Operation strategy is one of the critical factors that can affect the energy saving, economic, and environmental performance of a combined cooling, heating, and power (CCHP) system. This study models a CCHP system to investigate its annual total cost reduction, primary energy saving, and carbon dioxide emission reduction with respect to a reference system under five different operation strategies as follows: following the electric load (FEL), following the thermal load, following a hybrid electric-thermal load, following the seasonal operation strategy, and following the electric-thermal load of buildings (FLB). All the different operation strategies were optimized considering the part-load conditions for office and residential buildings in Dalian, China. The results indicate that the FLB and FEL yielded better performance than the other strategies. Furthermore, the redundant electricity and heat generated by CCHP systems were analyzed. The CCHP system operating under the strategies that produce less redundant electricity or heat may not yield better performance. However, the CCHP system operating under the strategies that produce huge redundant energy may achieve good integrated performance. (C) 2015 Elsevier B.V. All rights reserved.