Considering the overall heating demand in Austria the share of district heating accounts for 25 % and about triplecated since 1990. Nevertheless the development over the last years was less fast than before in respect to sold heat as well as newly installed lines (increasing from 4 900 km in the year 2013 to about 5 400 km in 2016). The reason for this mainly lies in the fact that in the meantime many of the dense city centers and quartiers already are supplied with district heating networks. Moreover the heating demand decreases due to better insulated building standards for newly built houses as well as renovated buildings. Therefore the energy demand per meter of constructed line decreases. This leads to an increase in specific heating losses and thus changes the framework conditions of heating networks in respect to economic feasibility, tariffs and expansion strategies. Classical district heating systems with high temperature levels therefore face limitations.

New district heating network strategies with adapted temperature levels as well as spread production and storage structures with smart control algorithms show completely new possibilities for increasing construction of district heating networks as well as integrating renewables. Recently some projects based on „anergy networks“ and „cold district heating networks“ respectively have been developed. First experiences are available showing the big potential of such networks. Heating networks with low temperature levels and networks using the return flow increasingly get interesting for suppliers. On the one hand the complexity of these systems increases due to new network designs, decentralisation, coupling of energy sectors and new control systems. On the other hand new systems have to be operated in an economically feasible way to be competitive. Both aspects require new simulation and modelling tools that are presented in the new issue of „nachhaltige technologien“.