Third energy source are the natural geothermal warm water deposits. Drillings into the earth allow a direct feeding of clean, hot water from the underground. This geothermal energy can likewise serve the generation of current. Projects for the Deep Heat Mining are already in preparation (1996 launched by the Federal Office for energy). Outgoing of it that a Wellnesskomplex with large, to heating baths is planned, then the building of a combined heat pump system makes sense.

As the fourth alternative energy source, the large, concave glass roof is applicable. Half light permeable it bundles the radiation on a hydra and heats this up. The rain water collected in the curvature can be used for the WC flushings, for the autowash road and for the plantings.