Geothermal planning maps based on geophysical measurements

The use of near surface geothermal energy is not based on the temperature increase with increasing depth, but on the fact that under normal conditions no seasonal temperature differences are present at depths exceeding 10 m. Below that depth temperatures are 10 - 12°C all over the year. So subsurface temperatures are cooler in summer and warmer in the winter than surface temperature. This can be used for cooling purposes in the summer, and, using a heat pump, for heating in the winter (Fig. 1).