Research On Energy-saving Renovation Strategy Of Rural Residential Buildings In Northern Guizhou Based On BIM Technology

Building energy conservation in rural areas has become an important part of building energy conservation system engineering in China.However,the rural residential buildings in northern Guizhou have high building energy consumption due to the poor thermal performance of external envelope,indoor thermal environment and light environment.In this paper,BIM technology simulation method is used to study the energy-saving transformation strategy of rural residential buildings in northern Guizhou,which provides new ideas for rural energy-saving transformation.The main conclusions are as follows :Firstly,after field research and physical thermal environment measurement method,the four villages in Bozhou District of northern Guizhou Province were studied on family characteristics,architectural form characteristics,enclosure structure characteristics and physical thermal environment.The results showed that : Modern houses in northern Guizhou Province were mostly built before 2010,accounting for about 79.79 %.Most of the buildings are mostly two-storey,three-bay,and two-depth.The area is mainly about 201 ~ 250 m2.The storey height is concentrated in 3m to 3.3m,accounting for about 75.01 %.The largest proportion of the enclosure structure is the aluminum alloy single-layer outer window,wooden outer door,clay brick outer wall and small tile slope roof.While Traditional houses were built in the seventies and eighties.The buildings are mostly single-layer three-span two-depth.The area is mostly about 110 m2.The indoor net height of traditional dwellings is mostly between 2 m and 2.4 m.In terms of the enclosure structure,wood windows,Chinese fir board / bamboo sandwich wall,wood doors and small tile slope roofs account for the largest proportion of traditional houses.Based on the summary of the survey,the typical models of modern and traditional houses are proposed,which lays the foundation for subsequent simulation analysis.Secondly,by using the AHP method,an index system of factors affecting energy consumption in the energy-saving renovation of residential buildings in northern Guizhou is put forward.The layout of surrounding buildings,wind direction and speed,planting soil profile,building orientation,building shading,window-to-wall ratio,building indoor net height,roof heat transfer coefficient,average heat transfer coefficient of external walls,heat transfer coefficient of external doors and windows,and exterior sun absorption coefficient,air tightness are involved.Then the BIM energy consumption simulation analysis method is used to analyze the factors of the energy simulation analysis: light environment,wind environment,thermal performance of envelope structure,building interface and form,building exterior shading and the lower-level indicators of each index to conduct single-factor analysis and research,revealing the law between the influencing factors of each single energy consumption and energy consumption.Lastly,the orthogonal experiment method is applied to use the L25(56)orthogonal table to determine the traditional residential roof heat transfer coefficient,external wall heat transfer coefficient,building indoor net height,external window heat transfer coefficient,south-facing window-to-wall ratio,and solar absorption on the exterior surface.Factors and energy consumption influencing factors such as exterior wall heat transfer coefficient of modern residential buildings,roof heat transfer coefficient,building interior height,exterior window heat transfer coefficient,exterior solar absorption coefficient,horizontal sun visor length and other energy consumption factors are subjected to orthogonal scheme simulation research and quantification,which summarizes the law of influence on energy consumption by the factors affecting the energy-saving renovation of rural residential buildings in northern Guizhou under multiple factors: the primary and secondary order of modern residential factors is external wall heat transfer coefficient>roof heat transfer coefficient>building interior net height>external window heat transfer coefficient>outside The solar absorption coefficient of the facing> the length of the horizontal sun visor.Traditional houses are roof heat transfer coefficient>external wall heat transfer coefficient>building interior clear height>external window heat transfer coefficient>external surface solar absorption coefficient>south window-to-wall ratio.Provide theoretical guidance for the subsequent proposal of energy-saving retrofit strategies.Thirdly.On the basis of the above field research,AHP method and the energy consumption influencing factors of BIM technology simulation,the principles of priority of external envelope,appropriate technical and economic low cost,unified style,structural safety and minimal impact on life are proposed.The recommended value of the best orientation of the building is 10 degrees south east.In terms of the window-wall ratio,when the window is opened in the north-south direction,the window-wall ratio in the south direction is 0.17 – 0.45 for the traditional residential buildings.The window-wall ratio in the north direction is 0.17 – 0.4.Only the south direction allows the window-to-wall ratio to be 0.6.For modern residences,the south window-wall ratio is0.24 ~ 0.45 and the north window-wall ratio is 0.24 ~ 0.4.Only southwards allow window-wall ratios to 0.6.The recommended value of indoor net height of traditional dwellings in northern Guizhou is 2.8 m,and the current dwelling is 3 m.On the reconstruction strategy of enclosure structure,based on the reconstruction principle,it is suggested that the external insulation form of enclosure structure exterior wall should be selected,and EPS can be selected for insulation and energy saving reconstruction.The modern roof houses are laid with insulation layer on the roof floor under the small green tile.XPS can be selected as insulation material for renovation,the traditional residential roof is suspended in small green tile roof 600 mm after XPS energy saving renovation.On the outer window,different houses are selected according to different situations, including changing the outer window,changing single-layer window into double-layer window,and increasing air tightness.Outside door can increase the thickness of existing Chinese fir door or replace insulation door directly.On the ground,modern dwellings recommend overhead ground renovation,while traditional dwellings adopt dry slag ground renovation.On the external shading of buildings,traditional dwellings should not use external shading of buildings,and modern dwellings are recommended to use 0.6 m comprehensive shading.In terms of the external environment transformation strategy,it is recommended to use green planting wall,westward pool and hard softening to transform the outdoor environment of residential buildings.Finally,the simulation scheme is verified,and the whole life cycle method is used to study and determine that the thickness of the EPS insulation layer on the exterior wall of modern residential buildings is 60 mm,and the thickness of the XPS insulation layer on the roof is40 mm.The economical thickness of the traditional residential insulation layer is 60 mm for the EPS insulation layer for external walls and 30 mm for the XPS insulation layer on the roof.Found by BIM Simulation Software.The energy saving rate of traditional residential buildings is 44.1 %,and the energy saving rate of modern residential buildings is 56.6 %.As for the heat gains and losses which has been reduced by about 70% in traditional and modern residential enclosure structure throughout the year.In the thermal environment,the indoor temperature of traditional dwellings in summer after reconstruction is about 1.97 °C lower than that before reconstruction.Winter is about 1 °C higher.The indoor temperature of modern residence after reconstruction is about 1.91 °C lower than that before reconstruction,and about 1 degree higher in winter.In the light environment,the traditional residence increased by about 76 %.In the wind environment,the indoor wind speed of traditional dwellings decreases obviously in winter.The results show that this method has good applicability and can bring good energy saving benefits for rural residential buildings.