The HEM-line blog

Created by Jon Ponting

The Home Energy Model (HEM) is a new way of forecasting the energy performance of residential buildings in the United Kingdom. In the coming years, HEM will replace the Standard Assessment Procedure (SAP) for generating Energy Performance Certificates (EPC) and checking compliance with Part L / Section 6 of Building Regulations.

HEM is currently in development. When it is approved for use, this blog will include tutorials and advice for how to use the new calculation tool.

While we're waiting, you can browse through this archive of my LinkedIn articles, covering changes to Building Regulations, Energy Performance Certification, national planning policy, and everything in between.

Elmhurst Cardiff Conference 2026

Plenty of thoughts still to digest after last week's Elmhurst Wales Conference in Cardiff. Great speakers, great venue, and very well organised. Top marks!

Part L

Jon Ponting

Oct 41 min read

A Domestic Energy Assessor looking worriedly at a neverending terrace of houses that need to have energy ratings calculated.

The roll-out of EPC Reform in Scotland

The Scottish Government has released more info about new-style EPCs, including a new go-live date. Unsurprisingly, they've delayed the launch until 2028. Soon, Scottish EPCs will start displaying three A-G ratings instead of one. Domestic properties will be ranked using heat retention (fabric performance), heating system efficiency and energy costs.

EPC

Jon Ponting

Sep 62 min read

EPC Reform: Non-Domestic edition

With all the recent talk about EPC Reform and new targets for residential buildings, you’d be forgiven for thinking, once again, that non-domestic buildings had been forgotten about. But that’s not the case. We have new commercial EPC targets on the way in both England and Wales.

EPC

Jon Ponting

Jul 52 min read

AI image of a terrace row of six houses. Solar panels and air source heat pumps are fitted to all dwellings.

FHS Launch - Impact on EPCs

With the Future Homes Standard set to go live across England next March, housebuilders will need to design in PV panels and install heat pumps to the vast majority of new buildings. That’s going to have a positive impact on Energy Performance Certificates... for now.

Part L

Jon Ponting

Apr 82 min read

For domestic properties, the single A-G rating will be replaced with three primary ratings, focusing on fabric performance, heating efficiency and 'Smart readiness'

EPC Reform postponed until 2027

Last week, the UK Government (representing England and Wales), and the Scottish Government both released statements saying EPCs will remain unchanged until late 2027. To recap, the way Energy Performance Certificates look, how results are graded, and the way they are calculated, are all changing. When it happens, it will be the biggest refresh to EPCs since their creation in 2008.

EPC

Jon Ponting

Mar 232 min read

A cartoon of Scottish tenement buildings, all with solar panels

Scotland Heat In Buildings Bill

Property owners in Scotland need to start planning for how to renovate homes they both rent out, AND live in. Proposals and timeframes for MEES differ from England and Wales, but the key objectives remain the same – to reduce energy use and carbon emissions generated by our homes.

Old buildings

Jon Ponting

Feb 232 min read

Social landlords should check the property's EPC. If the certificate is valid after April 2030 and achieves an A, B or C rating, no further action is required. Poor performing properties will need to be renovated to meet the new Standard.

New EPC Targets for Social Housing

The new Minimum Energy Efficiency Standards (MEES) for social housing in England will go live from April 2030. Landlords must ensure all homes comply by this deadline. If a property scores A-C using a current EPC, that's OK. If a property scores A-C under the fabric metric of the new EPC (available from the end of 2026), that's OK. For properties with a D, E, F or G rating, the landlord will need to make improvements to the energy performance.

Old buildings

Jon Ponting

Feb 42 min read

Private rental landlords should check the property's EPC. If the certificate is valid after October 2030 and achieves an A, B or C rating, no further action is required. Poor performing properties will need to be renovated to meet the new Standard.

2030 Changes to Minimum Energy Efficiency Standards

The new Minimum Energy Efficiency Standards (MEES) go live from October 2030. Landlords must ensure all rentals comply by this deadline. If a property scores A-C using a current EPC, that's OK. If a property scores A-C under the fabric metric of the new EPC (available from the end of 2026), that's OK. For properties with a D, E, F or G rating, the landlord must spend up to £10,000 making fabric and service improvements outlined in the EPC recommendations.

Old buildings

Jon Ponting

Jan 302 min read

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

The UK Government has set out plans to replace rdSAP10 assessments with the Home Energy Model. Domestic Energy Assessors (DEA) are still getting to grips with rdSAP10 (which was only implemented back in the summer) following years of delays. This consultation also considers how the new EPC metrics will be defined. You’ve got until March 18th, 2026 to have your say.

EPC

Jon Ponting

Jan 282 min read

EPC Reform: England and Wales

EPC certificates in England and Wales will be changing from October 2026. There will still be an A-G rating. But the single rating is being replaced with a dashboard of information, primarily focusing on fabric performance.

EPC

Jon Ponting

Jan 263 min read

For domestic properties, the single A-G rating will be replaced with three ratings, focusing on fabric performance, running costs, and the carbon intensity of the heating system.

Scotland EPC Reform Confirmed - What will new EPCs look like?

EPC certificates in Scotland will be changing from October 2026. There will still be an A-G rating. But to spice things up, we’ll get three of them, each considering different factors. The main metric will be a measurement of Fabric Performance. The better your house is at keeping the heat in, the better rating it will achieve. The Heat Retention Rating (HRR) is expected to award A ratings to the most insulated homes in Scotland (<30 kWh/m2 of heat loss), and B ratings <90.

EPC

Jon Ponting

Oct 27, 20252 min read

Scotland EPC Reform Confirmed - What & When

The Scottish Government has published what EPC Reform is going to look like. SAP assessors are advised to strap in… it could be a bumpy ride! Every EPC in Scotland will need to be redone, using a more complicated assessment tool that isn’t ready yet, with a nation of re-trained SAP assessors attending training courses that haven’t been written yet, signing up to 'new enhanced accreditation scheme requirements' that don’t exist yet.

EPC

Jon Ponting

Oct 19, 20252 min read

A typical Energy Performance Certificate for a dwelling in England

EPC accuracy in the spotlight (again)

It was good to see Elmhurst's Stuart Fairlie in this article, raising the issue of outdated methodology that currently drives our EPC ratings. It's after a chap installed a heat pump and PV in his house, and was given a worse Energy Performance Certificate for his troubles.

EPC

Jon Ponting

Sep 21, 20251 min read

Cartoon of window installers replacing the glazing in a castle with modern units to improve energy efficiency

Proposal for new look EPCs in Scotland

This consultation gives details for what the new EPC metrics may prioritise when assessors switch to the Home Energy Model. Fabric performance is likely to become the primary metric. It's highly possible that the whole of the UK will adopt a similar strategy in the coming years.

EPC

Jon Ponting

Jul 13, 20252 min read

A silhouette of a terrace of houses at sunset

EPC reform needed to help UK's retrofit market

House of Commons committee gives blunt but honest review of the current EPC process, and calls for reform to improve the accuracy of the information on the energy certificates.

Old buildings

Jon Ponting

Jun 1, 20252 min read