Thermal history and adaptation: Does a long-term indoor thermal exposure impact human thermal adaptability?

Harbin is located in China's severe cold area with a long and cold winter. Currently, some buildings are overheated in winter, which not only waste energy, but also may weaken human adaptability to the cold climate. A long-term field tracking study was carried out from 2013 to 2015 covering two space heating periods in Harbin. Two types of residential heating environments, respectively warm exposure and cool exposure environments were investigated to discover relation between different indoor heating temperatures and human thermal responses. Totally, 36 residents volunteered as participants. The subjective survey and environmental parameters monitoring were simultaneously conducted. The results show that all participants could adapt to their thermal environments well. But the participants' thermal adaptation was evidently discrepant in different exposures. The neutral temperature was 1.9 °C higher in warm exposure than cool exposure sample after clothing insulation standardization, which suggests the possible effects of physiological and psychological adaptation. The discrepancy between AMV and PMV was greater in cool versus warm exposure. The results indicate that a higher thermal comfort zone might be formed for the residents exposing to a high indoor heating temperature for a long period in winter. Furthermore, a broader acceptable temperature range was presented in this climate area than ASHRAE steady-state comfort zone in winter. These findings have far-reaching implication for reasonable energy use.