Baba Ramdev's ashram in Hardwar called Patanjali Yogpith is the spiritual destination of large numbers of Indian and foreign devotees. It is 115 m/377 ft wide, 165 m/541 ft long and 13 m/42.6 ft high. While air conditioning the hall would perhaps give to the yoga practitioners physical comfort commensurate with the spiritual bliss they experience there, it would be rather an expensive proposition. But the salubrious climate of the holy city offered an affordable solution. Rather hot and dry in the summer, but moderate in the winter, the climate is ideally suited for evaporative cooling. The authors used 22 evaporative coolers, eleven on each side of the hall. Each cooler is ducted into a plenum in the hall. They achieved 85% efficiency of the coolers by using 20HP motors for each unit. Since they used pre-fabricated structure with hot air trap in the middle, they created a positive pressure of cool air so that hot air rises and is naturally exhausted from louvers placed at the centre and sides of the hall.