Thermal comfort in university classrooms in humid subtropical climate: Field study during all seasons

Ensuring students thermal comfort has complex implications involving student performance and energy consumption costs. Existing models may not be suitable for predicting the thermal comfort of university students. This study aimed to compare the thermal comfort responses of university students in air-conditioned and naturally ventilated classrooms located in a humid Brazilian subtropical climate with the analytical and adaptive models. The study was conducted in 28 classrooms of two universities located in a humid subtropical climate in southern Brazil. Environmental variables were measured using a microclimatic station, while personal variables were obtained through student responses in electronic questionnaires between September 2022 and July 2023. In classrooms operating with natural ventilation, the mean thermal neutrality temperatures were 19.8 °C and 21.4 °C in Joinville and São José, respectively. When operating with air-conditioning, the mean thermal neutrality temperatures were 21.8 °C and 22.1 °C in Joinville and São José, respectively. Even when they answered “neutral” on the thermal sensation questionnaire, students reported that they preferred the cooler environment. Classroom occupant densities less than 1.00 did not influence the students’ thermal sensation. In general, the PMV/PPD model was not able to predict the thermal comfort of university students. The adaptive comfort model proved adequate to predict the thermal comfort of students when classrooms were naturally ventilated.