Study on personal comfort heating system and human thermal comfort in extremely low-temperature building environments

Exposure to extremely low-temperature building environments around -20 °C causes various hazards to human health. However, few studies have studied human thermal comfort and physiological response in such environments, nor the personal comfort heating system. Thus, this study investigated the heating characteristics of personal comfort heating system, their effects on thermal responses, and thermophysiological parameters in extremely low-temperature building environments. We conducted experimental tests and questionnaires in a cryogenic enthalpy difference laboratory with air temperature ranging from -21.2 to -15.6 °C and a relative humidity of 55 %. Eight experimental conditions were designed with several heating measures (heating mat, heating gloves, heating cushion and airwarmer). The heating parameters of the personal comfort heating systems as well as the subjective evaluations and skin temperature of the subjects were recorded and analyzed. The results showed that the airwarmer confinement box condition had a corrective power of up to 38.3 K. The overall thermal sensation vote and overall thermal comfort vote were maintained at 0.25 and -0.25. Further, we found that the face, hands, calves and feet got cold easier with the largest skin temperature difference of -4.9, -8.1, -6.7 and -7.6 °C, respectively. Besides, the relationships between thermal responses and between thermal responses and skin temperature were examined, as well as a thermal comfort assessment methodology was established for extremely low-temperature environments.