Study On Application Of BIM In Retrofit Envelope Of Buildings

The buildings in China have both a huge stock and single function.Under influence of the call of the national energy policy and the increasing requirements on comfortable living,retrofit in buildings began to spread throughout the country.For different regions of China,affected by different needs and climate,the focus on energy-saving transformation is also different.Due to the important role of the envelope in the overall heat transfer of the buildings,its retrofit is the main means of energy-saving in building.Although our country has learned a lot in the development of the retrofit of the buildings,there are still many problems.First of all,the architectural design drawings are old,and many drawings and documents have been damaged,which result in a lack of building information.Secondly,due to the space constraints on the existing buildings,which makes the actual transformation difficult to be consistent with the design drawings,especially for abnormity building envelope,the construction of heat preservation material is difficult.Finally,there are coordination difficulties among different majors in actual construction,which result in the increasing of change,and affect the cost of retrofit.The introduction of BIM will effectively solve the above problems in retrofit of the building envelope.BIM is the informinization construction on the whole building,which makes the building models contain different geometric information(shape,size,etc.)and nongeometric information(heat transfer coefficient,manufacturer,etc.),the integration of different areas and simulation of construction operations help to solve the problem before retrofit.In this paper,BIM is applied in the case of the retrofit on building envelope,and the application of core modeling,energy consumption simulation and cost estimation is studied.Firstly,the retrofit schemes is proposed and modeled by Revit,and the structure and physical properties of building envelope are embodied in the model.Secondly,DeST is used to simulate the energy consumption of different schemes.The energy saving rate of the three retrofit schemes is 61.48%,67.37%,54.61%.Thirdly,the application of the GCL and the GBQ in calculating the retrofit costs in these three programs and they are 255778.55 RMB,295895.3 RMB,237363.39 RMB.Finally,the dynamic payback period of the three transformation schemes is calculated as 11.51 years,12.45 years and 12.25 years respectively.Through the analysis of the actual case,the thesis verifies the fluency and feasibility of BIM in the application of retrofit in building envelope.It also summarizes the problems existing in retrofit of building envelope during the transformation from Revit to Glodon and the improvement direction in the application of BIM.