The combined influence of thermal and acoustic environment on overall comfort and Productivity in naturally ventilated university classrooms in India

Ceiling fans are commonly used in naturally ventilated classrooms in warm and humid climates to ensure thermal comfort. However, using ceiling fans at higher speeds increases background noise, interfering with acoustic comfort. Most research on thermal and acoustic comfort in classrooms focused on either thermal or acoustic environments. While most of the research on the combined influence of thermo-acoustic environments conducted in climate chambers, did not reflect ranges of temperature and relative humidity experienced in warm and humid climates. Recent studies by the authors have examined the effects of non-uniform environment created by ceiling fans on thermal and acoustic comfort in lecture halls. Building upon these studies, detailed analyses were carried out of the combined effects of thermal and acoustic environments on overall comfort in real educational settings. The research involved on-site measurements of indoor thermal and acoustic variables, along with a comprehensive questionnaire survey assessing students’ subjective responses. In total, 828 student responses were collected across 11 lecture halls over four months. Thermal and acoustical comfort data were analysed together using regression analysis. Higher productivity was reported within 27.8–29.8 °C at 56 dBA background noise. Students accepted the environment with background noise up to 59.9 dBA at 28.8 °C, and the acceptable temperature range varied between 26.1 and 31.5 °C at 56 dBA. Overall comfort was inferred up to 33.4 °C at 61 dBA, but this threshold slightly decreased to 32.5 °C when background noise increased to 65 dBA. These findings can be applied to optimize the indoor environment of lecture halls and increase students' productivity.