Phasing inEnergy & Carbon
SAP 10.3 / HEM: Energy calculation methodologies
SAP 10.3 and the Home Energy Model
The approved calculation methods used to demonstrate Part L compliance: SAP 10.3 at the launch of the 2026 standards, with the Home Energy Model expected to run alongside it.
Also known as: SAP, SAP 10.3, HEM, Home Energy Model, SBEM, NCM
Key requirements
- SAP 10.3 is the approved methodology for the Future Homes Standard at launch.
- HEM is expected to become an approved methodology no earlier than three months after the March 2026 response.
- A dual-running period of at least 24 months is planned.
- Non-domestic compliance continues to use the National Calculation Methodology (SBEM), subject to review.
- Assessors should track which methodology applies to each project's transition date.
Performance at a glance
- Dwellings
- SAP 10.3 → HEM
- Dual running
- ≥24 months
- Non-domestic
- NCM / SBEM
Applies to
New dwellings and non-domestic buildings demonstrating Part L compliance in England.
Related records
Reviewed 25 October 2026. This summary is an editorial reference, not legal advice. Check the current official text and confirm the approach with building control before relying on it. Browse all 35 records.