Large, multi-building portfolios can contain buildings of many different ages and use types. However, they all require monitoring and continuous or retro-commissioning to maintain their optimum energy efficiency. The reality of value engineering and expedited timelines to occupancy often renders even new commercial buildings less energy efficient than intended. This can leave the owner with a need to perform formal energy audits and retro-commissioning within the early life of the building. Cushman & Wakefield has implemented a phased and multi-pronged process to optimizing and maintaining energy performance of the client's home office campuses in St. Louis, MO and Tempe, AZ.