Thermal Comfort In Dynamic Environment Under Temperature Step Conditions

In this paper, one experimental research by creating different transientenvironments with different temperature differences was carried out in artificial climatechamber with20healthy college students in the summer and winter of2012. Weselected the thermal environment with three temperature differences in winter andsummer respectively, analyzed the effect of temperature transient condition on surfaceskin temperature and the change rule of the subjective thermal sensation of human body.The experimental result shows that human body response differently to the cold and hotstimulation, mainly expressed that human body is more sensitive to cold stimulation,while insensitive to hot stimulation under the temperature transient environment. Underthe effects of thermal stimulation we found that the most sensitive parts roughly werehead, back, chest in the warm environment, and were head, thighs, legs, hands in thecold environment. Based on the sensitive parts of the human body in winter and summer,we put forward the suggestion that in view of the above several parts，we could adoptthe way of station air conditioning to improve the human body thermal comfort.In the study of the relationship between thermal sensation and mean temperature,we found that the skin temperature can better predict thermal sensation in steadythermal environment, but in the temperature transient environment，for the influence ofthermal experience，the relationship of them is discrete, it cannot be used to predicthuman thermal sensation, at this point, using the air temperature to predict thermalsensation is more accurate than the skin temperature. And in the instantaneous oftemperature transient, the change rate of skin temperature had a greater influence onthermal sensation, after that，the skin temperature and change rate of skin temperaturehad a little effects on thermal sensation.On the analysis of special thermal response to the temperature transientenvironment，it can be found that psychological and physiological responses of humanbody were in dynamic processes, psychological responses were more rapidly thanphysiological responses. In addition, the thermal experience before the temperaturetransient would greatly influence the change of later thermal sensation, skin temperature,thermal neutral temperature thermal acceptance of thermal shock and thermal comfortstate. The temperature down-steps condition in summer would bring the "cooling effect"to human body, the overshoot in thermal sensation was found, and as the increasing of temperature difference, the more obvious the "cooling effect", the longer time it wouldcontinue. Based on the special phenomenon, we developed the regression model ofdynamic thermal sensation to predict the thermal sensation in the process from warm toneutral environment.Transition spaces were places for short staying, it is unable for people to avoid thethermal shock due to the great temperature steps in summer when we enter suchworkplaces. Based on the special dynamic thermal responses characteristic of humanbody found in the experimental research, from the three aspects of the lower energyconsumption, to meet human body thermal comfort, reduce the effects of thermal shockon the human health, we proposed the dynamic air conditioning control strategy thatsuitable for the transition space in summer.