Optimization of solar energy exploitation for a neighborhood towards nearly zero energy buildings

The energy transition of neighborhoods towards nearly zero energy buildings (nZEBs) is fundamental to promote sustainability. The study deals with this issue by proposing a methodology to optimize energy retrofit through the exploitation of solar energy by photovoltaics. Part of a neighborhood in the city of Naples (South Italy) is investigated. The coupling between EnergyPlus and MATLAB® is used for energy modelling, simulations and retrofit optimization through a smart research method, performing a comprehensive analysis of heating, cooling and electric loads. A Pareto multi-objective approach is applied to minimize both energy consumption and global cost in order to optimize the solar energy exploitation and to achieve the nZEB standard while ensuring cost-effectiveness. Different retrofit scenarios for building envelopes and energy systems are investigated. Two optimal retrofit solutions are identified. One pursues the minimization of the neighborhood's energy impact ensuring a PEC reduction from 116.8 kWh/m2a to 66.3 kWh/m2a with discounted payback (DPB) of around 10 years. The other solution maximizes the cost-effectiveness yielding a PEC around 83.7 kWh/m2a with a DPB of only 4 years. The outcomes offer deep insights into the potentials of energy transition for neighborhoods and guidelines for the implementation of multi-generation energy systems as well as to address public energy policies.