Abstract: The flow of air through a fume hood is optimized by producing a bi-stable vortex within the vortex chamber of the fume hood regardless of sash movement. A bi-stable fume hood optimizes capture face velocity to minimize backflow of fume laden air through the hood sash opening. This bi-stable vortex fume hood reduces the energy consumption up to sixty percent versus the present day mono-stable vortex fume hoods. The bi-stable vortex fume hood utilizes a vortex pressure control system to reposition top, center, and bottom slot openings of a baffle in the hood. This baffle moves the bi-stable vortex away from the fact when the sash is fully opened and creates a clearing action near the work surface as the sash is closed. The fume hood's airfoil is placed inside the fume hood chamber and the airfoil has multiple entry pattern, one of which turns the vortex up and away from the open sash window. The other creates flow which washes the work surface of the hood.