Air/water heat pumps have seen extraordinary market growth during the last decade. The total number of air/water heat pump units sold in Europe, for example, increased from 36.707 units sold in 2005 to a number of 208.255 units sold in 2008, which is an increase of a factor of 6 in three years.
These figures clearly demonstrate the future significance of this heat pump type. Air/water heat pumps are successful as they are considerably cheaper than ground-coupled heat pumps, and much easier to install than ground-coupled heat pumps, as they do not need boreholes or surface areas for ground-coupled horizontal collectors. These features make air/water heat pumps attractive candidates for applications where the installation of ground-coupled heat sources is difficult or not even possible.
This is typically the case for existing buildings, especially when situated in densely populated areas and cities. For these reasons, the project consortium believes that larger scale air/water heat pumps will be an important, integrative component of the energy infrastructure in cities in the future.