Potentials and restrictions of grid bound heat and cold systems in urban quarters.

Conurbations are growing. Frequently, growth is still associated with increased energy consumption and higher environmental impacts. At the same time, major climate-protection efforts and a consistent transformation of the energy system are an imperative in the light of the Paris Agreement. Concerning internal and external urban development – meaning conversion and densification of existing built structures as well as extension in fringe areas – some issues with respect to the choice of appropriate technological networks for heat and power supply have not yet been clarified sufficiently. On the one hand, it is possible to generate surplus energy from plus energy houses that, however, does not necessarily correspond to the respective energy demand considering spatio-temporal aspects. On the other hand, urban areas dispose over considerable waste heat potentials from power generation, waste incineration, industry and wastewater treatment infrastructure that can be exploited via district heating systems. In this area of conflict, energy-oriented urban planning and urban design has to be implemented considering urban structure, technological options, economic considerations, environmental and climate protection as well as resilience to energy crisis. Under these complex circumstances several questions arise concerning grid-bound heating and cooling systems: (1) Are grid-bound energy systems sustainable in the long-run, especially when considering possibilities of decentralized energy supply (e.g. solar energy, geothermal, waste-heat recovery etc.)? (2) If yes, which forms of grid-bound energy supply should be prioritized (district heating versus gas grid)? (3) If one or both grids are already present in an area, is it meaningful to dismantle or decommission one of the systems taking energy- and material-flow perspectives as well as resilience aspects into account? (4) How does the prosumer-issue influence grid design as the necessity might emerge to either store electricity and heat surpluses or discharge them via grids? The project Eco.District.Heat provides strategic decision-making support for grid-bound energy systems of Austrian urban areas. Based on a system analysis a typology of urban patterns will be configured which represents different structural aspects. Applying scenario technique, building construction and energy technology parameters will be varied. The developed types of urban patterns including the scenarios will be characterized from an energy and material-flow perspective and appraised concerning environmental and economic impacts. This typology of urban patterns will be elaborated as toolbox to model existing or planned urban neighbourhoods and analyse them with quantitative and qualitative criteria concerning their potential to provide long-term supply with grid bound heating and cooling.