Thermal Comfort Analysis in Both Naturally Ventilated and Air-Conditioned Classrooms in a Warm and Humid Climate

Abstract

Thermal discomfort in schools can compromise students and teachers well being and health; in addition, many cognitive processes are influenced by thermal environment. One solution to avoid thermal discomfort in a tropical climate can be the installation of air conditioning devices. However, little do we know about the thermal comfort in air-conditioned school buildings, specially considering the particularities of a tropical climate. This study aims to analyse the perception and sensation of thermal comfort in school buildings. Naturally ventilated and air-conditioned classrooms of public schools in João Pessoa, northeast Brazil, were investigated. A number of 352 children, aged 8 to 11 years old, were interviewed. The research’s methodology consisted in measuring environmental variables (air temperature, mean radiant temperature, relative humidity, air velocity), while questionnaires were applied to the children, containing four questions regarding their sensation and preference towards the thermal environment. In the naturally ventilated rooms, we observed the average air temperature of 28,78 °C, with 45,53% of the children feeling discomforted by heat, and 22,77% of them discomforted by cold, also 47,97% of the children reported a preference for a colder room and 24,39% reported a preference for a warmer room. In the air-conditioned rooms, we observed the average air temperature of 26,99 °C, with 39,37% of the children discomforted by heat, and 25,57% of them discomforted by cold, also 55,68% of the children reported a preference for a colder room and 14,46% reported a preference for a warmer room. The study emphasizes the occurrence of different votes of thermal sensation at the same air temperature range. The results also showed divergence between PMV and children real votes in air-conditioned rooms, encouraging the questioning about the indiscriminate use of air condition systems.