Multi-functional Integrated System for Energy Retrofit of Existing Buildings: A Solution Towards nZEB Standards

The present work is aimed at assessing the energy performances of a multi-functional integrated system designed to cover the HVAC needs using renewable energy sources (RES), with a specific focus on residential buildings. In detail, within the system design, RES are represented by building integrated photovoltaics (BIPV) and aerothermal energy. The heating, cooling and DHW demand is in fact satisfied by a reversible and high efficiency air-water heat pump with continuous power modulation, optimized for the specific purpose, directly fed in direct current (DC) from the PV. The eventual surplus of PV production can be stored in form of thermal energy thanks to a dedicated storage system for providing heating, cooling or DHW production in the periods when there is no/low solar radiation. Moreover, the system is able to minimize the peak power demand of electricity, according to the match between PV electricity generation and usable/storable thermal energy demand. The results of the energy simulations on a case study residential building demonstrate the effectiveness of the proposed system towards nZEB standards.