District heating for building applications will need integrated thermal energy storage systems in order to be able to include more renewable energy into their operation. Thermal energy storage models are nowadays lacking accuracy or need too much calculation time, to be able to use them for district heating network topology optimization. They show the same deficiencies when control during operation is considered. This project aims at developing fast and reliable models for thermal energy storage systems and integrate them into district heating models. Secondly the project aims to develop an heuristic topology optimization method which will allow to design quickly and reliably a district heating network with thermal energy storage. In a final phase the thermal models will be used to define control strategies for district heating networks by simulation in Modelica.