Thermal comfort assessment and characteristics of occupant's behaviour in naturally ventilated buildings in composite climate of India

Abstract

Energy consumption in Indian building sector is increasing at high rate. The National Building Code of India specifies a narrow comfort temperature range between 21°C and 26°C for all types of buildings and for all seasons. A thermal comfort field study was conducted in 32 naturally ventilated buildings, collecting a total of 2610 samples spread over a total period of four years, covering multiple seasons, age groups, clothing types and building types. Questionnaires were administered to building occupants to record sensations and preferences for air temperature, relative humidity and air velocity on ASHRAE seven point and five point scales. The objective of the study was to evaluate thermal comfort of occupants and study the methods of thermal adaptation such as adjusting clothing, window opening, and use of air circulation fans. Griffith's method was used to determine thermal neutrality. The comfort temperature for summer and winter season was found to be 30.6°C and 25.2°C, respectively. Preferred clothing level for summer was found to be 0.30clo, whereas in winter it was 0.80clo. Preferred air velocity was observed as 0.62m/s in summer season and 0.27m/s in winter. Controlling air velocity has been found to be preferred method of thermal adaptation over adjusting clothing and window opening.