EPC Reform: The End of rdSAP10 (Yes, already!)

[Update: The launch of HEM based EPCs has been delayed until late 2027]

In amongst the noise of the Warm Homes Plan release this week, the UK Government also set out plans to replace rdSAP10 assessments with the Home Energy Model.

Domestic Energy Assessors (DEA) - who complete EPC surveys on existing homes - are still getting to grips with rdSAP10 (which was only implemented back in the summer) following years of delays.

The consultation also considers how the new EPC metrics (see previous post) will be defined. You’ve got until March 18th to have your say: 

https://www.gov.uk/government/consultations/home-energy-model-energy-performance-certificates

The intention is to phase in new-style EPC surveys, using the Home Energy Model, from October 2026. rdSAP will be phased out over the next few years.

❓ Why change already:

Government is changing the design of EPCs. The new look will feature a dashboard of results with more accurate information that better reflects real-life energy use. SAP simply isn’t clever enough to deliver this.

The way HEM calculates energy performance is worlds apart from SAP, and is designed to be easily updated so new tech can be easily integrated.

One of the issues with rdSAPs accuracy is the amount of assumptions it makes, which are not editable by assessors.

Take wall U-Values for example. The assessor selects a wall type, adds an approximate age of the property, and rdSAP decides what the U-Value is.

HEM will unlock all of these assumed areas, so if evidence of a U-Value is available, such as the original Part L reports, they can be included in the assessment and improve the accuracy of the result.

And if this info isn't to hand, there'll still be assumptions available to use.

HEM will also includes things that are ignored by SAP. Thermal batteries and cookers will be in the first release, with EV Chargers likely to feature in a future update.

⏰ When will this happen?

The plan is to have approved HEM software available for DEAs from this October. It’s certainly ambitious, given that HEM methodology is still being written and there’s been no confirmation of accreditation requirements yet.

There won’t be an immediate switchover. We’ll have a stage where both rdSAP and HEM models will be acceptable for EPC generation. The new Minimum Energy Efficiency Standards (MEES) are going to steer us towards HEM by requiring all private rentals to have compliant new-style EPCs by 2030 (see next post).

There was talk of reducing the validity period of EPCs from 10 to 5 years, to match the plan in Scotland. But for England and Wales, for now at least, HEM based EPCs will continue to be valid for 10 years.

💰 Drawbacks

We know HEM is going to be a more complicated than SAP, so will this increase the time taken on assessments?

If adding extra data is optional in HEM, will assessors be willing to put their prices up to deliver more accurate results, or will they keep prices low and stick to assumptions?

The consultation asks these questions. Use the above link to have your say.