Study On Indoor Thermal Environment Evaluation And Optimization Design Of Ankang

Ankang,Shaanxi is located in a hot summer and cold winter area,belonging to a region without centralized heating in winter.The climatic characteristics are hot and humid in summer and cold and humid in winter.Rural residents rarely use equipment to improve the indoor thermal environment of buildings.Therefore,the study of the indoor thermal environment of rural residential buildings in Ankang has important significance.Taking the indoor thermal environment of rural residential buildings in Ankang as the research object,aiming at improving the indoor thermal environment of rural residential buildings in Ankang,through field visits,surveys,physical parameter measurements,analyzing the existing problems of the indoor thermal environment of local residential buildings,which are the lack of targeted thermal environment evaluation indicators and poor indoor thermal environment in winter.Follow-up research is carried out for the existing problems.Through field investigation and questionnaire interview of rural residential buildings in various counties and districts of Ankang,we understand their architectural characteristics and residents’ living habits and actual thermal sensation,and select typical residential buildings for on-site measurement of indoor thermal environment,study the local residents’ thermal sensation and thermal environment improvement needs in summer and winter,and determine that the optimization focus of Ankang residential buildings’ indoor thermal environment is winter insulation,with proper consideration of summer heat prevention.By comparing PMV-PPD and MTS results,it is found that PMV-PPD model cannot accurately predict the thermal environment of Ankang residential buildings,so PMV-PPD model is revised,and the local residents’ thermal comfort operative temperature range is obtained by data calculation and fitting,which is: 20.7～29.7℃ in summer,neutral temperature: 27℃.Winter: 6.9～15℃,neutral temperature: 13.5℃.The revised PMV-PPD model is used as the adaptive evaluation indicator of Ankang residential buildings’ indoor thermal environment,and the evaluation standard of Ankang residents’ thermal comfort operative temperature range is used to provide theoretical basis for the evaluation of indoor thermal environment of residential buildings in Ankang area.The roof,external wall,window-wall ratio,external window material and external shading are determined as the influencing factors of indoor thermal environment.The indoor thermal environment of Ankang residential buildings throughout the year under different factors is simulated by Design Builder software,and the simulation data are compared and fitted.It is found that the total value of thermal discomfort hours in winter and summer increases with the increase of heat transfer coefficient of roof,external wall and external window.Among them,the heat transfer coefficient of roof should be less than or equal to0.8W/ ㎡ ·K;The heat transfer coefficient of external wall should be less than or equal to1.5W/㎡·K;The heat transfer coefficient of external window should be less than or equal to3.2W/㎡·K.There is no obvious linear relationship between window-wall ratio and external shading coefficient and thermal discomfort hours.According to the change curve of total value of thermal discomfort hours in winter and summer and standard regulations,it is determined that the value of south-facing window-wall ratio should be 0.2～0.3,and comprehensive shading should be selected for external shading with optimal shading coefficient of 0.74.Through single factor analysis,taking roof,external wall,external window heat transfer coefficient,south-facing window-wall ratio as factors,a four-factor four-level orthogonal experiment was conducted.Through range analysis,the primary-secondary relationship of each factor affecting Ankang residential buildings’ indoor thermal environment was obtained,namely roof heat transfer coefficient > external wall heat transfer coefficient > south-facing window-wall ratio > external window heat transfer coefficient.At the same time,the optimal level value under each factor was determined,and the theoretical prediction optimal combination for optimizing indoor thermal environment was obtained: roof heat transfer coefficient was 0.4W/ ㎡ ·K,external wall heat transfer coefficient was 0.6W/ ㎡ ·K,window-wall ratio was 0.2,external window heat transfer coefficient was 2.4W/㎡·K.Optimization strategies are proposed for roof,external wall,external window and external shading,namely roof adopts ventilated insulation roof with 69 mm thick EPS polystyrene board as insulation material;External wall adopts external insulation with 37 mm thick EPS polystyrene board as insulation material;The south-facing window-wall ratio should be set to 0.2;External windows use 50 mm thick wood as window frame,with double glass hollow glass structure of 6mm+12mm Air+6mm;External shading adopts comprehensive shading with horizontal shading board protruding 165 mm outward and vertical shading board protruding 230 mm outward.It is expected that the proposed optimization design strategy can provide reference and guidance for the optimization of Ankang residential buildings.