Research On Indoor Thermal Environment And Human Thermal Comfort Of Teaching Buildings In Colleges And Universities In Xi’an In Winter

With the development of society and the continuous improvement of education level,people pay more and more attention to the advantages and disadvantages of the classroom thermal environment and indoor thermal comfort,which is not only related to the physical and mental health of students and teachers in the classroom,but also directly affects the learning efficiency of students,and then affects the quality of school teaching.This paper studies the indoor thermal environment and human thermal comfort of teaching buildings in Xi’an in winter.Firstly,the thermal environment parameters of typical classrooms were tested by subjective questionnaire survey and objective field test at the same time,and the thermal comfort status of university classroom staff was obtained.Secondly,the software was used to simulate the indoor thermal environment of university teaching buildings in Xi’an in winter,and the effects of different indoor relative humidity,radiator surface temperature and indoor wind speed on human thermal comfort were analyzed The influence of comfort index PMV and PPD.The main conclusions are as follows:(1)The average clothing thermal resistance of college students in Xi’an in winter is 1.2 clo,which is higher than 0.9 clo in ashrae55-2013 standard.The clothing thermal resistance of male students is significantly lower than that of female students.The results show that the measured thermal neutral temperature is 16.3 ℃ and the predicted thermal neutral temperature is 17.0 ℃.The students’ clothing has high thermal resistance,the regulation of psychological expectation and the physiological characteristics of high metabolic rate,which make the students’ thermal neutral temperature in Xi’an lower.(2)The relative humidity range of the air in this test is 30.3%-50.9%.The test results show that low humidity(relative humidity below 60%)has no obvious effect on human thermal sensation.At the same time,it also shows that people’s sensitivity to temperature change is higher than that when the air relative humidity is below 60%.(3)Xi’an university students are not satisfied with the relative humidity,temperature and smell in the classroom in winter,so their adaptive adjustment behaviors are mainly humidification,drinking hot drinks,opening doors and windows,local heating and light activities.(4)Using the simulation software Airpak to simulate the indoor thermal environment of typical classroom in Xi’an university teaching building in winter,the results show that the indoor temperature has a slight downward trend when the indoor relative humidity changes from 40% to 60% under the same number of students,radiator and external conditions,but the change trend is not obvious,the indoor human thermal comfort is enhanced,and the human body is satisfied with the environment dissatisfaction decreased;when the surface temperature of radiator changes from 45 ℃ to 65 ℃,the indoor average temperature increases,the indoor human thermal comfort increases,and the human dissatisfaction with the environment decreases;when the indoor wind speed increases from 0.1m/s to 0.2m/s,the indoor average temperature is basically in a stable state;when the indoor human thermal comfort decreases,the human dissatisfaction with the environment increases.(5)Coupled with the PMV and PPD model formula of indoor human thermal comfort of teaching buildings in Colleges and universities in Xi’an in winter heating state,the PMV value of human average thermal sensation index and PPD value of predicted dissatisfaction percentage under the comprehensive effect of three independent parameters of indoor relative humidity,radiator surface temperature and indoor wind speed can be obtained,which provides the basis for the indoor design parameter standard of teaching buildings in Colleges and universities in Xi’an.