Running Costs of Electric Radiators and Electric Heaters

All electric heaters produce the same amount of heat for the same amount of electricity used and consequently, there is no difference in their operating costs. This is already supported by established science and a government paper, “The Government’s Standard Assessment Procedure for Energy Rating of Dwellings” (SAP 2012), which is published on behalf of the Department of Energy & Climate Change by Building Research Establishment (BRE).

The government document SAP 2012 was designed to evaluate the energy performance of dwellings and includes energy performance information about every aspect of the dwelling. It is used in the production of official Energy performance Certificates (EPCs) for properties. One of these aspects is heating and covers electric heaters. SAP 2012 recognises that all direct acting electric heaters are 100% efficient and therefore, the running cost and energy use of all direct acting electric heaters will be the same. Because of that, SAP 2012 does not identify any specific electric heater. Therefore SAP 2012 demonstrates that all electric heaters and electric radiators produce the same amount of heat by consuming equal amounts of energy without any price variations.

All electric heaters and electric radiators produce heat in the same way, by passing electricity through a resistance element. Joule’s law and the law of conservation of energy in physics has determined that such a method of producing heat, known as “Joule heating”, produces heat with 100% efficiency. There is a report which documents this – the preparatory study for local room heating products on behalf of the European Commission and we can highlight the statement, “Efficiency of electric heaters is determined by the Joule effect where all electricity is converted into heat. In practical terms, the product efficiency in electric heaters is 100%”.

To further prove this, Electrorad instructed an accredited domestic energy assessor to evaluate the energy efficiency of a property that was heated via electricity by following the SAP 2012 standard. The assessor used Electrorad Aeroflow radiators and Fischer Future Heat electric radiators. The EPCs showed that the estimated yearly energy consumption and running costs for both heating systems were the same. Furthermore, the overall energy efficiency rating of the property remained the same with both heating systems. This would be the result for any electric heater or electric radiator from any manufacturer as they are all considered to have the same efficiency – 100%.

BRE provided a statement for us, BRE are responsible for writing energy efficiency standards for the government, including SAP 2012. BRE stated that the energy consumption for all electric heaters and electric radiators would be the same, primarily because all electric heating was 100% efficient. BRE stated that all electric heaters (except heat pumps) had an output of 1 kWh of heat when provided with 1 kWh of electricity. They explained that this was long-established basic physics and was the reason why SAP 2012 did not require the input of test data on the efficiency of electric heating systems (except heat pumps). BRE further stated that there were differences in the controllability of different electric heating products, which could affect energy use. Because of that, SAP 2012 differentiated between those electric heaters which had thermostatic control and those which did not. However, BRE stated that in practice all new electric heaters had such a mechanism and therefore the energy consumption for all electric heaters would be the same.

The accuracy of a thermostat will serve to produce better comfort by maintaining a more accurate room temperature, but will not however, change the efficiency of the electrical heating appliance, which is the position taken in SAP 2012.

If we refer to the document ‘Running Costs of Conventional Electric Space Heating’ written by Dr John Counsell, we can quote the statement: “In the study three types of 100% efficient electric heating systems have been modelled using SAP2012 … In SAP modelling all these heaters have the same responsiveness and controllability and there is NO variation in running cost predictions in SAP2012 between these systems …”.

In the Energy Saving Trust report – ‘Domestic Heating By Electricity’, which promotes energy efficiency we can quote the following text, “… conversion efficiency of delivered to useful energy is very high for electric heating, and can normally be taken as 100 per cent irrespective of the type or make of appliance used”

The bottom line is that all electric radiators and electric heaters cost the same to run and use the same energy regardless of the type of materials used in construction and regardless of the use of oil / thermal fluid / gel / fireclay etc internally.

1kwh of electrical energy in = 1kwh of heat out