4th generation district heating

Lowering temperatures in district heating supply (4th generation district heating) increases the efficiency of energy supply because network losses are reduced and the efficiency of heat generators increases. In addition, the possibilities for integrating renewable heat sources such as solar thermal or waste heat improve. Low network temperatures in both the flow and the return are only possible if the heat supply to the buildings can still be guaranteed. Therefore, buildings and grids must always be considered as one system when considering lowering the temperatures. The supply temperature is set centrally at the power plant and depends on the building with the highest temperature demand. The return temperature of the network results from the return temperatures of the individual consumers and is thus influenced by the control of the heating and ventilation systems in the buildings.

It is investigated which measures should be implemented in which buildings in order to reduce the temperatures as much as possible at low costs. First analyses regarding the return temperature show that a few buildings strongly increase the return temperature of the whole network, while the majority already has the desired low temperatures. In the further course of the research project, individual measures for return temperature reduction will be implemented and their effects evaluated.