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A new name for a new methodology: what is the Home Energy Model?


In December 2023, the UK Government released consultations on the Home Energy Model; Home Energy Model: Replacement for the Standard Assessment Procedure (SAP) and the Home Energy Model: Future Homes Standard assessment.

These consultations present the government’s new calculation methodology, replacing the Standard Assessment Procedure (SAP) and used to assess whether new dwellings demonstrate compliance with the Future Homes Standard.

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What is the Home Energy Model?

The Home Energy Model is a government calculation methodology designed to assess the energy performance of homes across the United Kingdom and is set to replace the current methodology used by the government; the Standard Assessment Procedure (SAP).

Like SAP, the Home Energy Model will underpin a large number of government policies, making it of critical importance to the delivery of the government’s housing and climate policies.

The Home Energy Model is still under development at this stage. However, it’s first version is planned for implementation alongside the Future Homes Standard in 2025. Following this, it will then be expanded to include the production of Energy Performance Certificates (EPCs).

The deadline for the related consultations has now been extended to Wednesday 27th March 2024, due to an issue with the consultation version of the Home Energy Model.


What is SAP?

The Standard Assessment Procedure (SAP) is the methodology used by the UK government to estimate the energy performance of homes. The methodology has 2 main uses:

  • to demonstrate compliance of new homes with Part L of the Building Regulations.
  • to generate Energy Performance Certificates (EPCs) for all homes.

SAP plays a key role in developing, implementing and monitoring government policies and is used across the whole building industry.

SAP was initially developed by the Building Research Establishment (BRE) and was first cited as the means of assessing the energy performance of dwellings in the 1994 Building Regulations. Since then, SAP has gone through various iterations, with the current version, SAP 10.2, released in June 2022.

More robust, accurate and fit-for-purpose? 

This Home Energy Model project has big implications for the energy assessment industry, with the key aim of the project to modernise the relevant methodology in order to mirror the prevailing political and technological conditions in the UK. As the consultation states, it is ‘a new name for a new methodology’. The project will create a more robust, accurate and fit-for-purpose methodology that will support the UKs drive toward net-zero.

In contrast, the current SAP methodology can be seen as simple in comparison to today’s industry standards. This is because it was initially designed for an on-site assessor using basic tools such as a pen and paper, and, although it has gone through various updates, its core structure remains the same.

This project allows the government to create an up-to-date structure that better reflects the UK’s current political and technological landscape and facilitates the use of different sets of assumptions for different policy requirements. As the consultation notes, ‘it is imperative that the methodology is transparent, directly supports industry, policy, and research, and recognises buildings that are “net zero ready”’.

An updated methodology and ecosystem:

The Home Energy Model project provides the government with the opportunity to start from a clean slate and rethink the structure of SAP to ensure that its different use cases are clearly presented and separated. This is to be achieved through the complete overhaul of the methodology, with changes including:

  • Increasing the time resolution,
  • Building strong foundations on international standards,
  • A modular architecture,
  • Modelling energy flexibility and smart technologies,

as well as updates to the related ecosystem, including,

  • An open-source methodology,
  • Changes to the delivery model and provision of software,
  • A revised database of product characteristics,
  • Recognising new technologies,
  • Using “wrappers” to distinguish different use cases.

The government notes that this new structure will lead to several benefits, including increased flexibility (with wrappers able to be updated independently of one another and the core model), greater clarity and accountability and the opportunity to use different standardised assumptions, rather than having to rely on something that already exists.

After the consultation period has ended, the government will be considering reforms to how the model will recognise new technologies and product-specific performance data, as well as how software is provided to energy assessors.


Elmhurst Response

The rationale behind the Home Energy Model is to fundamentally improve the calculation methodology used for energy performance assessments and the output of these; to ensure that they are more robust and fit for the future. Elmhurst’s believes this to be a positive step.

Rather than a direct replacement of SAP, this change should be viewed as an enhancement to support the transition to net zero. Elmhurst has every confidence that the importance of energy professionals, assessments and Energy Performance Certificates looks to only be increasing as we move towards 2025.

In order to keep members up-to-date, Elmhurst will be releasing a series of articles over the coming months covering the Home Energy Model in more depth, including it’s potential impact on Energy Performance Certificates, the timelines for implementation and more. Keep an eye out for our next article in the coming weeks.

For more information and to view the government consultations, please click the following links:

Home Energy Model: replacement for the Standard Assessment Procedure (SAP): https://www.gov.uk/government/consultations/home-energy-model-replacement-for-the-standard-assessment-procedure-sap

Home Energy Model: Future Homes Standard assessment: https://www.gov.uk/government/consultations/home-energy-model-future-homes-standard-assessment