The project objective was to control outdoor ventilation airflow and distribution so that ASHRAE Standard 62-1989 was satisfied while minimizing the impact of energy utilization. The base system Direct Digital Controls (DDC) are application specific, with insufficient custom programming capacity to meet the project objective by themselves. Three complex control schemes were installed. In all cases the concept was to continually reset the outdoor air (OA) fraction aspirated into the air-handling unit (AHU) as necessary to satisfy ASHRAE Standard 62-1989. A personal computer-based system, independent from the DDC controls, was used to collect data, perform the calculations, and send back new control settings.