Optimal chiller loading by improved parallel particle swarm optimization algorithm for reducing energy consumption

•An IPPSO algorithm of optimal chiller loading (OCL) problem is proposed.•The chaotic sequence mechanism, new immigration operator, and nonlinear decreasing inertia weight are developed to improve the performance of IPPSO algorithm.•Detailed experiments are conducted for the parameter settings of IPPSO algorithm.•Experimental results show that IPPSO algorithm can be effectively applied to OCL problem.