Comparative studies on using RSM and TOPSIS methods to optimize residential air conditioning systems

Highlights: • Energy consumption (Q_c) and thermal comfort (PMV) of a TAC system were evaluated. • The optimization aim was to achieve thermally comfort at lowest energy consumption. • RSM and TOPSIS methods were applied for operating optimization of the TAC system. • RSM method used 9 cases saving 74% of computation cost compared to TOPSIS. The operating parameters of task/ambient air conditioning (TAC) systems including supply air temperature (t_s) and air flow rate (Q_s) were reported to have critical effects on energy savings and thermally comfortable environment. Due to the existing contradictions between these two aspects, a multi-objective study should be carried out to realize consuming minimum energy and at the same time to guarantee the thermal comfort level at suitable range. Two optimization methods were adopted in this study, one is the response surface methodology (RSM), and the other is the technique for order preferences by similarity to an ideal solution (TOPSIS) method. The objective of this study was to compare the pros and cons of these two methods. It was found that the optimum operating parameters obtained using RSM method were 26 °C (t_s) and 28.94 l/s (Q_s), corresponding to energy consumption (Q_c) of 46.89 W and PMV of 0.11; while that obtained using TOPSIS method were 26 °C (t_s) and 30 l/s (Q_s), corresponding to energy consumption (Q_c) of 49.64 W and PMV of 0.09. Furthermore, compared with TOPSIS method, there were only 9 cases used in RSM method saving 74% of computation cost.