Due to the increase of carbon dioxide and building regulations, BIM is considered a way of low-carbon and eco-friendly building development for its many advantages. The advantages can be maximized with Open BIM since it can produce optimal results for various purposes of energy performance assessment. However there are some problems in data interoperability in the process of Open-BIM based energy performance assessment. To solve such problems, this study focuses on space boundary information interoperability between IFC of Open BIM and IDF format of Energy Plus known as the most accurate and diverse energy performance assessment. The study analyzes the analogous study then figures out the problems of IFC based energy performance analysis, and suggests the way of interoperability. Finally, the development of automation program makes this way much more effective. The study of IFC data interoperability is useful for improving the reliability of Open-BIM based energy assessment.