Evaluation of thermal environmental conditions and thermal perception at naturally ventilated hostels of undergraduate students in composite climate

• Neutral temperature was obtained 30.15 °C in naturally ventilated student hostels.
• Difference in neutral temperature was found for single, double and triple occupancy.
• Overall comfort was found statistically significant with Thermal and RH sensation.
• To restore comfort, occupants gave first preference to window opening.
• Comfortable temperature has strong relationship with outdoor temperature.

Field study of thermal comfort was conducted in six naturally ventilated hostel buildings of composite climate considering Class-II protocol of field measurement during summer 2011. Total 429 survey samples of same age group (average 19.6 years) were collected including objective and subjective measurements. Statistical analysis of student's responses and measured thermal environment variables was performed to determine existing indoor environmental conditions and priority of using behavioural controls. Thermal comfort indices were also calculated and compared to the student's perceptions.Neutral temperature was found to be 30.15 °C through regression analysis, with an average clothing of 0.41 Clo (min. 0.19 Clo, max 0.82 Clo). Results have shown a wide bandwidth of neutral temperatures (25.9–33.8 °C) for the hostel buildings which is higher than national/international standards of thermal comfort. Acceptable air velocity and relative humidity were found to be 0.51 m/s and 36%, respectively. Analysis has shown that about 51% students felt ‘overall thermal comfortable’ at the existing environmental conditions in the hostel rooms and only 38% occupants were comfortable based on room air temperature. Students from single, double and triple occupancy rooms were found thermally satisfied at neutral temperature of 30.4 °C, 30.1 °C and 29.8 °C, respectively and their thermal preferences were different.