This Master Thesis attempts to answer the question how District heating Systems can lower the temperature within the return flow. The two District heating Systems of Friesenheim at Badenova in Germany and Skagen in Denmark were compared. As an initiating problem the return temperature in the Badenova district heating system is approx. 60° C, whereas in Skagen it is 40° C. A higher return temperature results in larger net losses, further on less energy stored in a thermal store and lower efficiency of heat production. These facts makes district heating less attractive. For each District Heating System the annual consumption was analysed and simulated. A detailed analysis about the already installed District Heating system was made to ensure that the energy can still be transported via the already existing pipes with using the lower temperatures. Further on the heat supply- as well as the substations were analysed if they can work more efficient by using the lower temperatures. Finally a plan was made how the return temperature can be lowered and a financial bonus plan was introduced to make this advantage more attractive to the consumers.