Abstract: In order to comply with the national policy of building industrialization and intelligent development and solve such problems as the disconnectedness to professional information, insufficient use of models, and low efficiency of data transmission, a top-down design method based on the building information modeling (BIM) technology was proposed. Starting with the design stage of prefabricated building, the BIM technology-based top-down design process of prefabricated building was elaborated in detail. Combined with the characteristics of standardized component design and assembly of prefabricated buildings, an assembly model based on top-down design was proposed, and the structure of the model was described from the perspectives of hierarchy and specialty. To tackle the problems of standardization and consistency of data information during the transmission of professional models, the entities and property sets of assembly model were extended based on the industry foundation classes (IFC) standard, and the information collaboration using the IFC standard-based top-down design was proposed for each specialty and each stage. Finally, the application of the example verified the feasibility of the IFC-based top-down design of the extended assembly model, which can provide a useful method for collaborative design of prefabricated buildings. 

Key words: building information modeling, top-down design, assembly model, industry foundation classes extension; collaborative design