Seasonal effect of humidity on human comfort in a hot summer/cold winter zone in China

Adaptation to different seasonal climates may affect human subjective responses to humidity. In this study, thermal comfort, humidity comfort and perceived air quality were investigated with subjects exposed in a climate chamber during spring, summer and winter. Sixty subjects were recruited in total, divided into groups of 20 subjects for each season. Temperature was set at three levels (cool, moderate and warm) during experiments in ranges of 20–28°C, 23–32°C, 16–28°C for spring, summer and winter, respectively. Likewise, relative humidity was set at three levels: 15% (low), 50% (moderate) and 85% (high). Results showed that seasonal difference had a significant effect on human subjective responses to humidity. The combined effect of temperature and relative humidity on thermal perception, humidity perception and perceived air quality was closely related to standard effective temperature (SET*), humidity ratio and air enthalpy, respectively. Comfort humidity ranges were 7.9–15.1 g/kg, 3.3–18.8 g/kg and 2.9–12.8 g/kg (humidity ratio) in spring, summer and winter, respectively. Overall, our results indicate that different comfort humidity limits should be considered for different seasons in the hot summer/cold winter zones of China