Defining IEQ Comfort Limits for Naturally Ventilated School Classrooms in a Warm-Humid Climate

Abstract The indoor environment quality (IEQ) of classrooms significantly impacts the teaching and learning performance of students and, in turn, can affect their academic achievement. Although national and international standards, such as NBC 2016, ISHRAE, and ASHRAE, specify the comfort limits of the IEQ parameters, studies have found that students were not satisfied with the indoor environment in spite of these specifications being met. This study empirically validates that the comfort limits for IEQ parameters in naturally ventilated school classrooms in a warm-humid climate are contextually different from the generic recommendations made in Standards, and aims to define these limits. Accordingly, fourteen classrooms in four schools in India were studied using qualitative and quantitative methods. In total, 45 spot instrument measurements along with 1,087 questionnaire survey responses were collected from April 2023 to January 2024 across summer and winter periods. It was found that, on average, students were not satisfied with the thermal environment, were satisfied with the visual environment, and were neutral toward the acoustic environment. However, they could not perceive the air quality. Upon correlation of the instrument data with the questionnaire survey responses, it was found that the derived comfort limits for this context were significantly different from the general recommendations for educational buildings in national and international standards, as was hypothesized. Therefore, the derived contextually appropriate IEQ comfort limits can support building engineers and architects in optimizing the design of school classrooms to improve IEQ and, in turn, enhance occupant comfort for effective learning.