For specific applications, efficiencies of both living and non-living beings depend to a great extent on the physical environment. Denon Dct A100 Manual Muscle. The nature keeps conditions in the physical environment in the dynamic state ranging from one extreme to the other. Temperature, humidity, pressure and air motion are some of the important environment variables that at any location keep changing throughout the year. Adaptation to these many a times unpredictable variations is not possible and thus working efficiently is not feasible either for the living beings or the non-living ones. Thus for any specific purpose, control of the environment is essential. Refrigeration and air-conditioning is the subject which deals with the techniques to control the environments of the living and non-living subjects and thus provide them comforts to enable them to perform better and have longer lives. Objectives After studying this unit, you should be able to know what is refrigeration and air-conditioning, know the history of refrigeration, know applications of refrigeration and air-conditioning, and describe the term ton of refrigeration and COP. The Aristocrats Culture Clash Torrent.