The patent pending Strobic Air® Smart Fan™ maintains safe ventilation levels while minimizing facility energy costs and carbon footprint. It is the latest improvement to the highly successful TriStack® mixed flow exhaust fan line for “safety critical” applications such as laboratory fume hood exhaust and ventilation for specialized care environments like airborne infection isolation rooms. The Smart Fan™, which uses a combination of sensors and controls to determine the flow required for safe operation, continually adjusts fan speed to produce optimal flow. In multi-fan applications, fans will automatically turn on or off as required. Additionally, the Smart Fan™ can sense a fan failure and turn on a “stand by” fan to maintain safe exhaust operations. Other advantages of Tri-Stack™ systems include low profile design, low noise levels and vibration free operation. Tri-Stack™ systems are also virtually maintenance-free, offering significant cost savings with regard to maintenance labor, while eliminating the need for rooftop penthouses and expensive vibration prevention hardware. Direct drive motors provide up to 200,000 hour lifetimes, eliminating the need to replace belts, pulleys, or other limited life components. Tri-Stack™ systems should be considered wherever issues of exhaust pollution, odor control, re-entrainment, aesthetics and energy savings are important.