Effect of long-term thermal history on physiological acclimatization and prediction of thermal sensation in typical winter conditions

Thermal history plays an important role in thermal comfort of occupants. In this study, climate chamber experiments were conducted in winter using two groups of total 32 subjects who have different indoor thermal histories. The cold-adapted (CA) group consisted of subjects who long lived in naturally ventilated buildings (approximately 11.8 ± 3.4 °C in winter) in the hot summer and cold winter climate zone of China. The warm-adapted (WA) group consisted of subjects who long lived in heated space in winter. Two kinds of thermal conditions were investigated: the temperature dropping (24-16 °C) and constant severe cold (12 °C) conditions. Results show the thermal sensation vote and heart rate of the CA group were significantly different from that of the WA group in a short period when temperature just dropping to 16 °C and in most time of severe cold condition of 12 °C. However, there were no difference in skin temperatures and blood pressure between the CA and WA groups during the whole experiment period in both conditions. Thus, a cold-adapted basal heart rate was proposed to calculate metabolic rate for the CA group. Results show the accuracy of predicted thermal sensation model could be improved while considering the factor of cold acclimatization.