||Over the course of simulation performances, the existing buildings' current situation of energy consumption is diagnosed, and the effect of improving energy performance is predicted in early planning stage. However, it is difficult to ensure the level of information required to perform the simulation. The main issues are the aging condition assessment, omission of required information of the building, and the differences between the documentations and the actual status of the existing building. BIM-based building information is able to digitalize and organize the documented building information and add changed or missing information in the field thereafter. In addition, a variety of tools and information increasing the compatibility are opening the potential uses for the remodeling. However, utilizing BIM for remodeling is not the norm, and the feedback-able actual operational problems information is insufficient. In this paper, the possibility of utilizing BIM-based remodeling is analyzed through a comparison of the existing and the BIM-based building energy analysis process of remodeling, and then the optimizing methods of remodeling process of the existing building is sought.