October 2, 2025 was an important day for the UK energy sector as the Department for Energy Security and Net Zero (DESNZ) released its long-awaited consultation response on the Home Energy Model (HEM)—the methodology set to replace the decades-old Standard Assessment Procedure (SAP).
What You Need to Know
The core of the response confirms a shift to a more accurate, transparent, and digital calculation system for homes.
Joe Brennan, our Property Certification Manager, shares his immediate thoughts:
“The proposed Home Energy Model (HEM) will make schemes like ECO4, insulation upgrades, and EPCs far more accurate. The improved, half-hourly modelling gives a truer picture of a home’s energy use, helping customers choose measures more effectively.”
“A modernised Product Database (PCDB) will speed up the recognition of new technologies, ensuring your EPCs reflect the energy-efficient measures you actually install.”
“Overall, a new HEM will reduce performance gaps, improve compliance, and let customers make smarter decisions about improving their homes and lowering their bills.”
The HEM Transition: A Modern Digital Ecosystem
DESNZ has committed to building a new digital ecosystem for energy assessment, addressing many of the limitations of the old SAP system:
- Open-Source & Transparent: The HEM methodology will be published in an open-source environment to encourage peer review and greater transparency for the model’s core calculations.
- Centralised Cloud Service: The core HEM will be delivered via Energy Calculation as a Service (ECaaS), a centralised, cloud-based platform. This ensures consistency across all accreditation schemes, removes inconsistencies between software providers, and allows for immediate updates to the methodology.
- Half-Hourly Calculations: SAP worked on a monthly basis, but HEM will increase the time resolution to half-hourly timesteps. This allows to accurately model modern technologies like heat pumps, smart tariffs, and electric batteries.
The new model will be faster, more accurate, and better equipped to handle renewable technology.
We are now looking forward to the responses for the Future Homes Standard consultation, expected before the end of the year, which will outline how HEM will be applied to New Build Dwellings.
🔗 Read the full Government Response here:
https://assets.publishing.service.gov.uk/media/68dd03238c1db6022d0c9f82/home-energy-model-government-response.pdf
