Cooling waters systems and refrigeration systems are required to provide cold utility to chemical processes. Little attention has been placed on the structure and system interactions between cooling systems and processes. hi this article, an integrated design and retrofit method for cooling systems is reviewed. cooling water system design, a new design methodology has been developed for debottlenecking of cooling water systems. Reuse of cooling water between different cooling ditties enables cooling water networks to be designed with series arrangements. This allows better cooling tower performance and increased cooling tower capacity. The interactions between the performance of the cooling tower and the design of cooling water networks are explored systematically. For refrigeration system design, a systematic design and retrofit method has been proposed for refrigeration systems using pure or mixed refrigerants. A graphical exergy analysis method, the Omega-H diagram, is introduced to help engineers obtain understanding and insights into complex refrigeration systems. The systematic synthesis method proposed in this article can greatly improve operating efficiency for refrigerant systems.