This study aimed demonstrate the energy-saving performance of an exhaust heat recovery system using a heat recovery heat pump in a large-scale hospital in a cold region, where it is difficult to construct a highly efficient heat source system. First, the effect of introducing the exhaust heat recovery system was analyzed, and the effect of the system efficiency improvement on the thermal load was inferred from the evaluation of the combined heat source facilities for air-conditioning and hot water supply. Next, the impact of optimizing operational settings on energy efficiency was evaluated. The results indicated that the energy efficiency may be improved by optimizing the control setting temperature of the exhaust heat recovery systems.

In Ishikari Bay near Sapporo, 10 projects are planned to generate 11 GW of offshore wind power, with 112 MW of wind power partially put into operation in January 2024. The applications of offshore wind power generation remain undecided, and supplying of electricity to Tokyo via submarine cables and other means is being planned. On the other hand, this study assumes local production for local consumption of electricity, and considers supplying electricity generated in Ishikari Bay to Sapporo, a major consumer of electricity and heat, by interconnecting it with the surrounding onshore variable renewable energy sources. However, the maximum output of the regulating power to stabilize supply-demand fluctuations and the capacity of the regulating power to stabilize the daily disparity are unknown. This study elucidates the maximum output and storage capacity when ammonia, methylcyclohexane, hydrogen, and sodium sulfur batteries are introduced as the regulating power.

Chamber boxes are widely used in duct systems for air conditioning and ventilation; however, the optimal method for accurately predicting pressure drop has not been clarified. Here, various methods for predicting the pressure drop in chamber boxes were compared with those of the experimental results and computational fluid dynamics (CFD) simulations. The results showed that the proposed method, which sums the pressure drops at a duct outlet and inlet, had the highest prediction accuracy. This method is convenient as it does not require the chamber box dimensions. For in-line chamber boxes, this method yields a higher pressure drop than that in the experimental and CFD results, making it safer; however, a method for calculating closer values was also proposed.

Sewage heat is gaining attention as an underutilized energy source, with expectations for its integration alongside the rehabilitation of aging sewer pipelines. To facilitate the broader introduction of sewage heat, it is essential to gather sewage data　from small and medium-sized sewage pipelines in local cities and evaluate the systems currently in operation. In this study, we analyzed the performance of a sewage-heat-utilization heat pump installed in a hospital located in a cold district. Our analysis is based on sewage temperature measurements and Building Energy Management System (BEMS) data. Additionally, we calculated the annual primary energy consumption using real values and compared it with that of an air-cooled system.