Thermal impact of underground car parks on urban groundwater.

Built-up areas are known to heavily impact the thermal regime of the shallow subsurface. In many cities, the answer to densification is to increase the height and depth of buildings, which leads to a steady growth in the number of underground car parks. These underground car parks are heated by waste heat from car engines and are typically several degrees warmer than the surrounding subsurface, which makes them a heat source for ambient subsurface and groundwater.

Is thermal use of groundwater a pollution?

Thermal use of the shallow subsurface and its aquifers (< 400 m) is steadily increasing. Currently, more than 2800 aquifer thermal energy storage (ATES) systems are operating worldwide alongside more than 1.2 million ground source heat pump (GSHP) systems in Europe alone.