Studies On The Effects Of Physiological Acclimatization On Thermal Responses Of People Accustomed To Different Thermal Indoor Environments

Thermal adaption is an important field of studies on human thermal comfort, as it plays a significant role on helping to understand the effects of the outdoor climate and built environments on human thermal comfort, thus provides guidance for the design of environmental control standards and building energy savings. However, current studies on thermal adaption do not explain clearly such internal mechanisms of thermal adaptation as the relation between physiological acclimatization and thermal comfort. Besides, the current Adaptive Models only link indoor comfort temperatures to outdoor climate and do not consider the effects of building occupants'past indoor thermal histories on thermal comfort, which raises a doubt on its reliability and rationality. The objectives of this paper are to exam the effects of physiological acclimatization on thermal comfort and the effects of past indoor thermal histories on thermal adaption.Research results presented in this paper are as follows:(1) Human thermal response experiments were conducted in a climate chamber to determine if some of the physiological parameters used in existing studies to reflect thermal comfort were sensitive to thermal responses. Some other new physiological parameters were also investigated. Results indicated that skin temperature and heart rate variability (HRV) present close relationships with thermal comfort and could be used in further studies on human thermal response.(2) Climate chamber experiments were conducted on the influence of people's past indoor thermal histories in summer on human thermal response:we tracked the different responses of thermal comfort and physiological indexes to a heat shock of people accustomed to buildings air-conditioned or not in summertime conditions. Results showed that living and working in indoor thermal environments for long periods of time in summer affects people's physiological acclimatization to hot environments-people accustomed to air-conditioned environments have a weaker environments-people accustomed to air-conditioned environments have a weaker capacity to acclimatize to hot environments than those accustomed to non-air-conditioned environments-and that physiological acclimatization to hot environments can significantly affect thermal comfort response to hot environments, but does not affect thermal comfort response to neutral environments.(3) Climate chamber experiments on the influence of people's past indoor thermal histories in winter on human thermal response were conducted:we examined the different responses of thermal comfort and physiological indexes to cold environments between the people accustomed to buildings heated or not in winter. It showed that living and working in indoor thermal environments for long periods of time in winter affects people's thermal adaption to cold environments-people accustomed to heated environments have a weaker capacity to acclimatize to cold environments than those accustomed to non-heated environments - and that physiological acclimatization to cold environments can significantly affect people's thermal comfort response to cold environments.(4) Combining the experimental results above with related theories in the fields of physiology and psychology, the role of physiological acclimatization on thermal adaption, the effects of thermal histories on thermal adaptability were analyzed. It pointed out the fact that physiological acclimatization is an essential factor of thermal adaption, that skin temperature, sweating rate, HRV and HSP70 levels can be used as representative indexes for human thermal adaptability to hot environments and that skin temperature for human thermal adaptability to cold environments. Besides, it revealed that thermal histories are extremely important factors on thermal adaptability: for most people, indoor thermal histories have a more significant influence on human thermal adaptability than outdoor thermal histories. In addition, we proposed a model for the internal relationship between thermal history, the internal mechanisms of thermal adaption and human thermal comfort, in order to improve the conceptual framework of the Adaptive Model.In this paper, experimental data on human thermal response was reported that led to some improvement proposals for the conceptual framework of the adaptive model, they could contribute to a more rational establishment of the adaptive model based on actual experimental data; besides, the important impacts of past indoor thermal histories of building occupants on physiological acclimatization and the significant role played by physiological acclimatization on thermal adaption in built environments were put into light, which could provide theoretical guidance for the design of new building environmental control standards.