Study On Thermal Environment And Thermal Comfort Of School Buildings In Severe Cold Region

Classroom's thermal environment and thermal comfort not only directly affect students' learning efficiency,but also determine the energy consumption level of the school building.On the one hand,it is urgent to improve global warming due to the accumulation of greenhouse effect caused by the emission of greenhouse gases,which leads to a series of environmental problems.According to statistics,35% to 40% of the carbon dioxide emissions in the greenhouse gases causing global warming are from buildings.Optimizing the indoor thermal environment of buildings is conducive to reducing building energy consumption and improving global warming.On the other hand,related studies have shown that at least 90% of one's life time is spent indoor,indoor thermal environment directly affects people's physical and mental health and work efficiency,especially the construction of colleges and universities,the thermal environment directly affects the students' physical and mental health and learning efficiency,improve thermal comfort of students classroom group has significant meaning.But affected by factors such as solar radiation,heating,indoor thermal environment is usually uneven.Non-uniform thermal environment leads to different indoor thermal comfort level,although together in one room,different regions of personnel's subjective hot feelings can also be very different,especially for the teaching building,the location of the indoor personnel and flexible variability is poor,when the thermal comfort of students in different indoor areas is different,it will lead to different learning efficiency.If the indoor thermal environment and thermal comfort zones can be established according to the factors causing uneven indoor thermal environment,the targeted local optimization of different indoor areas is likely to improve the thermal comfort of people in each zone with the minimum energy consumption to the greatest extent,so as to achieve the purpose of energy conservation and emission reduction.This study selected an ordinary classroom in Harbin Institute of Technology.The thermal environment of the classroom was measured and analyzed respectively in the most representative period of temperature in winter and summer(the lowest temperature in winter < 20? and the highest temperature in summer > 30?).According to the main factors that cause the inhomogeneity of indoor thermal environment in winter and summer: convective heating radiation and solar radiation,the indoor thermal environment was partitioned(window area,middle area and door area)and experimental instruments were arranged.In order to synchronously analyze the thermal comfort of the personnel in each division of the room,the thermal comfort questionnaire was issued to the personnel in each division during the measurement of the thermal environment,which was filled in every ten minutes.Finally,the obtained subjective and objective experimental data and questionnaire contents are compared and analyzed,the indoor thermal environment partition is comprehensively evaluated,and the thermal environment optimization strategy is proposed for winter and summer working conditions.The result shows that both solar radiation and convective heating radiation can cause the inhomogeneity of indoor thermal environment,making it appear the phenomenon of temperature and humidity partition on the horizontal plane and the vertical plane,and the indoor thermal comfort also appears the phenomenon of partition on this basis.For solar radiation in summer,the window area that can be directly hit by the sun indoors has the highest temperature and the lowest thermal comfort.For the convection heating radiation in winter,the window zone near the heater has the highest temperature and the lowest thermal comfort.On the whole,during the test period,the maximum temperature difference in the horizontal plane of each partition of the classroom under test can reach 0.7? in summer and 2? in winter,indicating that the influence of convective heating radiation on indoor thermal environment heterogeneity is more significant than that of solar radiation.In addition,the overall thermal comfort of indoor personnel in winter is higher than that in summer.In view of the experimental results,this study suggests that the indoor thermal environment should be further partitioned based on the indoor and outdoor partition,and based on the cold and heat radiation factors.According to the experimental results in summer,Airpak simulation shows that the shading facilities and natural ventilation can effectively reduce the influence of solar radiation and reduce the overall indoor temperature.In order to further improve the thermal comfort of the staff in the window area and avoid the influence of winter sunshine,this study suggests that the corresponding adjustable external shading facilities should be adopted for the facade of the teaching building under test,and the doors and Windows of the classroom should be opened for natural ventilation during class break.According to the experimental results in winter,based on the characteristics of indoor thermal zoning and the lower limit of acceptable temperature for office buildings in cold regions,the recommended indoor heating design temperature value of 20? was proposed in this study for the space types of classrooms tested.In addition,in order to effectively improve the thermal comfort of staff,the study area of indoor staff should be reasonably planned according to the specific partition characteristics of indoor thermal environment,so as to improve the thermal comfort of indoor staff in each area as much as possible on the basis of saving energy consumption.