Physical basics in heating with electricity

There are various prejudices about electric heating: inefficient, expensive, ineffective. You can read in this article which physical principles actually apply to heating with electricity and how the efficiency of electricity heating can be derived from this.

Resistance heating principle

The fact that electricity can be used for heating is based on the law of electrical resistance. It is also called Ohm's law after its discoverer. The physical unit that is used for the resistance of an electrical conductor is the ohm. 1 ? corresponds to 1 V / A (volts per ampere).

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Working principle of electrical resistance

Current flow is based on the movement of electrons. However, each conductor has a certain resistance to the movement of the electrons. This means that part of the energy is no longer transported, but is converted into thermal energy.

The resistance values of individual substances are different. The cross-section of the conductor also plays an important role. In addition, the temperature also has an influence on the level of resistance of a conductor.

Appropriate construction creates conductors that have a particularly high resistance. This can be the following components:

  • Heating conductor (a simple, high-resistance wire)
  • Heating coil (a coiled wire, which has a higher resistance as a result)
  • Heating tape
  • Heating jacket
  • Heating tape
  • Heating register
  • or special resistance elements


The conversion of the applied electricity into heat takes place almost without any losses. Electric heating is therefore quite efficient. From a physical point of view, it is by no means true that electric heating systems work inefficiently. With electric heating, however, you always have to consider the overall efficiency.

Other possibilities

Storage heaters

Not every electric heater is a resistance heater. In addition to direct heating, there is also storage heating (such as night storage heating). Memory losses can also occur here, which must be taken into account physically and technically.

Heat pump

The heat pump also uses electricity to generate heat. The operating principle here is more similar to a refrigerator: heat is extracted from a medium (air, groundwater or the ground), just as the refrigerator does with the food it contains.

The heat is then given off to the air or a liquid. In the ideal case, for example in carefully designed geothermal systems, the heat yield can be many times the electrical energy used.

Radiant heating

With radiant heating, such as infrared heating, electricity is also converted into thermal energy. Here, however, it is not convection heat that is generated, but thermal radiation, similar to the warming radiation of the sun when it hits the earth.

The efficiency of radiant heating is extremely high - it is around 2.5 times that of a modern gas condensing boiler. From a technical point of view, radiant heating is therefore one of the most advanced and future-oriented technologies for warming a room.

The only problem here is the ecological balance when heating with electricity. For the assessment of the total efficiency, the efficiency of electricity recovery must also be included in the electricity of electricity, but also the electricity recovery has some adverse ecological effects.