Summertime Thermal Comfort in Australian School Classrooms

Considering school students spend up to one third of their day inside classrooms, it’s surprising how few detailed empirical studies have been conducted into how the thermal environment of classrooms affects students’ comfort and performance. Whereas PMV tends to exaggerate warm discomfort for adults, the literature suggests it underestimate children’s actual thermal sensation, but there is no coherent explanation for this in terms of metabolic or other physiological differences to date. The aim of this study was to conduct a thermal comfort survey in actual classrooms with a view to empirically defining preferred temperatures, neutral temperatures, and acceptable temperature ranges for Australian school children, and to compare them with findings from adult populations. The study informs a thermal comfort (air conditioning) policy being developed for Australian schools. The survey was conducted in a mixture of Air-Conditioned (AC), Evaporative-Cooled (EC), and Naturally-Ventilated (NV) classrooms in 10 schools during the Austral summer of 2013. Both Primary (grade) school and high schools were included in the sample. The survey was conducted twice a day (morning and afternoon), and the survey period varied between schools, from one week up to three weeks. After quality assurance processing a total of 3,129 questionnaires were retained from the sample of students and 138 samples were from the teachers. An indoor operative temperature of about 22.5°C was found to be the students’ neutral and preferred temperature, which is generally cooler than expected of adults under the same thermal environmental conditions, confirming earlier research findings in the thermal comfort literature. Working on the industry-accepted assumption that an acceptable range of indoor operative temperatures corresponds to mean thermal sensations of -0.5 through +0.5 (ASHRAE 2013; ISO 2005), the present analysis indicates an acceptable summertime range for primary and high school students from about 18.5 through to about 26.5oC operative temperature.   The paper concludes with hypotheses to explain differences between thermal comfort of children and adults.