Advanced Energy Retrofit (AER) projects can significantly reduce energy consumption of existing buildings, and studies have indicated that they can be more economic than constructing new buildings. Retrofit projects vary in complexity based on the building characteristics, building area, client requirements, project budget, payback period and energy savings targets. The lack of a transparent and streamlined integrative process makes it difficult for the participants to implement AER projects. To implement comprehensive AER projects (also known as Deep Retrofits) in an efficient manner, it is important to understand the process along with the information exchanged during the planning, design, construction and operation phases. This paper describes the development of an AER integrative delivery process model with a focus on the planning and design phases. The integrative process has been developed through a detailed literature review, and studying the project documents and procedures used to deliver an ongoing comprehensive AER project. It was validated by review in multiple industry workshops and through interview with industry and academic experts, including all the primary team members of a comprehensive AER case study. The process is undergoing additional validation through AER integrative workshops and a detailed case study analysis. The final integrative process includes activities focused upon specific building systems along with integrated processes and information exchanges which support the integrated workflow among team members. The identified important information exchanges outline a series of exchanges that support application interoperability for AER projects.