Thermal Sensation of Tropically Acclimatized Subjects under Fixed Air Flow of Personalized Ventilation

Thermal sensation of tropically acclimatized subjects performing sedentary tasks under personalized ventilation (PV) was explored in this study. The study was conducted in an Indoor Air Quality (IAQ) chamber, which is capable of simulating typical office conditions in Singapore. An experimental design involving interventions in indoor ambient temperature, PV supply temperature and PV supply airflow rate, introduced blind to subjects, was conducted. The indoor ambient temperatures were kept at 23 C or 26 C; PV air supply temperatures were controlled at 20, 23 C or 26 C; and the PV air flow rate at 4.5, 7.3 or 11.2 L/s/person. Eighteen subjects took part in the experiment, assuming seated positions in front of computers and engaged in typical office work, in which PV air was directed at their faces, and they registered their thermal sensation vote at regular time intervals over a 2 and a half hour period. The results showed that during long time exposure of 2.5 hours, thermal sensation of the subjects gradually decreased reaching steady state after one hour. Facial thermal sensation was in the range between thermally neutral to cool for all experimental conditions. Both indoor ambient temperature and PV supply airflow rates had strong effects on thermal sensation of subjects.