings.
In this article, we explore what the Home Energy Model is and how it may impact EPC assessments in the coming years.
What Is the Home Energy Model?
The Home Energy Model (HEM) is a new government-developed system designed to assess the energy performance of homes in England and Wales.
It is intended to replace the current Standard Assessment Procedure (SAP) and Reduced Data SAP (RdSAP) methodologies that are currently used to generate Energy Performance Certificates.
SAP has been the official method for calculating residential energy efficiency in the UK since the 1990s. However, as housing technology has evolved — particularly with the growth of renewable energy systems and heat pumps — the government believes a more advanced model is needed.
The Home Energy Model will provide a more detailed simulation of how homes use energy, allowing for a more accurate representation of building performance.
Ultimately, the HEM will become the calculation engine behind future EPCs and other building energy assessments.
Why the Government Is Reforming EPC Calculations
The current EPC system has been widely used for many years, but it has several limitations.
One of the most common criticisms is that EPC ratings are largely based on estimated energy costs rather than pure energy efficiency or carbon emissions.
This can sometimes create unexpected results. For example:
- Homes using electric heating or heat pumps may receive lower EPC scores because electricity costs more than gas.
- Properties with high levels of insulation but electric heating can sometimes score lower than less efficient gas-heated homes.
As the UK moves towards low-carbon heating and net-zero emissions, policymakers want EPCs to better reflect the true energy performance of buildings.
The Home Energy Model is intended to support this transition.
Key Changes the Home Energy Model Could Introduce
More Advanced Energy Modelling
One of the biggest technical changes is the way the new model calculates energy use.
The current SAP system uses monthly averages to estimate how a building performs. The Home Energy Model will simulate energy use at 30-minute intervals throughout the year.
This allows the model to better account for factors such as:
- Solar gains from sunlight
- Daily heating patterns
- Smart energy tariffs
- Heat pump performance
- Thermal storage in buildings
This higher level of detail should provide more realistic predictions of how a home performs in real life.
More Detailed Property Data
The Home Energy Model will also use a much larger database of building products and technologies.
This includes improvements to the government’s Product Characteristics Database (PCDB), which stores performance data for heating systems, insulation products and other building components.
By expanding this database, EPC calculations should better reflect the actual performance of modern building technologies rather than relying on simplified assumptions.
New EPC Metrics Instead of a Single Rating
Currently, EPCs present a single A–G rating based primarily on estimated energy costs.
Under proposed EPC reforms, future certificates could include multiple performance metrics rather than one overall score.
These may include:
- Energy Cost Rating – estimated energy bills
- Fabric Performance – how well the building retains heat
- Heating System Performance – efficiency and carbon impact of heating systems
- Smart Readiness – ability to work with smart grids and flexible tariffs
Providing several metrics could help homeowners better understand where improvements should be made and which upgrades will have the biggest impact.
How This Could Affect EPC Ratings
Because the calculation method will change, some homes may see different EPC ratings once the Home Energy Model is introduced.
For example:
- Homes with good insulation and fabric efficiency may perform better.
- Heat pumps and low-carbon heating systems may be assessed more fairly.
- Some homes may receive different improvement recommendations.
However, it is important to note that EPCs will still remain a legal requirement when selling or renting a property.
What This Means for Domestic Energy Assessors?
For Domestic Energy Assessors (DEAs), the Home Energy Model represents the biggest methodological change to EPCs in many years.
The transition will likely involve:
- New assessment software
- Updated training requirements
- Changes to how EPC reports are presented
- New data collection standards
However, early indications suggest that on-site surveys for existing properties will remain broadly similar, as the government still intends to use a reduced-data approach for existing dwellings.
When Will the Home Energy Model Be Introduced?
The Home Energy Model is still under development and subject to consultation. Current government plans suggest the new methodology could begin to appear in EPC reforms from around 2026 onwards.
Before implementation, there will likely be a period of:
- Industry consultation
- Software development
- Training for assessors
- Gradual introduction of the new EPC format
This will allow the property sector time to adapt to the new system.
The Future of EPCs in the UK
While the methodology behind EPCs may change, Energy Performance Certificates will remain an important part of the UK housing market.
In fact, the introduction of the Home Energy Model could make EPCs:
- More accurate
- More useful for retrofit planning
- Better aligned with the UK’s net-zero goals
For homeowners and landlords, this should provide clearer guidance on improving the energy efficiency of their properties.
Need an EPC for Your Property?
If you’re selling or renting a property, a valid Energy Performance Certificate (EPC) is a legal requirement.
EPC Bromley provides fast and reliable EPC assessments for homes, helping you meet legal requirements and understand your property’s energy efficiency.
👉 Contact us today to book your EPC assessment.