Field study on indoor thermal comfort of office buildings using evaporative cooling in the composite climate of India

Abstract Thermal adaptation can play a significant role in defining thermal comfort levels for evaporatively cooled office buildings commonly found in India. However, there are no dedicated studies to record the occupant perception and indoor thermal comfort in these buildings. The contribution of adaptive thermal comfort theory on occupant perception remains unclear for accurate design and operation of evaporatively cooled office buildings in India. Therefore, a multi-year field study of thermal comfort was conducted in ten office buildings operated under evaporative cooling systems in the composite climate of Jaipur, India. Transverse type questionnaire following Class II measurement protocols was carried out for recording office occupant's sensation and preferences for different indoor variables using ASHRAE 55 seven point and five-point scales, respectively. A total of 1554 datasets were collected spread over a total period of eighteen months, covering the entire summer season which includes very hot and dry days as well as few rainy days. Comfort temperature calculated using the Griffiths method was found 28.8°C (SD=±1.9°C). Results from the field study showed acceptable indoor humidity and airspeed range of 35-85% and 0.75-1.5 m/s for office subjects. Furthermore, 80% and 90% acceptability limits based on operative temperature and SET* were determined for present field surveys and results were compared with the existing adaptive models in National Building Code of India for different building types. This work is the first step towards the formation of an adaptive comfort model for evaporatively cooled buildings in the composite climate of India.