XRG Simulation supported the municipal building management of the city of Bonn for the Hardtbergbad project through dynamic year-round simulations with the HVAC Library in order to examine the available renewable energy supply systems (heat pumps, photovoltaics, wastewater, heat recovery, etc.) in more detail. In addition to the heat generators and consumers, this also included a validated model of the outdoor pool as a heat storage facility. Based on the results of the simulations,concrete statements could be made regarding the energy