Energy consumption by buildings is rising rapidly due to an increase in population and living standards. Approximately 71% of global energy consumption is due to infrastructure, commercial and residential buildings. In order to provide thermal comfort in a tropical country like India, the use of conventional window air-conditioners is very electricity-intensive, which may lead to a further increase in greenhouse gas (ghg) emissions. This study considers a hostel building of an engineering institute located in the tropical city of Prayagraj, UP, India. The cooling load estimation is done considering location, orientation, size, capacity (occupants), and design of the rooms of the building. An energy balance model is developed to calculate the heat gain through walls, roofs, and windows. Internal heat gain and infiltration load are calculated by using a standard table and handbook. Monthly averaged solar radiation received by the roof, walls, and windows of the building is also considered in the cooling load calculation. The maximum and the minimum cooling load of respectively 320 ton(3947848.2 Btu/h) and 89 ton(1068000.4 Btu/h) were estimated during May and march month. The estimated load of the selected hostel building is validated with eQUEST software model. Further, a solar parabolic trough collector (PTC) is modeled to heat the heat transfer fluid(HTF), water is considered as HTF. Hot water from the PTC outlet is stored in a storage tank and used the same as a heat source for the generator of the absorption cooling system (ACS) during summer and hot water demand during winter. Monthly averaged solar radiation data of the given location is considered to power the PTC modeling. Maximum and minimum temperatures of water 90 -115C(194-239F)were found. Some important results of the thermodynamic modeling of ACS to meet the monthly cooling demand were also reported.