Abstract : The importance of energy efficiency and integration of advances in building design and VR technology have led this research to focus on thermal simulation results visualized in a virtual environment to optimize building design. This paper combines the principle of integration for thermal calculation and scientific visualization in VR. The method is to use CAD models (extensively used in architectural design) to analyze a building's thermal performance and visualize it, as well as simulating it through VR technology. Interaction between users and objects in a virtual world are certainly through techniques of visualization metaphors. The object of the experiment was the Gunzo room, located in an old building on the historical site of the Cluny Abbey in France. An application and an experiment scenario of a thermal simulation was created to interactively visualize the results in the immersion room, and tested by some participants. The experiment was conducted to simulate object-based data models that are specific to the thermal domain, using tools provided by the IFC format. This choice was made to overcome the limitations of general-purpose geometric representations, particularly in data exchange among the selected tools used for the simulation. Analyzing the application has demonstrated that it is possible to conduct a specific data workflow in order to represent building performance data, and particularly thermal simulation results in VR. With this integration method, the data flow that starts from the design process is completely and accurately channeled to the VR system.