The New HEM EPC Methodology: What Changes for Landlords in 2029

What Is HEM?

The Home Energy Model (HEM) is the government's replacement for RDSAP — the methodology currently used to calculate domestic EPC ratings. It was originally scheduled for October 2026 but has been delayed to the second half of 2027 following industry feedback.

RDSAP has been around since 2005 and uses simplified assumptions about how buildings use energy. HEM is significantly more detailed, modelling things like occupancy patterns, half-hourly energy use, and smart heating controls.

Update (March 2026): The government confirmed the HEM launch has been pushed to late 2027. The MEES 2030 deadline remains unchanged — all rental properties must still reach Band C by October 2030.

What Changes for Landlords?

Under HEM, EPC ratings will work differently:

Dual metrics instead of a single band. HEM introduces a Fabric Performance Metric and either a Heating System Metric or a Smart Readiness Metric. Properties must satisfy the fabric standard plus one of the other two. This is a more complex system than the current single A–G band.

Some ratings may change. Properties that perform well under RDSAP might score differently under HEM, and vice versa. For example, HEM gives more credit to smart heating controls and thermal mass, but may be stricter on poorly insulated fabric.

New assessment process. HEM assessments will likely take longer and may cost more than current EPCs. Assessors will need new qualifications.

Why the Delay Actually Benefits Landlords

The HEM delay to late 2027 creates a wider window to act under the current, simpler RDSAP system. Properties that achieve EPC Band C under RDSAP are deemed compliant for the remaining life of that EPC — up to 10 years.

This means a property that gets an EPC C in 2026 or 2027 under the current system is compliant until 2036-2037, regardless of how it would score under HEM.

The industry has warned that HEM uncertainty is causing landlords to "sit on their hands." But waiting is risky — the 2030 deadline hasn't moved, and acting now under the known rules is safer than waiting for a system that doesn't exist yet.

What Should You Do?

Act now under the current RDSAP system. Get your improvements done and commission a new EPC while RDSAP is still available. This locks in your compliance for 10 years.

Focus on fabric first. Under HEM, fabric performance is a standalone requirement. Insulation (loft, walls, floor) and glazing upgrades will be essential regardless of the new methodology.

Don't wait for HEM details to be finalised. The improvements that work under RDSAP — insulation, efficient heating, controls — will still be valuable under HEM. There's no scenario where insulating your property becomes a bad investment.

Check Your Position

Use our tool to see where your property stands now and what it needs to reach Band C under the current system. The sooner you act, the longer your RDSAP-based compliance lasts.