Window configurations and control strategies for natural ventilation were analyzed by modeling the building in a separate whole-building energy analysis tool to enable explicit modeling of the thermal effects of natural ventilation and thermal mass effects, which the main energy modeling software cannot do. The natural ventilation modeling was performed without including mechanical systems, so results represent passive conditioning. Then, on days when the as-designed window arrangement and natural ventilation controls yield temperatures that do not exceed 78°F or fall below 69ºF, the thermostat cooling set point was set to 100ºF (turned off) in the main office wing spaces. Preliminary modeling showed that night purging to cool the office spaces would be a promising strategy to save energy. Natural ventilation modeling made an impact on the preliminary building design in the form of low-level motorized windows being added to enhance stack effect ventilation and allow better night cooling.