However, the green heart of The Circle can be found above all in the anergy network for supplying heat and cooling. Of the 1,150 piles in the foundation, 850 have been designed as energy piles. In summer, these transport excess heat underground where it is stored as energy. In winter, this heat can then be used for heating the building. External energy in the form of electricity is only required for operating the heat pumps and refrigerating units. Some of the electricity is also generated from solar power, with solar panels installed on all suitable roof surfaces.
The Circle is not only green at heart, but also has its own green lung, with 80,000 square metres of forest, meadows and marshland transformed into an airport park where travellers and residents alike can kick back and relax in the heart of nature.