Baugemeinschaft Ettlingen has opted for a sustainable and energy-efficient BES system in its 3,300 m² new contruction project on Durlacher Strasse. Using a heating and cooling surface system in the flats, the BES system provides hot water, heating and cooling for the building with a combination of 100 m² of solar thermal collectors, heat pumps and 1100 m² of BES geothermal storage.