Research on Energy-Saving Retrofit of Office Building Refrigeration Plant in Hot–Humid Region

Frequent extreme weather driven by climate change makes building resilience an essential guarantee for urban livability and sustainable development. As key building energy-consuming facilities, aged refrigeration plants suffer from low efficiency, high energy consumption of fixed-speed pumps, poor cooling tower heat exchange and failed automatic control. This study develops an integrated energy-saving retrofit framework for aged refrigeration plants of office buildings in hot–humid regions. The framework integrates equipment retrofit scheme design, techno-economic trade-off evaluation, on-site implementation, and long-term measurement and verification, and covers full-chain upgrades of chillers, water pumps, cooling towers, metering, and intelligent group control systems. Implemented on an aged refrigeration plant of an office building in Guangzhou, the optimal retrofit scheme improves system-level energy efficiency to top-runner tier, and core equipment including chillers, water pumps and cooling towers achieve satisfactory real-world operating performance after renovation. Efficiency deviations between actual and rated performance of chillers are mostly below 10%; variable-frequency retrofits raise the chilled-water and cooling-water transport factors to above 35 and 45, respectively, and cooling towers deliver performance consistent with their rated values under the local subtropical climate. This integrated retrofit framework provides practical engineering references for retrofits of similar aged refrigeration plants in hot–humid regions.