Humidity based fan control, HSW, adds intelligent moisture detection to any fan or ventilation system. HSW senses condensation levels in the air, turns on the fan or ventilation system and runs it until the room is back to a safe moisture level. HSW has adjustable timer settings for manual time use and adjustable condensation for sensitivity. The capability to adjust the sensitivity level on HSW enables the end user to truly tailor their fan or ventilation system to any environment regardless of room size, climate or season.