A study into the effect of indoor air temperature on the thermal comfort, health and performance of users in selected naturally ventilated schools in Nigeria.

Abstract

This study investigated the effect of the indoor air temperature in the classrooms of 11 schools in Minna, Nigeria on: (1) the thermal comfort, health and academic performance of a sample of pupils (2) the thermal comfort and productivity of a sample of teachers. The study involved key literature review into: (a) the contributions of some design features to the indoor air temperature of school buildings (b) the relationship between indoor air temperature, thermal comfort, health and academic performances. Following the literature review, a series of field experiments were conducted in which the thermal comfort, health and academic performance of the pupils from the schools were evaluated at mean air temperature of 25.60C and 34.50C between November-December 2016.Similarly, field surveys of the 11 schools were carried out between March-April 2017 where the thermal comfort and perceived productivity of teachers (respondents) were evaluated at mean air temperatures of 27.70C and 360C. Furthermore, physical surveys of the design features of the classrooms were carried out. The data from the field experiments were analysed using t-test and Wilcoxon signed rank test, these tests were used to compare the thermal comfort, health and academic performance of the samples at indoor air temperatures of 25.60C and 34.50C. Results of the t-tests and Wilcoxon signed rank test showed that in comparison to the air of temperature of 25.60C, the air temperature of 34.50C significantly affected the thermal comfort, health and academic performance of the samples (pupils) in the mathematics based test .In contrast, there was no significant effect observed in the English language based test. As well, using the data from the field surveys, the study compared the thermal comfort and productivity of teachers (respondents) at 27.70C and 360C. The results showed that; in comparison to the air temperature of 27.70C, the air temperature of 360C significantly affected the thermal comfort and perceived productivity of the respondents. A descriptive analysis of the data collected from the physical surveys of classrooms suggest that the design features of the classrooms have the propensity of contributing to heat gain and elevated air temperatures indoors. Further analysis of the data from the physical surveys through simulations of the annual thermal performance using IESVE software showed that; the naturally ventilated classrooms procured for public schools in Minna cannot moderate the air temperatures all year round to fall within the standards suggested in previous research for promoting thermal comfort and performances indoors. Overall, the findings from this study suggests that relatively high indoor air temperatures can have negative effect on the thermal comfort, health and performance of users of school buildings even if the users are presumed to be acclimatised to the tropical climate of Nigeria. Furthermore, the findings from this study provides evidence based data that may be used to promote best practices, policies and funding in the provision of public schools in Nigeria for the sake of the wellbeing and performance of teachers and pupils. Also, the findings from this study which was conducted in a natural setting of a tropical climate strengthens previous research concerning the link between indoor air temperature and performance which were mostly conducted in temperate climates and climatic chambers. Lastly, based on the findings from this study, recommendations that aims to promote thermal comfort and performance in classrooms of public schools in Nigeria were suggested.