Heat pumps get 60-80 percent of their energy from the environment without straining it. The rest of the energy usually comes from the wall socket. Heat pumps heat in a climate-neutral way if they use green energy.

But even with the current electricity mix, heating with a heat pump is less harmful to the climate than conventional heating. Because heating with gas and oil releases a lot of CO2 – far too much.

Heating with electricity can be climate neutral if it is exclusively green energy. This is very expensive.

types of heat pumps

The amount of electricity consumed during operation depends on the type of heat pump. Although air-to-water heat pumps are the most installed, they are the least efficient. They produce three kilowatt hours of heat from one kilowatt hour of electricity.

The annual performance factor (SPF) tells you how high the share of electricity is in the amount of heat generated. Or to put it another way: how much heat can be produced with how much electricity.

Geothermal heat pumps generate four to five kilowatt hours of heat from one kilowatt hour of electricity. The reason is that the refrigerant can absorb more heat from the environment because the temperatures in the ground during the winter heating period are higher than in the air.

Heat pumps that extract energy from groundwater have to pump it to the surface. Here are two opposing effects: Due to the high temperature of the water, the energy gain is high. But pumping also ensures that energy is lost again. The specific situation is best assessed by a specialist on site. Some water-to-water heat pumps have an annual performance factor of five.

Above all, a heat pump needs energy to compress the refrigerant and thus bring it up to the high temperatures required by heating. The electricity is therefore not used for heating. In the linked article I explained how a heat pump works in principle.

state of the house

The type of heat pump determines how much energy is absorbed from the environment. However, the nature of the apartment or house determines the extent to which the water in the stove should be heated.

This supply temperature must be high if a lot of heat is lost through walls and windows or if the radiators are so small that they hardly have a surface to give off heat. With high insulation and large radiators, the heat pump does not have to work as hard.

New buildings are generally well insulated. Post-war buildings can also be insulated from the outside afterwards. In older old buildings, this is only possible at the rear, because the facade at the front is not smooth or is even listed as a monument.

If a lot of heat is lost, a lot of heat has to be added to maintain the room temperature. The best way to do this is with large area radiators. Usually this concerns underfloor heating. This continuously gives off some heat to the room over a large surface.

The flow temperature does not have to be so high, so that the heat pump draws less power during compression. Nevertheless: The energy loss in poorly insulated houses is real and must be compensated. The heat pump in an old building runs continuously and therefore consumes more electricity than in a well-insulated new building.

combination with photovoltaics

If a conversion is already pending, why not go for the big fix right away? A photovoltaic system on the roof that generates electricity in a climate-neutral way is a good addition to the heat pump, which does not use gas or fuel oil but needs more electricity.

At first sight, buying green electricity to make the heat pump work seems sufficient for climate-neutral heating. But the electricity supplier does not install a new wind turbine for every new green energy contract.

If one switches from conventional electricity to green energy, the other usually receives a more climate-damaging electricity mix as compensation. Only when a coal or gas-fired power plant is shut down does the environment benefit. The chance increases if more and more households produce their own green electricity on the roof.

The catch: in the summer, when the sun is shining, a photovoltaic installation produces the most electricity. But a heat pump needs this almost exclusively in winter. Long-term storage doesn’t work yet. So in the summer the electricity flows to the general grid, while in the winter it has to be purchased at a higher price.

Nevertheless, it is worthwhile to combine both systems. Electricity costs are going down. But above all, the environment benefits – from both systems.

Conclusion: it depends

Installing a heat pump helps the environment. No fuel oil or gas is burned. A heat pump gets 60-80 percent of its energy from the environment, the so-called ambient heat. It only requires a little electricity, which is green power at best.

The efficiency of the heat pump and how much electricity is actually needed depends on several factors: the type of heat pump and the condition of the home. Anyone who gets heat from the earth and not out of desire and who also heats a well-insulated house, possibly with underfloor heating, does not have to pay a lot of electricity to keep it nice and warm at home.

Featured Image: Pixabay/Gerd Altmann