In order to achieve a climate-neutral building stock, its heat demand must be reduced and the remaining demand must be covered as completely as possible by renewable energies (RE). In order to use the supply from RE, such as solar thermal, to meet the demand, the heat must be stored. Currently, water-filled metal cylinders, so-called buffer storage tanks, are used almost exclusively for this purpose. Their size increases with the increasing share of RE, such as solar thermal for single-family homes, to several cubic meters. In the concept of the energy supporting structure, massive load-bearing building components, such as exterior walls of single-family houses, are used for heat storage and transfer and connected to the heating system via thermal activation, see figure above. Since the building parts have active energetic functions in addition to their static-constructive functions, they are referred to as "multifunctional building parts" (MBP) and the entire concept as 'energy supporting structure'
In order to use the MBP in practice, they must be integrated into the heating system. The aim of this concept is to minimise the size of the buffer storage and to increase the share of RE in the heat demand. A concept for solar thermal energy additionally uses a heat pump to ensure heat generation, see lower figure . The temperature is controlled primarily via the MBP by charging them directly or indirectly with solar heat via the buffer storage. The remaining heating demand is covered by the underfloor heating. The temperature difference between the MBP and the interior increases due to the loading of the MBP and the heat is transferred to the interior with a time delay.