Research On Energy-saving Optimization Of External Window Structure System Of Prefabricated Teaching Building In Cold Area

In 2020,building and construction energy consumption accounted for 45.5% of China’s total energy consumption,reaching 2.27 billion tce.The construction industry needs to change the construction mode.School buildings consist of several unit spaces,which are well suited to modular design thinking nature and can complement the characteristics of assembled buildings.In terms of energy efficiency,assembled buildings are unable to avoid thermal bridges during installation due to factors such as docking technology and the way components are connected to each other,making the building more energy efficient.Windows,as the weak link in the envelope,are a prominent problem in terms of energy consumption in assembled buildings.In particular,the requirements for light and ventilation and comfort in the indoor use space of assembled teaching buildings are high,and due to the large number and volume of windows,the annual energy dissipated through thermal bridges at the node connections of external windows accounts for a significant proportion of the total building energy consumption,so it is necessary to carry out energy-saving optimisation studies on the external window construction system of assembled teaching buildings.This paper combines the climate conditions in the cold area of Yantai,takes the connection between prefabricated exterior windows and prefabricated exterior wall panels of the assembled teaching building as the base model,selects three assembly methods of prefabricated exterior windows hanging out,overhanging and embedded in the prefabricated exterior wall panel reserved window openings for research,and uses the parameters of temperature distribution map at the thermal bridge,linear heat transfer coefficient and average heat transfer coefficient of the exterior wall under the changes of insulation layer thickness,thickness of covered prefabricated exterior windows,etc.as The thermal bridge at the connection between prefabricated exterior windows and prefabricated exterior wall panels of the assembled teaching building is analyzed as a key index for the heat transfer effect on the enclosure structure,and the simulation analysis is carried out based on PTemp two-dimensional heat transfer calculation software.The main research content of this paper can be divided into three parts as follows.Firstly,this paper reviews the research literature on assembled teaching building architecture at home and abroad,sorts out the theories related to assembled architecture and teaching building architecture,and elaborates the fit between assembled architecture and teaching building architecture.Based on the architectural design process of the teaching building based on the application of assembly technology,the building energy consumption simulation analysis is carried out starting from the node structure at the connection between prefabricated exterior windows and prefabricated exterior wall panels.Secondly,the effect of thermal bridges between prefabricated windows and prefabricated wall panels on the heat transfer to the external envelope in the assembled building is analyzed by using PTemp simulation software.In the simulation of the bridge structure at the connection between prefabricated windows and prefabricated exterior wall panels,the simulation results of heat transfer under the influence of single factor of the bridge structure were analyzed horizontally,mainly under the same thermal bridge type and the same structure type,the influence of the change of the thickness of the insulation layer and the change of the length of the insulation layer covering the prefabricated windows on the heat transfer of the external envelope was compared and summarized,and the influence of the bridge structure at the connection between prefabricated windows and prefabricated exterior wall panels on the heat transfer coefficient was compared and summarized.The effect of different prefabricated windows and prefabricated exterior wall panels on the heat transfer coefficient was compared.Among them,model a4 is the best when the connection between prefabricated windows and prefabricated facade panels is external hanging type,and the heat transfer coefficient of this construction line = 0.126 W/(㎡-K);model b4 is the best when the connection between prefabricated windows and prefabricated facade panels is overhanging type,and the heat transfer coefficient of this construction line =0.100 W/(㎡-K);the heat transfer coefficient of prefabricated model c4 is the best when the connection between the exterior window and the prefabricated exterior wall panel is taken inline,and the heat transfer coefficient of this construction line = 0.083W/(㎡-K).Finally,according to the simulation results,the optimized scheme design and improvement measures are proposed for the broken bridge construction at the connection between prefabricated exterior windows and prefabricated exterior wall panels.Considering the research results,heat transfer coefficient,economic feasibility,building construction and later maintenance problems,it can be seen that the design scheme of the broken bridge construction at the connection between prefabricated exterior windows and prefabricated exterior wall panels has a significant impact on the energy saving of the assembled school building in cold regions,and its reasonable optimized design scheme should be scientifically evaluated.