The cumulative exergy approach is applied to evaluate two cases with different air conditioning systems. The first case includes three air conditioning systems, one is the gas direct fired air conditioning system, and the other two have air cooled heat-pump chiller and water chiller, respectively; the second case consists of four air conditioning systems, one is the gas direct fired air conditioning system, and the others have centrifugal water chiller, screw water chiller, air cooled water chiller, respectively. The results of the first case show that the air conditioning system with the air cooled heat-pump chiller maybe inferior to t hat with the water chiller, as the cumulative exergy efficiency of the former is 11.28%, which is less than t hat of the latter (11.92%). The second case shows that the gas direct fired air conditioning system, whose cumulative exergy efficiency is 14.86%, is better than the system with the air cooled water chiller, whose cumulative exergy efficiency is only 11.56%. The results are different from those of the exergy analysis, indicating that cumulative exergy analysis is an effective method to quantitatively evaluate different air conditioning systems according to resource utilization. (C) 2010 Elsevier B.V. All rights reserved.