Effect Of Local Thermal Stimulation On Human Thermal Comfort Under Colder Environment

With the traditional air conditioning system led to "sick building syndrome", andconstantly building energy consumption,forcing people to seek air conditioningsolutions in comfortable, healthy and energy-efficient. In this case, the non-uniformenvironment that the local environment causes has become a hot research. Whilenon-uniform environment in real life is widespread, the study of non-uniform thermalenvironment not only has broad application background, the law will help to reveal thedeep-seated human thermal reactions. Therefore, this paper takes a combination ofinvestigation and experimental studies on human thermal response under coolconditions for exploratory research.Firstly, this paper carried human thermal comfort fieldwork of natural ventilationin Chongqing University classrooms and dormitories in the winter of2012,382validdata were obtained, of which218males,164females. Distribution of winter clothingpersonnel drawn from the analysis of thermal clothing thermal resistance, reflecting atypical winter clothing habits; from analysing local and overall thermal sensation voteanalysis, obtaining the voting of thighs and feet is closer to the overall thermal value,and thermal sensation of lower leg explains the overall thermal sensation changing best,the overall thermal sensation is mainly controlled by the leg, back, forehead and feet.Then, this paper based on field survey findings to choose healthy college studentsas subjects in the school population, In December2013-January2014launched lowerleg thermal stimulation experimental studies under the background condition of12℃and14℃, contrasting background conditions and air condition thermal sensation andthermal comfort of all parts, found thighs, lower leg, feet, overall thermal sensationand thermal comfort are significant appear differences. In addition to backgroundconditions of12℃, the chest and back thermal sensation occurs significant differenceswhen air temperature is52.8℃, and in the background conditions of14℃, the hand andback appeared significantly differences when air temperature are33.2℃and41.5℃,thermal sensation and thermal comfort of other parts was observed unsignificantdifference. And when the background condition of12and14℃，lower leg supply airtemperature ranges of38.7~42.0℃and18.4~28.9℃, the overall thermal sensationreached ASHRAE standards recommended value （-0.5to0.5）. Analysing therelationship between the overall thermal sensation and skin temperature, found that they showed a good linear relationship under steady-state environment, however theyoccurred separation under unsteady-state environment, thermal sensation appeared"ahead" phenomenon.This paper drawed the influence weight of body parts on the overall thermalsensation through principal component analysis when lower leg was stimulated undercolder environment, found the weight coefficient of lower body thermal sensationgreater，the resulting is different compareing that of warmer environment, indicatingthe weight coefficient of local thermal sensation is affected by the backgroundenvironment in some extent. In colder non-homogeneous environment, to explorethermal sensation impacting on thermal comfort, this paper put forward the unevenvariable of thermal sensation included the unstimulated and stimulated parts,andobtaining the prediction model of thermal comfort under the colder and non-uniformenvironment，this model can be used to evaluate the environment.