1 Eco-friendly Cooling System Design for a Hostel Building Nikhil Malviya*, Prashant Akhilesh Tiwari*, Dilawar Husain*, Ravi Prakash* 1 Affiliation: *Motilal Nehru National Institute of Technology, Allahabad, Prayagraj,(UP) India 1 Email: rprakash234@gmail.com Mobile: +91-9336668662 Abstract In order to provide thermal comfort in a tropical country like India, the use of conventional window air-conditioners is very much electricity intensive, which may lead to a further increase in the greenhouse gas (GHG) emissions. A significant economic and environmental advantage can be achieved by adopting modified air cooling systems. This paper presents a case study for proposing a design of an energy-efficient and affordable cooling system for a hostel building located at the Motilal Nehru National Institute of Technology, Allahabad located at Prayagraj (UP), India. The design consists of a solar electricity-based centralized chilled water air conditioning system and an earth air heat exchanger (EAHE) as a passive cooling solution. The EAHE takes advantage of the fact that at a depth of 4 meters, the earth’s temperature remains constant throughout the year. An earth air tunnel can provide year round thermal comfort i.e. both heating and cooling depending on inlet air temperature. Simulation showed that, when air is blown at 6.2 m/s velocity through a 70 meter long EAHE with 0.5 meter diameter, the temperature changes from 45°C to 26°C in summers and from 4°C to 16°C in winters. The chilled water AC system is designed for operation with a smart solar grid electricity connection. Results obtained for the solar driven AC system showed that, for a building with 328 TR cooling load, only 65 tCO2 emission are produced annually, which would have been 928 tCO2 if connected through grid electricity. This reflects 93% potential reduction in GHG emissions. Keywords: Sustainable Systems, Energy Efficient Design, Earth Air Heat Exchanger, Thermal Comfort, Renewable System. 1. Introduction Global warming and urban heat island increase the demand of thermal comfort inside the built envelope. The most common solution is to use mechanical air-conditioning (AC) systems. But for the large cooling requirement (such as in hostels, hospitals, theatres etc.), this solution proves to be very energy intensive.