2025 Volume 50 Issue 344 Pages 11-20
Fifth-generation district heating and cooling systems are systems that connects the pipes through which low-temperature heat source water flows to multiple buildings. They use water source heat pumps installed in each building to meet the demand for cold and hot heat. There is substantial body of research on 5GDHC systems for cold climates, but the effects of introducing them in a warm climate such as that of Japan have not been clarified. In this study, the characteristics of 5GDHC systems were determined through simulations using the climate conditions and heat load characteristics of Tokyo. In addition, the energy performance was investigated from the perspective of the amount of heat processed and electricity consumption, and the effects of introducing a 5GDHC system in Japan were clarified. The amount of heat processed by the plant was greatly reduced during the transitional period when cooling and heating were used together. In addition, the amount of electricity consumed by the plant during heating operations, which accounted for a large proportion of the electricity consumption in the baseline model, was almost zero with the introduction of the heat collection panels and thermal storage tank. The case study showed that changing the value of the water temperature set in the pipes improves system efficiency, and that even for groups of customers with unbalanced loads, the system can be operated using less electricity than if a plant is installed for each building. From the above considerations, it was possible to demonstrate that the deployment of a 5GDHC system is feasible even in Japan. In the future, we will consider cases where heat is supplied to more customers and we will address how to reduce electricity consumption in summer by using the temperature difference between seawater and river water.
