Domestic Hot Water Production in Residential Buildings: Energetic Analysis of Different Systems Through Dynamic Simulations

The energy used for Domestic Hot Water (DHW) production currently accounts for approximately 15–40% of the total energy needed in residential buildings. The present study deals with the energetic optimization of the Domestic Hot Water (DHW) system in a residential building of 10 apartments in Bologna, Italy. Two different systems are analyzed: the first has one centralized tank storage and a circulation loop, and the second has specific decentralized tanks (one for each apartment) with an internal heat exchanger. In both systems, the water is heated by an Electrical Heat Pump (EHP) coupled to a central storage tank. The energy performance analysis of the two DHW models is evaluated by dynamic simulations under different scenarios (for case two) of charging the decentralized storage tanks by circulating pump units. The results allow an evaluation of the DHW consumption profile, temperature variation in both the system’s central storage and (for case two) decentralized tanks and the annual electrical/thermal energy analysis.