The Home Energy Model
A New Standard.
The Home Energy Model (HEM) is the UK government’s new calculation engine for assessing the energy performance of new homes. It replaces SAP, which has been in use for over 30 years. HEM is designed to support the Future Homes Standard, which aims to ensure that new homes produce low to zero operational carbon emissions from 2026.
Why Is SAP Being Replaced?
SAP has been used for many years, but it was designed for a time when homes relied on gas boilers and far simpler systems. As the industry moves toward low carbon heating and smarter, more efficient homes, SAP can’t provide the level of accuracy needed. The new Home Energy Model (HEM) gives a much clearer picture of how modern technologies perform, from heat pumps to solar panels and battery storage. It also offers more realistic insights into heating and cooling demands throughout the year.
Government guidance makes it clear that HEM is built to be flexible, transparent, and ready for future technologies, supporting the UK’s long term move toward net zero.
How can Home+ Energy Support You?
We provide clear, practical guidance at every stage from early feasibility to final compliance. Whether you’re building one home or a large development, we can help you meet the new standards without unnecessary cost or complexity.
Increased design coordination
Heat pumps, PV, and improved fabric standards will require earlier integration between architects, M&E designers, and energy assessors.
Higher build costs (initially)
Low‑carbon technologies and improved fabric performance may increase upfront costs, though operational savings for homeowners will be significant.
More predictable compliance
HEM’s accuracy reduces the risk of late‑stage design changes to meet Part L.
How Will This Impact Self‑Builders?
More planning at the design stage
Self‑builders will need to consider heat pump sizing, PV layout, and airtightness strategies earlier.
Greater emphasis on build quality
Airtightness testing, thermal bridging details, and ventilation commissioning will be more important than ever.
Lower running costs
Homes built to the Future Homes Standard will be significantly cheaper to heat and power.
How Will This Impact Architects?
Design flexibility
Architects will need to balance aesthetics with:
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PV roof area
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Heat pump placement
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Ventilation ducting
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Fabric performance targets
Earlier collaboration
Energy modelling will need to be integrated from RIBA Stage 2–3 rather than left until later.
More accurate performance predictions
HEM’s hourly modelling gives architects better insight into overheating risk, peak loads, and energy use.
2026 Part L / Future Homes Standard
Fast Turnaround
Get your report quickly so your project keeps moving.
Clear, Simple guidance
No confusing technical language, just what you need to stay compliant.
Competitive Pricing
High‑quality service without the inflated fees.
Expert Support
Need advice on meeting tighter targets? We’ll guide you through the best options.
Be ready for now and what’s next. Home+ Energy supports you through both current SAP compliance and the transition to HEM.