Multi-Objective and Multi-Criteria Optimization of Microgrids for Nearly Zero-Energy Buildings

Nearly zero-energy buildings (NZEBs) are high energy performance buildings in which part of the amount of energy that these buildings require comes mostly from renewable sources. In order to obtain the target of nearly zero energy consumption, the electrical loads and the energy sources related to the NZEB building can be organized as a Microgrid, which needs to be optimally sized in his components. The optimal sizing of a Microgrid for NZEBs can be formulated as multi-objective problem. In fact, for the NZEB owner exists an economic target aimed at maximizing profits from microgeneration, a different one aimed solely to minimize the energy bought from the market and an environmental target aimed at minimizing the global CO2 emissions. These objectives can enter into conflict and create the need for combined optimization. In this paper, this optimization problem is investigated with an integrated framework addressing the multi-objective optimization and multi-criteria evaluation issues simultaneously. Minimize the investment cost, maximize the fraction of energy self-consumed with renewable energy sources and reduce the CO2 emissions will be considered as three objectives for multi-objective optimization. The proposed methodology is applied to a microgrid for a NZEB public building. The simulation results show the effectiveness of the proposed methodology.