Study Of Human Thermal Comfort And Respiratory Immunity In Thermal Environments With Temperature Drift

With the strict requirements for indoor environment,dynamic thermal comfort and human health in the indoor environment are gradually gaining attention.Frequent access to airconditioned environments can lead to human comfort and health problems.Solutions to such problems have been provided by studying thermal comfort changes under temperature steps.However,the psychological and physiological discomfort of human beings caused by long-term indoor air-conditioning environment still needs to be urgently addressed.A dynamic thermal environment with temperature drift can be a good solution to the above problems.Appropriate hot and cold stimulation by temperature drift can improve the body’s thermal adaptation ability as well as thermal regulation.Moreover,temperature stimulation affects the heat and moisture exchange between the human respiratory system and the surrounding environment,resulting in the immune response of the respiratory tract being affected.Respiratory immunoglobulin E(IgE),one of the antibody proteins secreted by the mucous membranes of the respiratory tract,has the ability to defend against pathogens.IgE was selected as an indicator to characterize respiratory system immunity in healthy populations.This provides a new idea for the study of human respiratory system immune health under dynamic thermal comfort.By briefly shutting down the indoor air-conditioners in winter and summer,this paper creates a change in temperature drift down(natural decrease in temperature)and temperature drift up(natural increase in temperature)in winter and summer,respectively.The initial stabilization temperature of 18℃/24℃ was selected for the winter experiment.The initial stabilization temperature of 22℃/25℃/28℃ was selected for the summer experiment.Data of physiological indicators such as subjective thermal voting,skin and core temperature,and heart rate variability were collected from 16 postgraduate students.And the salivary IgE concentration of subjects were examined.This study first analyzed the changes in subjective evaluations and objective physiological parameters of subjects in winter and summer temperature drift environments.It was found that temperature drift could improve human thermal comfort and thermal adaptation ability in the cold-leaning environment of winter and the warm-leaning environment of summer.Appropriate temperature drift can be used to reduce the indoor air conditioning temperature setting in winter or increase the indoor air conditioning temperature setting in summer for the purpose of saving building energy.Meanwhile,the correlation analysis of subjective thermal voting with skin temperature,core temperature,and heart rate variability was performed on the subjects.It was found that the human forehead temperature and heart rate variability index LF/HF showed significant correlation with thermal comfort voting.Forehead temperature and heart rate variability index LF/HF can be used as important physiological parameters to characterize dynamic thermal comfort.Moreover,correlation analysis of skin temperature and heart rate variability in subjects revealed that mean human skin temperature was significantly correlated with LF/HF in the winter temperature drift experiment.This confirms that the operation of human thermoregulatory mechanisms is influenced by the autonomic nervous system.Secondly,the changes in salivary IgE concentrations in winter and summer temperature drift experiments were investigated.It was shown that cold stimulation from temperature drift in winter induced humans to increase salivary IgE secretion and raise the level of human respiratory immune response.During the upward temperature drift stage of the summer experiment,IgE concentrations decreased in temperature conditions that deviated from the comfort zone(22°C/28°C),and IgE concentrations of subjects in the comfort temperature condition(25°C)decreased and then rebounded.Also,the correlation analysis of human salivary IgE concentration changes with thermal voting,skin temperature,and core temperature during the experiment was conducted.The results showed that the changes of human salivary IgE concentration were significantly correlated with thermal sensation voting during temperature drift,while the changes of human salivary IgE concentration were significantly and positively correlated with thermal comfort voting at stable temperature.Moreover,changes in human skin temperature were significantly correlated with changes in salivary IgE concentration,which confirms the close correlation between human thermoregulatory mechanisms and respiratory immunity.It is important to create a healthy and comfortable indoor environment.Combining dynamic thermal comfort with respiratory immunology,this paper explores the effects of temperature drift on human comfort and health in air-conditioned environments in winter and summer.Further new research ideas were provided for the operation of indoor air conditioning.