Some commonly used applications are process cooling by chilled water or brine, ice plants, cold stores, freeze drying, airconditioning systems etc. Comfort air-conditioning generally implies cooling of room air to about 24 ° C and relative humidity in the range of 50% to 60%. Industrial process air conditioning and precision air conditioning may require temperatures ranging from 18 ° C to 24 ° C with relative humidity Values ranging from 10% to 60%. This manual highlights some issues related to energy efficiency and energy conservation in refrigeration and air conditioning, along with some emerging innovative techniques to eliminate or minimize conventional refrigeration and air conditioning.