The study we present here analyzes the status of the water chiller energy efficiency standard in China. The national standard, GB19577-2004, which sets the grade and scale of water chiller energy efficiency, has been implemented for five years and has produced achievements in energy-saving and emission reduction, which is a basic state policy in China. This paper presents extensive investigations on water chiller energy efficiency conducted in 2009 and compares these results with results from 2003. This analysis shows that the average energy efficiency level in 2009 was higher than in 2003. Moreover, large units with more than a 5000 kW cooling capacity have now appeared, and low efficiency units with EERs (energy efficiency ratios) below 3.8 have been phased out. The standard should be upgraded every five years. Therefore, this paper proposes a draft of a new energy efficiency standard. In the draft, thermodynamic perfectibility eta is presented to be used as an indicator instead of the EER; for eta, 0.4 is the minimum allowable value and 0.6 is the maximum value. There is one category of cooling capacities, from 100 to 2000 kW, in which the energy efficiency has a linear relationship with its cooling capacity. (C) 2010 Elsevier Ltd. All rights reserved.