Water chiller is a crucial air conditioning unit in various industries, tasked with efficiently cooling large spaces. It utilizes two refrigerants, primary and secondary, during its cooling process. A well-functioning air conditioning system not only ensures human comfort but also benefits machinery and the overall environment. However, one significant issue leading to excessive electricity consumption is the mismatch between the refrigeration system's initial design and its real-world operation. To ensure energy efficiency, it's essential to evaluate the chiller's performance meticulously. To analyze the water chiller's performance, data was collected from its control panel over three days. This data includes water pressure and temperature both entering and exiting the evaporator, set point ampere, and compressor power. With this data, the actual Coefficient of Performance (COP) can be calculated and compared against the design COP. The research findings reveal that between January 23, 2023, and January 25, 2023, the chiller's actual COP falls below the design COP at 05:00, 08:00, 11:00, and 21:00. However, at 23:00, the actual COP surpasses the design COP. In conclusion, the water chiller demonstrates less efficient cooling during specific hours, resulting in heightened energy consumption.