The production of domestic hot water plays a very important role in the energy consumption of buildings, with a very significant incidence for buildings with low energy consumption. In the case of existing buildings with a centralized DHW production plant, distribution losses can even exceed 50% of the total thermal energy produced in the thermal plant. Hence the need to find new efficient solutions that can also exploit renewable energy sources. This article presents an innovative system, proposed as part of the e-SAFE project funded under the H2020 Programme. The architecture of the system provides a first level of centralized storage, powered by a heat pump managed in such a way as to optimize the use of renewable energy from PV, from which an alternative service distribution line departs for heating and charging of decentralized apartment tanks for DHW production. The energy results, carried out with dynamic simulation code TRNSYS for a building of 10 apartments with different DHW consumption profiles, highlight the possible advantages of the system in terms of primary energy consumption and comfort temperatures during the day.