arious economizer damper control strategies were studies to show their effects on fan performance and outdoor air control. The strategies were evaluated by simulations for a typical existing HVAC system. Several factors were considered such as the building locations, system characteristics, minimum air flow rate, economizer control, and supply air temperature control. The results show that the way of the economizer dampers been controlled has a significant effect on fan performance and its energy use. The split control strategy if properly implemented can provide fan energy saving in the range of 5–30% with an adequate outdoor air control. The saving is not much sensitive to the building locations, supply air temperature, or economizer strategies, but much related to the minimum air flow rate required and damper and duct characteristics. The effect of the locations is mainly related to the number of hours when the dampers are in free cooling mode. As this number increases, the saving obtained will increase. The split control strategy needs no or very small initial cost mostly related to software change and the possibility of adding extra actuators.