Electric heat pumps

Highly efficient renewable heating

A heat pump uses the renewable energy stored in the soil, groundwater or the environment for heating purposes. The most common are electric heat pumps. However, another efficient type of heat pump is  the gas heat pump (see here)

 A heat pump operates like a refrigerator in reverse: a refrigerant extracts low-temperature heat from the environment, which causes the refrigerant in the system to evaporate; the refrigerant is then compressed;  heat is released in a condenser and is transferred to the water circulating in the heating system.

Heat pumps work most efficiently to guarantee a high level of comfort when:

  • the heat source temperature (soil / groundwater / air) is higher, and
  • when combined with distribution systems that work at low temperature (e.g. underfloor heating).

Modern heat pumps can be used for space heating, domestic hot water, ventilating and cooling a building, depending on the technology. They work very quietly and are virtually maintenance-free.

Closed-loop heat pumps: ground source heat pumps or brine/water

Closed-loop heat pumps are the most common type heat pumps in new buildings, and the most efficient. They use a closed loop of pipe containing a water and anti-freeze solution to extract heat from the ground or groundwater; they are often referred to as ground-source, geothermal or “brine/water” heat pumps. The heat is transferred to water for distribution in the building. The heat can be extracted from the ground or ground water using vertical collectors in boreholes or loops of pipes laid horizontally below the surface of the ground.

Open-loop heat pumps: water/water

Open-loop heat pumps use the almost uniformly level temperature of water. The water from the source is pumped through the actual heat pump itself where its heat is extracted.

Air-source heat pumps: air/water

Air-source heat pumps extract environmental heat from the air. They are particularly suitable for installation in existing buildings and can be installed indoor or outdoor. They are easier and less costly to install as no boreholes or horizontal pipes are necessary.


  • Using renewable heat from the surroundings
  • Highly energy efficient
  • Can provide space heating, cooling and/or hot water
  • Suitable for different building contexts, especially in new builds
  • Reducing CO2 emissions, near zero if fully powered by renewable electricity (e.g. wind power or photovoltaics)