Do heat pumps actually work in cold weather?

Heat pumps can be used to provide climate-friendly heat to buildings, both old and new. What what happens when temperatures go down in winter? Will the heat pumps continue to work? Find out more about climate-friendly heating during the cold season below.

Illustration: Haus unter einer Lupe© BMWK

Do heat pumps continue to work when it is very cold outside?

Heat pumps are reliable providers of heat, even when temperatures fall below zero outside. Air, water and the ground still have a higher temperature than the refrigerant in the heat exchanger. This means that heat continues to flow from its source to the refrigerant and can then be transported on to the building. Water and and the ground maintain relatively high temperatures all year round. But very cold air, too, can be used as a source of heating. This allows air source heat pumps to be used in cold regions such as Scandinavia or the Arctic.

A heat pump can supply a building with all the heat it needs, especially if the building has been insulated. In order to reduce investment costs, consumers can opt for a heat pump performance that is not adapted to very cold days (as these are rare) and to integrate electric resistance heating coils (auxiliary heating), which will be activated automatically in extremely low temperatures to support the heat pump system.

Hybrid heat pumps in buildings which are less well insulated

Hybrid heat pumps are suitable for less well insulated buildings. Hybrid heat pumps use a heat pump alongside a fossil-fuel heating system (for example an existing gas boiler), which supports the heat pump system on particularly cold days. If the building’s outer shell is renovated and the building’s efficiency improved at some point in the future, this boiler can be shut down.
If most of the electricity used to operate the heat pump comes from renewable sources, for example from a roof-top solar system, this will make the building’s heat supply almost greenhouse-gas neutral.

Such a set-up also reduces heating costs to a minimum. But even if the required electricity is taken from the grid, heat pumps have the potential to make a building’s heat supply greenhouse-gas neutral. This is because Germany has committed itself to generate all its electricity from renewables by 2035. This makes heat pumps a very climate-friendly heating option.

Detailed information surrounding the suitability of heat pumps for your home (German only), their installation and use, and the funding you may benefit from can be found on (in German only).