An energy and economic comparison of air-source 5GDHC networks with alternative technologies in existing districts

5th generation district heating and cooling (5GDHC) networks have experienced a vast boost in newly built residential districts. High shares of cooling demands as waste heat sources to the network and correspondingly high demand overlaps are often reported as key factors for their feasibility. For a roll out of the concept of 5GDHC networks into heating-dominated existing building stock, technical and non-technical requirements apply which may not be valid in newly built districts. In addition, shares of cooling demands as waste heat sources to the network and correspondingly high demand overlaps are most often not present in heating-dominated climates and residential areas. (i) A summary of technical requirements for 5GDHC networks in existing districts is given which need to be met or at least considered in its planning. (ii) In a simulation-based techno-economic analysis a 5GDHC system is compared to an insulated 4th generation district heating (4GDH) network and individual, decentralized air-source heat pumps at varied linear heat density. All examined systems rely on ambient air as the main heat source. Besides the line density, varied input parameters comprise the proportion of cooling demand and the installed PV capacity in rural and municipal districts. 5GDHC networks attain lower electricity imports than 4GDH networks even in absence of continuously available environmental heat sources other than ambient air, PV generation or elevated space cooling demands. Economic advantages over 4GDH networks in the defined setup are observed for low line densities in both district characteristics under the specified cost structure and modelling assumptions.