Buildings consume 39% of the total energy in the United States. To address the urgent challenge to improve the building energy efficiency, numerous digital analysis tools have been developed. However, there is a general lack of interoperability among these tools which limits the collaborative potential or creates added work when using BIM on projects. In order for the industry to solve this interoperability issue in a concerted fashion, an overarching process model describing the building process and the information exchanges within is needed. As integrated design makes it easier for project team to deliver high performance buildings, and HVAC systems are critical to building energy performance, this research has begun to map out the HVAC design process in an integrated design environment, in which various digital tools will be used. With the process maps, the information exchanges among various digital analysis and simulation tools can be identified. The process maps developed by this research can serve as a foundation for the industry to overcome the interoperability challenges. For the design teams that are not familiar with integrated design process, this process model provides a generic guide for design planning.