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The HEM-line blog
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.
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New SAP Feature: Electric Showers and WWHRS
A new feature has been unlocked in SAP!
We can now attach Waste Water Heat Recovery systems to electric showers.
The shower has to be an approved Modulating Instantaneous Electric Shower.
Jon Ponting
Oct 112 min read
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!
Jon Ponting
Oct 41 min read
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.
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.
Jon Ponting
Jul 52 min read
New Part L for Wales (Targets and Notional)
This revised Approved Document Part L will apply to any building work where the relevant building inspector accepts applications from 4th March 2027.
Any unstarted buildings on existing sites after 4th March 2028 will need to meet the new regs, regardless of when the site was submitted.
As with the current Part L, most of the English (UK) and Welsh versions are identical, but there are a few curveballs developers need to be aware of.
Jon Ponting
May 102 min read
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.
Jon Ponting
Apr 82 min read
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.
Jon Ponting
Mar 232 min read
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.
Jon Ponting
Feb 232 min read
A New Decent Homes Standard
The Decent Homes Standard hasn’t been updated for 20 years.. no wonder its mere existence is news to many people! An overhaul is on the way.
DHS sets ‘baseline expectations of housing quality in the social rented sector’.
That definition is changing... From 2035, the Decent Homes Standard will also apply to rentals in the private sector.
Jon Ponting
Feb 92 min read
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.
Jon Ponting
Feb 42 min read
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.
Jon Ponting
Jan 302 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.
Jon Ponting
Jan 263 min read
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.
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.
Jon Ponting
Oct 19, 20252 min read
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.
Jon Ponting
Sep 21, 20251 min read
Why infrared heating has no impact on EPC ratings
I often get asked how Infrared panel heaters compare to standard convective heaters For Part L compliance. I know, I get asked all the fun questions!
Jon Ponting
Aug 31, 20251 min read
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.
Jon Ponting
Jun 1, 20252 min read
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