The term "ambient heat" refers to heat that is present in layers of air close to the ground, in surface bodies of water and in the ground a few metres below the surface, primarily through the storage of solar energy. It is a renewable and natural source of energy, because the heat is produced by solar energy and is thus constantly renewed.
Geothermal energy comes from a different source. Here, heat produced from the decay of naturally present radioactive elements is stored underground. The term "near-surface geothermal energy" refers to the use of heat from a depth of around 500 metres. It concerns the use of heat from groundwater reserves, as well as heat that is transported to heat pumps with the aid of geothermal probes. Thus near-surface geothermal energy has to be distinguished from the use of geothermal energy from much greater depths below ground. The temperatures at these depths can be used directly for heating, as well as for electricity production (depending on the depth).
Heat pumps are used in a variety of sectors today for a broad range of purposes. There is a great deal of potential for the use of ambient heat and near-surface geothermal energy, particularly for room heating and hot water production. Heat pump technology is making a valuable contribution towards the attainment of the declared energy and climate objectives.
The replacement of heating systems within the scope of building renovations is one of the ways in which these objectives can be achieved. By 2050, around 900,000 fossil-fuelled heating systems (status: 2019) will need to be renovated, and these could all be converted to heat pump technology. It is essential to promote the use of this technology and thus exploit the existing enormous potential.