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Electric Radiators or Storage Heaters are they energy efficient?

The papers seem full of ads for electric radiators claiming to be cheap to run and energy efficient. Let’s take a look at the cheap to run element first – no pun intended!


Electricity is one of the most expensive forms of heating in the UK and emits the most CO2 emissions – unless you’re currently on a green tariff.  If you’ve bought or sold a house in the last eight years, you will know that it’s a legal requirement to have an energy rating for the property. This takes the form of an EPC (Energy Performance Certificate), and provides an A-G energy rating much the same as appears on your washing machine. The EPC crudely predicts the running costs of your house based on the levels of insulation, lighting systems, glazing, your heating system and controls. An EPC for a property fitted with an electric heating system will almost always be penalised, and have a lower A to G energy rating than the same as those fitted with a gas or even an oil boiler. Why? Well, simply because electricity is more expensive per kW hour to heat your home. Ironically, even if you had a super efficient ground or air source heat pump running your home, the EPC assessment would see a modern gas combi-boiler as being the more energy efficient. Even an up-to-date oil boiler would give a better EPC rating, and, at current oil prices, cost considerably less to run!

Storage Heaters Cost Calculator

So, getting back to the adverts, how can claims be made that electric radiators are energy efficient? Let’s take a look at what electric heating does; it converts electrical energy to heat (thermal energy). Electric space heating is almost 100% efficient as almost all purchased energy (15.5p per kW) is converted to heat, this applies to convector heaters, oil filled radiators and most portable electric heaters. However, what if that energy is more expensive in the first place? Electricity is nearly three times as expensive to use as gas! Top rated gas-condensing combi boilers are about 88% efficient, with the gas only costing 4.3p per kW. Electricity isn’t the most cost efficient way to heat your home.

Unlike energy efficient LED lighting where you can put in less electricity and get more light out, electric heating doesn’t allow you to get more thermal energy out than you put in the first place. This makes 1kW electric convector heaters as energy efficient as electric radiators, the only difference will be in how good the thermostatic controls and timer are at regulating their heat output. And more importantly how well insulated your home is!

Electric Heating Cost Calculator

The main difference between Electric Radiators and Storage Heaters is that the later use Economy 7, which is cheaper off peak electricity – usually about half the price of standard tariffs. Storage heaters store thermal energy in clay blocks overnight and then slowly release this during the day. Sounds good? The only problem is that come the evening, when you’re about to snuggle up in front of the tv, they tend to run out puff! So you’ll need backup heating of some kind. Now there’s a sting in the tail of Economy 7; the energy companies charge you more for daytime use of electricity. Plug in an electric fire and you’ll being paying double what your non Economy 7 neighbour is paying for their energy.

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So, are electric radiators a good choice? If you’ve got gas, or room for an oil tank, they are probably not for you. If your only choice is electricity then take a hard look at your energy usage and what you’re paying for your energy, then do the maths. Please remember to add on the cost of heating water with an immersion heater too. We’ve got lots of energy usage calculators to help with this. One thing that is worth factoring in is that electric heating doesn’t require yearly servicing like a boiler – saving you some cash and hassle. More importantly, stop loosing the heat you are paying for and insulate your home as best you can.

Electricity Cost Calculator

10 Responses to Electric Radiators or Storage Heaters are they energy efficient?

  1. Carol wakefield says:

    My elderly mother has recently moved into a one bedroom flat with storage heaters that are probably 20 years old. The flat is well insulated so keeping warm has not been the problem. The issue is the very high cost £120.00 a month! Does this sound right!

  2. S Pettifer says:

    “Unlike energy efficient LED lighting where you can put in less electricity and get more light out, electric heating doesn’t allow you to get more thermal energy out than you put in the first place” This is a bit disingenuous as you are implying that LEDs somehow miraculously let you get more light energy out than electrical energy put in. This is obviously bunk: They are just more efficient than the older filament bulbs (which lost a significant portion of input energy as heat) at converting the input energy to the desired output, and therefore this isn’t really a very good or valid comparison.

  3. Tony Renshaw says:

    Some points that have been missed: Storage heaters generally are rated at twice the wattage of a direct-acting electric radiator. A 3.5kw-4 kw storage heater can usually be replaced with a radiator of 1.6kw-2.0kw.

    Also, storage heaters draw their wattage for seven full hours overnight. A radiator only needs to draw power when each room is occupied and it’s thermostatic, so draws only the wattage required to meet the set temp.

    Radiators don’t release stored heat in the night when you don’t want it, or during the following day while you are out, or when the weather is mild. They also do not run-out of heat – Causing you to use “boost” on storage heaters, which is on the E7 “premium rate”

    Radiators heat more effectively through radiant heat as well as convected warm air, whereas storage heaters only convect, and also dry the air and burn dust.

  4. Ian McIntosh says:

    This is something we come accross quite a lot and it is very frustrating. What we have found out is that storage heaters will get the maximum score because they use economy 7, end of story. The EPC rating assumes that they will use 7 hours of electric at economy 7 whereas any other type of heater will use peak electric. There is no consideration given whatsoever to the fact that they will run out of heat early evening and you will need to put the convector on nor the fact that other types of heating have better thermostats or controls. With tehse “human intervention ” is required so is penalised!!

  5. G H Pegler says:

    I have changed from economy 7 to a fireclay filled electric radiator controlled by wireless thermostat and my meter changed to standard tariff, In 12months I have saved 25percent on my electric bill. An Energy Performance Certificate which I have just had to get states that I should go back to storage heaters as a recommended measure. The energy performance is given as one star out of a scale of 5 for my radiator.I would appreciate any observations.

    • David Smith says:

      I am in the process of investigating whether I should change my storage heaters to fire clay electric radiators, what make are the ones you have and how are you finding the costs, any advice would be appreciated

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