High Heat Retention Storage Heaters

At the time of writing the methodology for EPC assessments of existing dwellings is RDSAP 9.94. The much anticipated RDSAP 10 update has not happened yet and a significant methodology overhaul from RDSAP to the Hone Energy Model (HEM) is proposed for 2025.

Storage Heaters are often seen as an attractive option for properties that don’t have a mains gas supply available.

In the absense of a more economic fuel type in such a property, storage heaters make the best use of electricity they can by heating up high density bricks during the night time when lower cost electricity is available, and releasing that heat throughout the day.

Although somewhat less than ideal from a domestic EPC perspective due to the generally high cost of electricity as a fuel type, even when effectively powering a 100% efficient device, they are fitted to many properties, and as a product have undergone some development over the years.

We'll cover High Heat Retention Storage Heaters on this page but also discuss alternatives, in the context of a property that only has an electric supply currently (ie no gas).

Nowadays, with heat pumps becoming more affordable and grants available for their installation, combined with their performance being around the 400% mark when systems are designed and installed to a good standard, storage heaters are likely to fall out of favour to heat pumps moving forwards.

Early storage heaters were large bulky unattractive boxes, modern ones became thinner and more attractive, and included automatic charge controls, and then fan assisted storage heaters became a recommended upgrade on EPC certificates a few years ago,

Nowadays, High Heat Retention Storage Heaters are the best performing variant, and are likely to be seen in EPC recommendations if you already have earlier types of storage heater in your property.

In order to successfully enter a High Heat Retention Storage Heater in an EPC assessment, the Energy Assessor needs to locate the specific make and model from a list in the Product Characteristics Database (PCDB).

If your device is not on the list, it cannot be entered as a High Heat Retention Storage Heater.

To check if a model is listed in the PCDB, click on the link below and go into the High Heat Retention Storage Heaters section:

https://www.ncm-pcdb.org.uk/sap/searchpod.jsp?id=17

At the time of writing this section (Sep 2024), there are only 45 available models of HHRSHs currently listed in the PCDB:

• Dimplex Quantum: QM050, QM070, QM100, QM125, QM150, QM050RF, QM070RF, QM100RF, QM125RF, QM150RF
• Creda Quantum: CQH 070, CQH 100, CQH 125, CQH 150
• Heatstore Quantum: HSDQ 070, HSDQ 100, HSDQ 125, HSDQ 150
• Heatstore Dynamic HHR: HSDHHR050, HSDHHR070, HSDHHR100, HSDHHR125, HSDHHR150
• Gabarron Ecombi HHR: ECOHHR10, ECOHHR20, ECOHHR30, ECOHHR40
• Gabarron Solar HHR: SOLARHHR10, SOLARHHR20, SOLARHHR30, SOLARHHR40
• Stiebel Eltron: SHF 2000, SHS 2400, SHS 3600, SHF 3000, SHS 2000
• Haverland Eco-Joule-1: SHV1700HHR, SHV2250HHR, SHV3400HHR
• Fischer Elektrostore: HHR16, HHR25, HHR34

If the heater you are looking to install is not on this list then your EPC won’t be better that if you had 'standard' storage heaters present.

The new labour government of 2024 has indicated their intention to tighten the the MEES requirement for rented properties to Band C by 2030.

Perhaps you're interested in updating or upgrading your storage heaters to improve your EPC rating because of this legislation.

If so, what do you do?

Here are some options:

• Upgrade your existing storage heaters to High Heat Retention Storage Heaters.
• Rip out the storage heaters, get gas connected to the property and fit a gas boiler and radiators / underfloor heating
• Rip out the storage heaters and fit an air source heat pump with radiators / underfloor heating
• Rip out the storage heaters and fit an oil boiler and radiators / underfloor heating.
• Rip out the storage heaters and fit electric panel heaters instead because you’ve seen a very convincing advert on social media from a company saying that their peak-rate electric panel heaters are better than storage heaters.

In case the last option in the list above didn’t jump out at you, we'll cover it here first! It’s included in humour, in the sense that it's the option you want to avoid at all costs.

However, it's included seriously because there are companies that actively advertise, particularly on social media, trying to sell this type of heater to people that currently have storage heaters. They try to dupe you into purchasing their products by describing them as highly efficient electric panel heaters.

