Energy performance of an innovative centralized thermal system for domestic hot water production: Comparative analysis for mild and cold climates

This study evaluates the energy performance of an innovative Domestic Hot Water (DHW) system, termed e-THERM, which combines a centralized air-to-water heat pump using propane (R290), photovoltaic modules with battery storage, and a hybrid thermal storage configuration consisting of a centralized storage tank and decentralized storage units installed within individual dwellings. The system was assessed through dynamic TRNSYS simulations using a renovated multifamily residential building as a case study under two contrasting climatic conditions: the mild climate of Catania (Italy) and the cold climate of Ottawa (Canada). Its performance was compared with that of a conventional centralized DHW system. In addition, the contribution of DHW production to the overall building energy demand was evaluated for both climatic contexts to assess the potential impact of improving DHW efficiency in the residential sector. The analysis evaluated key performance indicators, including electricity consumption, heat losses, heat pump operating time, and the seasonal coefficient of performance (SCOP), providing a comprehensive assessment of the system's energy performance and operational behaviour. The comparison between the two system configurations and climatic conditions enabled evaluation of the proposed solution's adaptability across different operating environments. The results indicate that the e-THERM system increases the SCOP by approximately 20%, reduces total electricity consumption by about 25%, and lowers non-renewable energy use by 50–70% compared with the conventional centralized system under both climatic conditions. Overall, the findings demonstrate that integrating decentralized thermal storage with advanced control strategies can substantially improve the energy efficiency of centralized DHW systems in multifamily residential buildings.