Library air-cooled centrifugal chillers (2 alternating in 24-hour continuous operation) are installed on the roof of the Macronix Building, providing cooling for 10 small air handling units in the escalator areas on the 5th and 6th floors, the Special Collections Room on the 3rd floor, the Information Room on the 2nd floor, and the Low-Voltage Room in the basement. These chillers have been in operation since their installation in September 2010, making them 13 years old. Due to their outdoor placement without weatherproof casing, the overall framework, copper pipes, and components have severely corroded, posing safety concerns and reducing their Energy Efficiency Ratio (EER), leading to high energy consumption. Moreover, these chillers use R-22 refrigerant, a chlorofluorocarbon (CFC) that depletes the ozone layer (ODP). According to an announcement by the Environmental Protection Administration, the use of CFCs in refrigerant refills has been banned since January 1, 2021. Additionally, the international Montreal Protocol mandates that developed countries completely phase out the use of CFC refrigerants by 2030. Due to the increasing maintenance costs of the air-cooled centrifugal chillers and the reasons mentioned above, a replacement assessment has been conducted since July 2023, with the replacement expected to be completed by 2024.