Significant energy use in heating, ventilating, and air conditioning (HVAC) systems in buildings motivates the potential for improvements in the performance of such systems and their controls. The objective of this study is to customize the minimum airflow ratio setting in a medical facility so that the fan speed and energy level are reduced to conserve energy and, at the same time, the ventilation requirements for the critical zones and the temperature remain at desired levels. A series of tests were conducted in a military medical building in Oklahoma City, Oklahoma. The air-handling units that are used in this study distribute conditioned air to offices and pharmacy spaces. Considering the medical environment, maintaining a proper airflow rate and keeping the temperature at a pre-determined level are critical. This customization is guided by the recent revisions to ASHRAE Standard 90.1. While maintaining 30% minimum air flow during occupied hours for noncritical zones and keeping critical zones intact, our results show that the fan speed declined from 30% to 75% and the energy level declined from 15% to 90% in different units during the experimental period from March 2016 to August 2016. Although the energy savings may vary, lowering the airflow, as guided by the revised ASHRAE Standard 90.1, may lead to a significant decline in the fan speed and in energy consumption.