Here's an example marketing ploy:

"Electric Radiators offer a modern, energy efficient heating solution for any space. Unlike traditional radiators, electric radiators provide 100% conversion of energy to heat, precise temperature control for each room and the latest energy saving technology, ensuring optimal comfort and reducing energy wastage."

In fact, if you replace storage heaters with electric panel heaters, whatever the company tells you, your EPC rating will fall. This is beacuse the panel heaters will be seen to use peak rate electricity for heating during the day, and it will therefore cost more to maintain a property at a comfortable temperature, compared to storage heaters which charge up using only cheap rate electricity during the night.

Here are the EPC ratings for my house, a 1950s mid-terrace (see our Case Study 2 page for more info), comparing storage heaters with electric panel heaters (note that I have no form of Secondary Heating present in the property):

So, for example, if I were to move from 'modern slimline storage heaters' to 'electric panel heaters' as the main form of heating in my property, this would reduce my EPC rating from 46E to 38F.

In contrast, moving to 'high heat retention storage heaters' instead would take me up to a 58D. That would still however be 11 SAP points short of a C-band rating for my property.

Always contact a Domestic Energy Assessor to understand the implications for the EPC rating of your own property, as there are many factors that combine to affect the results.

When you see a recommendation on your EPC for High Heat Retention Storage Heaters, an estimate of the cost will be provided. You should take this with a pinch of salt however and get a worked estimate from an electrician instead before seriously considering this as an option.

If you carry out your own research online, you'll see for example that Dimplex Quantum High Heat Retention Storage Heaters are advertised with a retail price of around 1,000 GBP each, that's just for one heater, and does not include installation.

Installation will be an additional cost, and they might require additional wiring when replacing older storage heaters. High Heat Retention Storage Heaters generally require both a peak rate and an off-peak rate electrical supply, for each heater. Previous storage heaters are likely to only have had an off-peak electric supply present.

If you need to replace/install several storage heaters then the cost will mount up quickly, and you may instead want to consider another option, one perhaps that could increase your EPC rating even further.

Note that you need to make sure all of your 'Habitable Rooms' in your property are heated, and any other form of peak-rate electrical heating (panel heaters, fixed fan heaters, electric towel rail radiators etc) are removed - See our Heating Systems page for more information about how this affects an EPC rating.

In the table from the section above, we can see that if I were to currently have modern slimline storage heaters, and upgrade them to High Heat Retention Storage heaters, my EPC rating would move from 46E to 58D.

That's quite a nice improvement, but it would still leave me 11 SAP points short of a C-band rating, if that was my goal, and I could get a better EPC rating improvement by moving to a gas combi boiler instead.

Remember to always approach a Domestic Energy Assessor before making changes to your property to see what difference those changes would make to your EPC rating. You'll be making decisions then from a position of certainty, rather than spending significant amounts of money and not really knowing what the outcome would be.

You won’t see a recommendation on your EPC to upgrade to a gas combi-boiler if you currently don’t have a gas supply to your property.

It might be possible however to get gas connected to the property, so bear that in mind when considering your options. One such option could be to fit a condensing gas boiler and radiator/underfloor heating system.

This of course won't take you down the ideal path of reducing carbon emissions, but currently domestic EPCs are more centered around the cost of the fuel for heating rather than the CO2 emissions. This is in contrast to EPCs for commercial premises which are more centeered around CO2 emissions.

If you do get a gas boiler system installed including radiators, at least you would be further down the path to swap that gas boiler out for a Heat Pump next time round.

I was in this position with my property, which had old electric storage heaters back in 2015. The EPC rating was 43E. There was no gas supply to the property, although evidence of a previous gas meter was visible.

We contacted the local supplier who fitted a new gas supply connection, and we then fitted a gas combi boiler with radiators. This brought our EPC rating up to 68D, one point short of a C-Band rating.

If you have a flat, with no gas present, it might be harder, particularly if you are not on the ground floor. Do still enquire with local suppliers though as you can then work from a position of certainty. You might be surprised that this is actually an available option.

If you have a property in a small village, it might be harder still, or at least more expensive.

This could be more of an option compared to installing gas to a property that currently has electric storage heaters.

Click here to return to our 'Improve Your EPC' main page, and see if there is another way you could improve your EPC rating.