Thermal sensation responses to sudden temperature changes in severe cold regions: A cross-sectional and longitudinal field study

During winter in severe cold regions, people experience transient thermal environment changes when entering and exiting buildings, often involving temperature differences exceeding 40 °C, which can seriously impair human health. This study selected Zhangjiakou, China, a representative severe cold region, as the study area and adopted a combined cross-sectional and longitudinal survey approach to analyze human thermal response characteristics under repeated temperature step changes. The results indicate: (1) The most common thermal sensations were “cool” (24.6 %) and “cold” (24.3 %) in outdoor spaces, “slightly cool” (36.9 %) in transitional spaces, and “neutral” (38.7 %) in indoor spaces. Correspondingly, the predominant thermal comfort votes (TCV) were “uncomfortable” (38.9 %) outdoors, “slightly uncomfortable” (36.9 %) in transitional spaces, and “neutral” (55.1 %) indoors. Air temperature was the most significant microclimatic factor influencing thermal sensation votes (TSV). (2) Exposed body parts were more sensitive to sudden temperature changes, significantly affecting overall thermal perception, whereas core body parts were less sensitive. (3) The neutral standard effective temperature (SET∗) was 17.2 °C in transitional spaces and 19.3 °C in lobby Space (LS). The Neutral SET∗R were 13.6–20.8 °C for transitional spaces (TS) and 15.3–23.3 °C for lobby Space. The acceptable temperature ranges were 6.54 °C-20.16 °C for open Square (OS), 4.78 °C-17.79 °C for transitional spaces, and 16.98 °C-25.80 °C for lobby Space. This study demonstrates that transitional spaces can significantly mitigate the impact of indoor–outdoor temperature step changes on the human body, highlighting the importance of considering transient thermal responses in the design and operation of public buildings in severe cold regions.