It is favorable to increase the energy efficiency of an air-cooled chiller with an efficient, reliable and cost-effective method. Coupling a direct evaporative cooler with an air-cooled condenser seems to be a feasible solution to this problem. To maximize the energy saving potential of an evaporative air-cooled chiller (EACC), which composes of an evaporative air cooler and a conventional air-cooled chiller, a mathematical model was developed and a new index, increase of seasonal energy efficiency ratio (ISEER), was proposed to evaluate the energy saving potential of the evaporative air-cooled chiller. The energy saving potential of EACC was simulated by using the hourly weather data for four typical cities in China. The impacts of various factors on the energy saving potential were analyzed and it was found that there exists an optimal pad thickness which maximizes the energy saving. The optimal pad thickness varies with climatic condition and face velocity. Optimization results of the pad thickness in 31 main cities in China are presented. The maximum energy saving potential of EACC in China is between 2.4% and 14.0% depending on the climatic condition. It is necessary to determine optimal values for the design parameters according to different climatic condition for maximum energy saving. (c) 2013 Elsevier B.V. All rights reserved.