Leave home and let the fan run for as long as it needs to remove humidity from the bathroom. This Homewerks bathroom exhaust fan features a dual mode humidity sensor to determine when and how long the fan should run based on the amount of humidity in the room. If less than 60% humidity is detected in the room, the fan will turn off. Use the included wall switch to run the fan in normal mode at full speed at 140 CFM. The choice is yours with the humidity sensing bathroom exhaust fan from Homewerks.