This paper presented a case study on performance analysis of ground water-source heat pump system (GWHP) for a hotel building retrofit Splitting air-conditioner was used for cooling and coal fired boiler was used for heating in original system. The GWHP system could save electricity energy and water source consumption under improved operation methods compared with the common operation methods. In this study, the experimental average cooling coefficient of performance (COP) of the units and system were 5.53 and 3.29, respectively (from Jun. to Sep.). The average heating COP of the units and system were 4.45 and 2.79, respectively (from Nov. to Feb.). The primary energy consumption of GWHP system was reduced by 42.9% when compare with the original cooling/heating system in a year. The indoor air temperature fluctuated in comfortable range (19.3 degrees C-24.4 degrees C) during test day in winter. The results show that the GWHP system was particularly suitable for this hotel under our improved operation methods. This renewable and environment-friendly technology could promote energy conservation and sustainability obviously for the hotel building. (C) 2015 Elsevier Ltd. All rights reserved.