A major change is coming to how the energy efficiency of homes is measured in the UK – one that could affect every builder, developer, and renovator.
The government has announced the Home Energy Model, a new system set to replace the current Standard Assessment Procedure (SAP) and to calculate Energy Performance Certificates (EPCs).
For decades, SAP has been used to estimate a home’s energy use, but it relies on simplified assumptions and averages.
The Home Energy Model will use a different methodology to calculate energy use, taking into account the building, its systems, and how it is used, which we will explore to give you all the information you need once it is finally introduced.
Why the Home Energy Model is being introduced?
SAP uses simplified assumptions and monthly averages to estimate energy use. This approach does not fully reflect how modern homes operate, particularly those with heat pumps, solar panels, batteries, or other energy technologies.
The Home Energy Model addresses these limitations by simulating energy use over time, considering how homes are built and how they are occupied.
David Hilton, a renewable energy expert, commented on this transition: “Any new product takes time to transition in and there will need to be a lot of training, re-education and debugging of the system before it can finally settle. This transition is the key.”
For builders and renovators, this means energy assessments will provide a clearer view of a home’s performance, supporting design decisions, retrofits, and compliance with energy regulations.
With more than 35 years of expertise, David is a seasoned renewables and ventilation installer, recognised for his longstanding contributions to Homebuilding and Renovating magazine. Holding membership in the Gas Safe Register and armed with a Masters degree in Sustainable Architecture, David stands as an authoritative figure in sustainable building and energy efficiency. His extensive knowledge spans building fabrics, heat recovery ventilation, renewables, and conventional heating systems. Additionally, he serves as a distinguished speaker at the Homebuilding & Renovating Show.
How will the Home Energy Model work?
The Home Energy Model will estimate how much energy a home uses over the course of a year, producing a detailed simulation of heating, hot water, and electricity use.
It will take into account:
- The building itself – walls, floors, roof, windows, and insulation
- Heating and cooling systems – including boilers, heat pumps, and ventilation systems
- Renewable energy and storage – such as solar panels or batteries
- How the home is used – occupancy patterns and appliance use
From this information, the model produces results that show:
- Total energy use for heating, hot water, and electricity
- Energy use patterns throughout the day and across the seasons
- Energy performance metrics for EPCs, including running costs and carbon emissions
David Hilton also highlighted the challenge of introducing a new system to the industry: “The Home Energy Model looks to be a welcome improvement on SAP but until we actually have the final product and can see how it works and how it will be rolled out into industry it is very difficult to know what it will mean for the industry… I also wonder how keen the industry is for yet another change that will inevitably cost time and money in an already difficult market.”
The Home Energy Model turns information about a home and its use into a simulation of energy performance, which will be applied to building regulations and Energy Performance Certificates.
When will the Home Energy Model be introduced?
The Home Energy Model will be introduced when the Future Homes Standard comes into effect, setting updated energy efficiency requirements for newly built homes.
Initially, it will be used to assess compliance with the new standard. Over time, it will also be applied to Energy Performance Certificates for new and existing homes.
David Hilton noted the potential scepticism around the rollout: “There will inevitably be large amounts of scepticism due to history being plagued with expensive Government schemes that were destined to fail or were cancelled due to political U-turns. Something needs to be done, and hopefully this is it, but the reality of its efficacy will only really be evident in the fullness of time.”
During the rollout, there will be a transition period where both SAP and the Home Energy Model are available, giving builders, assessors, and software providers time to adapt.
What this means for builders and renovators
Once in use, the Home Energy Model will affect how energy performance is calculated and reported. Builders and renovators will need to:
- Consider how insulation, windows, heating systems, and renewable technologies affect energy ratings
- Understand that assessments and EPCs will be based on a simulation of how the home is used throughout the year, rather than simplified averages
- Plan for training and software updates, as the model is integrated into compliance checks and EPC production
David Hilton commented on the practical implications for industry professionals: “Any new product takes time to transition in and there will need to be a lot of training, reeducation and debugging of the system before it can finally settle. This transition is the key.”
The Home Energy Model will provide a consistent framework for assessing energy use and efficiency, helping industry professionals plan, build, and retrofit homes in line with updated regulations.
The Home Energy Model represents the next step in how the UK measures home energy performance. By simulating energy use in detail, it aims to provide more accurate assessments for building regulations and EPCs.
Builders and renovators will need to understand its implications, plan for the transition, and consider how building materials, systems, and occupancy affect energy performance.
While the system is not yet in use, preparing for the Home Energy Model now can help the industry adapt smoothly when it is introduced alongside the Future Homes Standard.
