A numerical model for the energy assessment of a fifth-generation district heating and cooling (5GDHC) network

Achieving the new energy efficiency targets set by recent European directives is not a foregone conclusion for most new building construction projects. The regulatory limits are increasingly stringent and the energy design of buildings becomes more complex and detailed. The transition process towards nearly Zero Energy Buildings (nZEB) now affects almost all European countries, and will be the subject of future challenges in the construction sector. To overcome this problem, not only the role of individual buildings will be crucial, but also the function of future districts, whose cooperation in terms of energy exchange and sharing of resources could be a key aspect to face climate change in a sustainable and efficient way. In this context, a recently studied topic is represented by the fifth generation of low temperature district heating and cooling (5GDHC) networks. The potential of this new generation of thermal networks is to operate at low temperatures, usually below 25 °C, in order to be used as a heat source for the operation of reversible heat pumps, capable of satisfying both heating and cooling needs of the users connected to the network. This feature allows the network users to be prosumers, sharing the heat produced or removed from the network to generate a benefit for other users. Furthermore, this new generation of thermal networks allows an effective integration of renewable sources and low temperature waste heat sources, which can easily be integrated into the network. In this work, a dynamic numerical model has been developed in order to simulate the behaviour of a 5GDHC. A simulation scenario has been defined consisting of 15 different users belonging to the same district and their interaction within the network has been studied. The energy performance of the network was assessed by means of some global performance indexes, with the aim of characterizing the energy potential and response of the network. Thanks to the results presented in this work, it is possible to understand the positive effects of 5GDHC networks, encouraging the spread of this technology and its future application developments.