Desiccant cooling systems, considered one of the sustainable air conditioning technologies, have been attractive for researchers to be studied for many years. In this paper, the modeling and simulation of a packed tower liquid dehumidifier and regenerator as well as a solid desiccant wheel are presented. The simplified equations that predict the air conditions after passing these systems are developed. This approach is quick and does not need a lengthy computer calculation and large memory capacity. Liquid and solid desiccant cooling cycles are presented and using this approach, the performance of these systems Is calculated for weather data of a reference year and different climates in the United States. These systems are compared regarding their energy and water consumption based on this new approach. The first results show that liquid desiccant systems, without technology improvements, have the large sizes at lower capacities and have lower coefficients of performance than solid desiccant cooling systems.