Evaluation of Seasonal Variations of Human Subjective Responses in China’s Cold Climate Zone

The thermal perception of the human body changes with seasons. The seasonal variation of subjective thermal responses and the separation of thermal sensation and thermal comfort were studied in this paper. A new evaluation index of thermal comfort was proposed. The study was based on field surveys of 32 university students in Jiaozuo city in the cold climate zone of China. Totally, 854 valid datasets were obtained. Results indicated that the environmental parameters, clothing insulation, subjective responses and mean skin temperature were all affected by seasonal variations. The mean skin temperature increased with the rise of indoor air temperature. The influence of season changes on the difference between mean skin temperature and indoor air temperature (T_dif) was obvious. The separation of thermal comfort and thermal sensation was obvious in the four seasons. TSVs deviated 0.76, 1.13, 0.83, and 1.37 units from the thermal neutrality when TCVs were the lowest in the four seasons, respectively. The separations were more obvious in seasons with extreme climates (summer and winter) than in transition seasons with mild climates (spring and autumn). People’s emotion was affected by the thermal environment. The hotness in summer increased “boring” feelings, and the coldness in winter reduced people’s pleasantness. T_dif was proposed as a reflection of human thermoregulation. An optimal T_dif range between 6.0°C and 12.0°C was proposed, in which optimal thermal and emotional conditions were achieved. The study provides a theoretical basis for the seasonal study of human thermal response and the dynamic control of the indoor environment in the future.