Análise das condições de conforto térmico e a influência da renovação de ar em salas de aula de estudantes universitários

Abstract

Although many times the climate conditions are appropriate to achieve thermal comfort in buildings that operate with natural ventilation, the number of buildings that apply mechanical cooling, for example the air conditioning, as main climatization strategy have increased considerably. Besides problems in consequence to the elevated energy consumption, some studies show that this situation can provide a bad indoor air quality (IAQ), which in case of teaching environments can be seriously harmful. On the other hand, the use of mechanical ventilation can generate a significant effect at inside cooling with lower energy consumption and with better air renewal rate. Therefore, this study aims to analyze the influence of air renewal at university students’ thermal comfort, comparing results of field measurements and subjective searches in classrooms with natural ventilation and a classroom with mechanical ventilation system. The field experiments were carried out in classrooms on the campus of the Universidade do Vale do Rio dos Sinos (Unisinos) in São Leopoldo city, with emphasis at the warmest season of the year. The data were collected from environmental measurements carried out concomitantly with subjective surveys, which were performed through a questionnaire delivered to the students, occupants of the evaluated environments, resulting in a total of 616 questionnaires. The analysis was carried out from the obtained information, and the results presented in the form of graphs and tables, through the crossing between the microclimatic data and the users' answers. The results showed that the classroom occupants with mechanical ventilation presented more satisfactory thermal sensation, comparing to users of other evaluated classrooms. In relation to thermal acceptability in comparative days evaluated, 72.5% of the occupants in classroom with greater air renewal classified the environment as "acceptable" and 27.5% as “unacceptable”. For the other classrooms, only 40% of the occupants classified the environment as "acceptable" and 60% as "unacceptable". The study also showed, at the months in warmest season, a better applicability of the adaptive comfort model in the classroom with higher rates of external airflow. The results also show that the increase of the air renewal rate in the proposed classroom, together with the adaptive actions of the occupants, provided better conditions of thermal comfort when compared to the rooms with natural ventilation.