The Research On Energy-saving Optimization Design Of Prefabricated Concrete Building Envelope

At present,our country’s building energy consumption accounts for more than 20%of the national energy consumption,and with the development of society and people’s pursuit of a high standard of living,this proportion will be further increased.Building energy efficiency is becoming more and more important,and improving building energy efficiency is one of the best ways to achieve building energy efficiency.As the country attaches importance to building energy conservation and housing industrialization.Prefabricated buildings have won national approval and promotion due to their high degree of industrialization,high precision of prefabricated components,five sections and one environmental protection,information management,and reduction of on-site wet work,etc.Therefore,it is of great significance to study the energy-saving technology of prefabricated buildings.Based on the prefabricated residential buildings in Zhengzhou,a typical city in the cold region,this paper focuses on the energy-saving optimization design method of the prefabricated concrete building envelope through a combination of theoretical analysis and numerical simulation.Nine kinds of building energy-saving schemes are proposed,and five schemes are selected to conduct energy consumption simulation analysis and comprehensive evaluation of scheme applicability based on examples.The main conclusions are as follows:(1)Put forward relevant suggestions for the main energy-saving problems of prefabricated buildings in Zhengzhou.Then clarify the direction and focus of the next step in the energy-saving optimization design of the prefabricated building envelope in this area:Optimizing the insulation thickness of external walls and roofs,Optimization of window type and window-to-wall area ratio,optimization of external window shading measures.(2)Calculate the minimum thickness of the selected insulation material according to the specification,the results show that the minimum thickness of each insulation material in the wallboard is 70mm for EPS board,60mm for XPS board,80mm for rock wool board,50mm for rigid polyurethane insulation board,and 70mm for phenolic board.The minimum thickness of each insulation material in the roof is 80mm for EPS board,70mm for XPS board,90mm for rock wool board,60mm for rigid polyurethane insulation board,and 80mm for phenolic board.(3)Change the thickness of each insulation material on the exterior wall and roof,and use DeST-h to perform energy consumption simulation analysis on the basic model.The results show that the appropriate thickness of each insulation material in the wall can be 80mm for EPS board,80mm for XPS board,and 100mm for rock wool board,Hard polyurethane insulation board 70mm,phenolic board 90mm,the appropriate thickness of each insulation material in the roof can be respectively EPS board 90mm,XPS board 80mm,rock wool board 90mm,rigid polyurethane insulation board 80mm,phenolic board 100mm.(4)Choose ten types of exterior windows and use DeST-h to simulate the energy consumption of the basic model under different orientations and window-to-wall ratios.The results show that the north,east and west exterior windows of prefabricated residential buildings in Zhengzhou area should first choose exterior windows with low heat transfer coefficient,and minimize the window-to-wall ratio.The south exterior windows should also be given priority to select exterior windows with low heat transfer coefficient,while considering the influence of solar heat gain coefficient of building energy consumption.When window10#is selected,the window-to-wall ratio should be 0.4,and for window9#,the window-to-wall ratio should be about 0.5,and for other types of exterior windows,the window-to-wall ratio should be minimized.When considering sun-shading measures for the south-facing windows,priority is given to ordinary sunshades,and blinds are preferred,the window-wall ratio can be appropriately increased on the basis of meeting lighting,ventilation and sunshine.(5)Taking a residential building in Zhengzhou as an example,the energy consumption simulation comparison and analysis of different building energy saving schemes are carried out.The results show that rigid polyurethane insulation boards should be the first choice for the thermal insulation materials of the prefabricated residential buildings in Zhengzhou.When designing energy-saving buildings,the shading measures,the types of south-facing windows and their window-to-wall ratios should be emphatically considered.(6)Use the comprehensive method of superiority and analytic hierarchy process to comprehensively evaluate the applicability of the five selected energy-saving schemes.The results show that the applicability of the prefabricated building scheme is higher than that of the uninsulated and external thermal insulation schemes,and it proves that it is necessary to optimize the design of the energy-saving exterior protection structure of the prefabricated building;for the schemes with relatively close relative superiority,similar energy-saving optimization design can be carried out reasonably in the project to determine the final scheme.