Creat. Sp.

Perceived Thermal Environment of Naturally- Ventilated Classrooms in India

Ramprasad Vittal and Subbaiyan Gnanasambandam


Thermal environment, Adaptive thermal comfort, Classrooms, Adaptive opportunities, Field Study.

PUBLISHER The Author(s) 2015. This article is published with open access at

Higher education institutions are expected to provide high-quality education, which demands learning environments that have well-integrated information and communication technologies (ICT). Contemporary trends in pedagogy focus on, among other things, learner-centred environments. Institutions that are keen to promote ICT-enhanced education and to facilitate blended learning, wherein e-learning practices are integrated with traditional classrooms practices, face infrastructure challenges. There is a considerable and growing literature on the thermal environment of classrooms in several other countries [14,20,22,28,32,36,37]. However, field studies of thermal environment of classrooms in institutes of higher education in India are rarely reported in literature. A few field studies were recently conducted on thermal comfort in naturally ventilated laboratories and classrooms in Kharagpur, India, by Mishra & Ramgopal [24-27]. An earlier study in India by Pelligrnio et alinvestigated thermal comfort in classrooms in two universities in Kolkata[31].

Institutions that are in the process of upgrading and refurbishing naturally ventilated classrooms to meet the current and future pedagogy requirements consider providing air-conditioned environments, which has potentially serious implications for energy consumption. Considering the energy scenario in India, such decisions need to be revisited. There are increasing numbers of higher education establishments in both the public and private sectors. This phenomenal growth, coupled with increased number of air-conditioned learning spaces can adversely affect energy demand. During power-cuts, the diesel generators often installed in higher educational institutions in India are incapable of operating the air conditioners.

To reduce the energy consumption of educational buildings, it will be appropriate to use adaptive thermal comfort standards during the design phase. Currently in India, there are no such adaptive thermal comfort standards. This calls for increased number of field studies in various types of buildings, including educational buildings in different climatic zones of the country, so as to arrive at such standards. Apart from the serious energy implications, what does the indoor environmental quality mean to students, who are the primary or key stakeholders in such institutions? How do students perceive the thermal environment of their classrooms? There is a strong need to study such perceptions. The present study, therefore, investigates how architecture students at an institute of national importance in India perceive their classroom thermal environment.

In the context of air-conditioned spaces, the National Building Code (NBC) of India 2005[3] specifies conditions for classrooms during summer months as: 23–26 °C, with 50–60% relative humidity, and 23–24 °C with not less than 40% relative humidity during winter. The relevance of these specifications was questioned by Indraganti and Rao [15] and Pellegrino et al.[31]. For naturally ventilated spaces, the NBC specifies Tropical Summer Index within the range 25.0–30.0°C as comfortable (optimum 27.5 °C). However, the code does not refer to adaptive thermal comfort. The objective of this study was to assess students’ perceptions of thermal environment, in terms of thermal sensation, satisfaction with classroom temperature; freedom to open or close window shutters, and to control the speed or switch on/off ceiling fans; the acceptability of: temperature and air movement and, thermal / air movement preferences


A field study of thermal environment in naturally ventilated classrooms was conducted in the Department of Architecture at the National Institute of Technology, Tiruchirappalli, India. The study included 176 architecture students and was conducted over five days during the comparatively cool months of December and January. The results show that 82% of participants voted for ‘comfortable’ on the thermal sensation scale. Cross tabulation of thermal sensation and thermal preference shows that 50% of those who voted within the ‘neutral’ thermal sensation range preferred cooler temperatures and 43% wanted no change. Classroom temperature was acceptable to 85% of students and unacceptable to 15% of students. Perceived thermal sensation tends toward the cool side (mean -0.26). Regression analysis yielded a comfort zone (voting within -1 and +1) of 26.9–30.8 °C, with neutral temperature of 29.0 °C. Standard adaptive comfort models yielded lower temperature than field findings.

Page(s) 149–165
ISSN Print : 2321-3892, Online : 2321-7154
DOI 10.15415/cs.2016.32010

The subjects of this study are the students of architecture who are aware of the issues regarding the various dimensions of the indoor environment, including thermal comfort. TSI indicates thermal sensation as “comfortable” and this complies with the specifications in the National Building Code of India 2005. A skew toward the cool side is observed in TSV and the mean thermal sensation was -0.26. Standard adaptive comfort models yield lower temperature than field findings, indicating that the students are well adapted and tolerant of a wide range of temperatures. Further field studies are needed in various types of buildings and in different climatic zones of the country in order to develop an adaptive thermal comfort standard relevant for India.

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