SUBJECTIVE AND MEASURED THERMAL COMFORT IN ITALIAN UNIVERSITY CLASSROOMS IN HEATED AND FREE RUNNING CONDITIONS

This work examines the applicability of comfort criteria, based on a heat balance model and on anadaptive model, in naturally ventilated classrooms. The adaptive opportunity of students are limitedduring the lesson time, while they are free during the lesson breaks. The field study was conducted byphysical observations, survey questionnaires and behavioral observations. Both field measurementsand subjective surveys were performed at the same time during the regular lesson period. Thermalenvironment parameters were measured: indoor air temperature, mean radiant temperature, airrelative humidity, air velocity and outdoor air temperature. Through these data, Fangers comfortindices were calculated (predicted mean vote and predicted percentage of dissatisfied people), theactual people clothing and metabolic rate being known; furthermore the indoor operative comforttemperatures were obtained from the adaptive model. The subjective survey basically investigated thethermal acceptability, the thermal preference and the thermal sensation, asking students to assesstheir comfort on subjective scales. The judgments about the thermal environment were compared withthe results of the field measurements. Moreover, the subjective mean votes were compared with thethermal environment perceptions in terms of acceptability and preference. The monitoring campaignwas repeated during two different periods: heating season, with operating heating system and limitednatural ventilation and warm period, in free running conditions: the responses from these two differentconfigurations were analysed and compared. The results relative to the warm period confirm the trendoutlined by the study relative to the heating season, but with a minor intensity, suggesting a correlationbetween the thermal acceptability and preference and the outdoor temperature. In general, thermalenvironments that are judged neutral or slightly warm are accepted and thermal environments that arejudged slightly warm might be preferred.