Acceptable temperature steps for transitional spaces in the hot-humid area of China

Transitional spaces account for a large proportion of building area and have significant impacts on human thermal comfort. This study conducted an experiment on the effect of temperature steps in transitional spaces on human thermal comfort. Thirty local people from the hot-humid area of China were recruited as subjects and exposed to different steps between a neutral temperature of 26 °C and non-neutral temperatures ranging from 20 to 32 °C in a climate chamber. The subjective and physiological response results show that warm sensation overshoots occurred under sudden heating, with the probability depending on both the step magnitude and the initial temperature, and cold sensation overshoots occurred in the warm-neutral steps. An asymmetric phenomenon was identified as the mean thermal sensation vote in the neutral condition changed significantly before and after steps. The subjective responses were anticipatory as they led changes in skin temperature, and the thermal comfort and acceptability responses were more anticipatory as they led changes in thermal sensation. The relationships between thermal sensation and the skin temperature change rate were identified, indicating that the skin temperature change rate caused a sensation that compensated for the sensation caused by the skin temperature itself. Step magnitudes no larger than 3 °C were proposed as acceptable temperature steps for transitional spaces in the hot-humid area. This study extends the understanding of the temperature step effect and provides valuable references for designing transitional spaces in the hot-humid area.