Research On Carbon Emission Calculation And System Dynamics Simulation Of Prefabricated Building

With the rapid development of economy and society,global greenhouse gas emissions have increased and the problem of climate warming has become increasingly serious,the construction industry has become an important area for energy saving and emission reduction.Accelerating the transformation of the industry and promoting the development of the prefabricated building industry is a necessary path for the healthy development of China’s construction industry,so it is important to explore the emission reduction capacity and carbon emission trends of prefabricated buildings.In this paper,the whole life cycle carbon emission measurement is carried out with a single building as the research object,the factors influencing carbon emission of prefabricated buildings in Xi’an are identified,the causal relationship and feedback mechanism of each influencing factor are revealed using the system dynamics method,and the development trend and emission reduction effect of the industry are simulated.The main research results of the paper are as follows:(1)The carbon emission of a whole life cycle of an prefabricated building was measured.Based on the digital modeling and pricing software,the whole life cycle of a single building was divided into six stages,and carbon emissions were measured in each stage by using the carbon emission factor method,and the assembly method was compared with the cast-in-place method.The results show that the carbon emission of the whole life cycle of the project is 32422.43t,among which the operation and maintenance phase generates the most carbon emission,and the production phase of building materials in the materialization phase accounts for the largest carbon emission.Compared with the traditional cast-in-place method,the emission reduction effect of the assembly method is significant,with 18.51 kg of carbon emissions reduced per unit area in the materialization stage,and the emission reduction effect is mainly in the construction stage,accounting for 50.89%of the total emission reduction.(2)The index system of carbon emission influencing factors of prefabricated buildings was constructed.The Kaya constant equation method and LMDI index decomposition method were applied to sort out the influencing factors of carbon emission of prefabricated buildings,while 20 influencing factors were identified from five levels of socioeconomic,governmental decision making,market scale,technical environment and building energy consumption by using literature research method,and an evaluation index system of carbon emission of prefabricated buildings was constructed,and the weight of each factor index was determined by applying hierarchical analysis method and entropy weight method.The results show that the government decision-making level and the building energy consumption level are the important indicators affecting the carbon emission model of prefabricated buildings,where the influencing factor with the greatest weight is the building energy structure and consumption,followed by the standard and specification system.(3)A system dynamics model of carbon emission of prefabricated buildings was established.Based on the system dynamics theory,we established the carbon emission model equations of prefabricated buildings and drew the causal loop diagram and the stock flow diagram to carry out model simulation analysis,policy analysis and trend prediction.By setting different scenarios,we analyzed the sensitivity of five types of sensitivity parameters to the system,screened the preferred path and provided suggestions for policy adjustment and enterprise development.The results show that the market share of prefabricated buildings will reach 40.8%in 2030,and the adoption of prefabricated approach instead of single traditional approach is expected to achieve the target of 12,929,700 tons of emission reduction in 2030.The optimal path is to reduce the incremental cost while accelerating the construction of standard system in the two-factor scenario combination,based on which the scale and lowcarbon development is proposed.