What replaces SAP Appendix Q?

Innovative solutions will continue being created as we move to delivering net zero-ready homes which are affordable, responsive, and desirable. With it being proposed that the Standard Assessment Procedure (SAP) is replaced with the Home Energy Model (HEM), it is vital that these innovative solutions are easily incorporated into HEM to enable them to be deployed at scale.

Why is SAP Appendix Q being replaced?

Manufacturers can currently apply for new technologies to be recognised in SAP through a process called “Appendix Q”. Appendix Q enables performance information on new technologies to be used within SAP software.

There have been several criticisms of the current process, including:

  • Lack of transparency: Industry has reported a lack of clarity around the application process (including timeframes, level of evidence required etc.).
  • Financial and commercial risk weighted against the applicant: Industry has reported that the time and cost burden of the Appendix Q process presents a barrier to innovation.
  • Long timeframes: The Appendix Q process can take a long time and therefore prevents SAP from being more responsive to new innovative solutions.
  • Poorly integrated models: Separate “bolt-on” calculations are awkward for assessors and prevent new technologies from interacting properly with other Appendix Q technologies and some systems in the main SAP model.


What about the technologies currently in SAP Appendix Q?

Ahead of the Home Energy Model going ‘live’ in 2025 alongside the Future Homes Standard, Government aims to fully integrate all existing Appendix Q technologies into HEM and the product characteristics database.

To do this they will be engaging with manufacturers and industry sector representatives regarding their products’ implementation and encouraging manufacturers to engage with the open-source reference code and test how their technology could be modelled within the Home Energy Model for future consideration. The government and SAP contractor will provide more information on this process in due course.

What do we know about how new products will be recognised in HEM?

The government intends to reform the process for incorporating new technologies into HEM. It’s important that this new process strikes a balance between enabling novel, innovative technologies to be recognised in the Home Energy Model, whilst providing certainty of product performance.

It is hoped that HEM will enable new technologies to be recognised in the core engine on a more frequent basis, removing the need for a ‘bolt-on’ calculation. New technologies may also necessitate the creation of new HEM modules or modification of existing ones.

The approach for recognising new technologies in the Home Energy Model is still at an early development phase; however, Government intends to adopt the following principles:

  • Increased transparency: The process should be transparent, clearly defined, and easily understandable by industry.
  • Open research: A form of the assessment and/or evidence should be published to provide transparency and demonstrate a robust process, while protecting intellectual property and commercial competitiveness.
  • Integrity: The process should require robust evidence of the technology’s performance.
  • Continuous evaluation: The process should enable continuous evaluation of technology performance as new data is assessed.
  • Greater integration: The process should be integrated with other similar processes that recognise innovation (e.g. ECO, Great British Insulation Scheme, PAS 2035) to avoid applicants needing to repeat evidence gathering exercises and to meet all stakeholder requirements.

What next?

Government intends to work closely with manufacturers and industry representatives to develop the new process for adding innovative technologies to the future HEM. BEAMA will pass on any requests we receive to member, as we have done for previous PCDB/Appendix Q changes. If you have comments on the new process, this is covered in Question 11, 12 and 13 of The Home Energy Model: Making the Standard Assessment Procedure fit for a net zero future consultation:

11. What are your views on our assessment of issues with the way SAP currently recognises new technologies (currently the “Appendix Q process”)? Please provide your reasoning and any supporting evidence.

12. What are your views on the principles for how the Home Energy Model will recognise new technologies once it is in use? Please provide your reasoning and any supporting evidence.

13. What are your suggestions for how to integrate new innovative products into the Home Energy Model? Please provide your reasoning and any supporting evidence.

Please send your comments to your group lead or Amy Collins using our member feedback form.

To read more on the Future Homes Standards and the Home Energy Model, visit our central resource page.