Field experiment on transient thermal comfort in a Chinese railway station – High temperature exposures

Thermal alliesthesia describes the phenomenon where the perception of a given environmental thermal stimulus can be either pleasant or unpleasant, depending on the individual's internal thermal state relative to homeostasis. Quantifying the thermal alliesthesia effect in human thermal perception of periodic transient metabolic rates and thermal environmental exposures can potentially enhance the thermal experience of temporarily occupied built environments, such as a railway station. A field experiment was conducted in a railway station in southern China during hot and humid summer months. Sixteen college-age participants were recruited to undergo simulations of entering the railway station after having been exposed to various intensities of heat, and then sitting quietly in the station waiting hall. Thermal environmental parameters, thermal physiological parameters, and subjective perceptions of participants were registered throughout each field experiment. The results indicate that the effect of prior heat exposures on skin temperatures and subjective perceptions were extinguished within 10 min after participants entered the station. Step-changes from low-to-high intensity activity induced a more immediate and pronounced change in metabolic heat production, compared to the reverse scenario. A transient thermal perception model is proposed with the input parameters including the environmental temperature and metabolic rate transients, inter alia. The algorithm in the model indicates that thermal alliesthesia induced by temperature step-change within transition spaces could be negligible, whereas metabolic transients exert a more decisive influence. The study provides insight into the alliesthesia experienced in transitional spaces and guidance for designs and operations of HVAC systems. • Conducting a field experiment on transient thermal comfort in a railway station. • Analyzing effects by periodic transient environments and activity shift on human. • Modeling transient thermal comfort to environmental step change and activity shift. • Suggesting measures for HVAC system to accommodate thermal alliesthesia.