With the development of design process,the cost of improving building performance by modifying main design parameters will increase dramatically,so decisions made in early design stage are very important.More and more studies focus on the development of performance-orientated design tools,which can provide instant feedback of building performance for designers and inspire them to seek for the optimum building schemes in early stage.These tools can generally convert building geometry model into specified format required by performance simulation software,then the software is launched to compute results,finally the results are feedback to designers.What is the most difficult is that the description of building geometry model and building performance input model(i.e.Building Energy Model)is different.And most designers lack knowledge of building performance because of the disciplinary barriers,it is difficult and time-consuming for them to convert the model.To solve this problem,this paper presents an algorithm that can quickly and automatically convert building geometry model,extract information of building components(floor,roof,wall,window,etc.)and the relationships between them,then stores them in semantic-based hierarchically object-oriented format.Based on the converted model,it is easy to obtain input parameters required by simulation software.This algorithm will be integrated within Sketch Up,and evaluated from the following aspects through case study: 1)recovering designers partition mode which have significant influences on performance indicators; 2)conversion time,which is crucial for its applicability in early design stage.The proposed algorithm can accurately and quickly convert model,conversion time for a building with 600 surfaces was less than 0.215s,compared to the previous work,is performance better in these two aspects at the same time.In the last section we discuss its possible applications and the further work.