The application and performance of ground source heat pump (GSHP) systems in Jiangsu, China are reported in this study. Fifty cases were selected from different areas including office, residence, and other building types. Half of the selected cases was measured in summer, and the other half was measured in winter. The water temperatures, energy efficiency, energy consumption and thermodynamic perfectibility were analyzed statistically. The ground provided an average water temperature of 25.4 degrees C in summer and 11.7 degrees C in winter. The temperature difference between the inlet and outlet on the ground side in both the seasons was 3.07 degrees C. The statistical average values of coefficient of performance (COP), energy efficiency ratio (EER), and thermodynamic perfectibility n were 4.62, 3.41, and 0.38 in summer and 4.34, 3.22, and 0.49 in winter, respectively. The energy used by heat pumps and water pumps was about 3:1 in both the seasons. Furthermore, a comprehensive evaluation was conducted based on the statistical baseline set by the collected data. This method included factors that influence the actual system performance and provided an approach to assess and compare the performance of the cases comprehensively. (C) 2017 Elsevier B.V. All rights reserved.