160 Sansome Street in San Francisco is a commercial office building that was a pilot demonstration site in LBNL's Diagnostics for Commissioning and Operation project in 1998 and 1999. During the project an innovative Information Monitoring and Diagnostics System (IMDS) was installed. The IMDS collected data with higher frequency, higher accuracy, more advanced data visualization, and more data points than typical Energy Management Systems (EMS) found in buildings. After the completion of the project, the building management and operations staff performed a controls system retrofit which was based on the IMDS, completed in early 2001. After over a year of use, significant energy savings and occupant comfort improvements have been achieved. In this talk, Fred Smothers, formerly with the building's property management and who wrote the specifications for the new control system, will discuss the upgrade of the IMDS to a fully functional EMS. In particular, he will discuss the impact of the data visualization capabilities that were used to optimize plant performance and allow the operators to tune the control loops. Some of his experiences with this control system and other modern control systems will be compared.