In this study, we explore the correlations between indoor climate change and human thermal adaptation, especially with regard to the timescale and weighting factors of physiological adaptation. A comparative experiment was conducted in China where wintertime indoor climate in the southern region (devoid of space heating) is much colder than in the northern region (with pervasive district heating). Four subject groups with different indoor thermal experiences participated in this climate chamber experiment. The results indicate that previous indoor thermal exposure is an important contributor to occupants’ physiological adaptation. More specifically, subjects acclimated to neutral‐warm indoors tended to have stronger physiological responses and felt more uncomfortable in moderate cold exposures than those adapted to the cold. As for the driving force of thermal adaptation, physiological acclimation is an important aspect among all the supposed adaptive layers. However, the physiological adaptation speed lags behind changes in the overall subjective perception.