A portable enclosure is configured to mix room air with a controlled amount of exterior air via one or more flexible conduits disposed between the enclosure and an exterior window. At least one flexible conduit is connected to a barrier structure which is designed for sealable placement within the window. One or more mixing dampers are employed to control the amount of exterior air supplied to the enclosure. An air moving device delivers exterior air in controlled amounts to the enclosure which is designed to be movable so that a more desirable (fresher, cooler, and more contaminant free) stream of air is deliverable to the personal space of an occupant to satisfy ventilation and temperature requirements.