The WhisperControl humidity and temperature sensor anticipates condensation and automatically turns on the Panasonic ventilation fan. Unlike traditional sensors, which turn fans on in response to a rapid rise in humid air and therefore could cause them to switch on unnecessarily in certain climate zones, the maker says, this wall-mounted unit detects hot air and humidity based on dew point. The two models—the FV-WCCS1 and the FV-WCCS2—feature a blue LED light and a manual on/off switch and come in white or almond; the FV-WCCS2 also includes a manual on/off light switch. 800.211.7262.