This paper presents a screening methodology for estimating potential energy savings from existing building-commissioning/ retrofit measures prior to conducting an audit or assessment. This methodology compares the measured consumption of the building with the consumption predicted by an optimized simulation based on the modified bin method. The method is illustrated with application to a commissioned existing building; results show that the potential for savings from resetting minimum airflow in this building is significant (20% and 54% during occupied and unoccupied periods, respectively) while additional savings obtainable by resetting the room temperatures, cold deck leaving air temperature, and outside air intake are limited (7% and 12% during occupied and unoccupied periods, respectively).