Light sensorWhen the light sensor is enabled, Svara senses when someone is in the room and then activates. This sophisticated light sensor is triggered by light movement and shadows. It is possible to set a delayed start so the fan is not triggered during quick night time bathroom visits. The light sensor can also distinguish between headlight flashes from cars and room occupancy, so it is not triggered by passing cars, avoiding nuisance running. The sensitivity of the light sensor can be adjusted via the App. Overrun Timer The light sensor provides an overrun timer but only requires a live and neutral. This means that if you have a basic on/off fan installed in your home, you can upgrade without the need of an expensive re-wire. Humidistat Svara features a humidistat which reacts to sharp changes in humidity, for instance when someone is taking a shower. When set to continuous running, once the humidity sensor is activated, the fan runs at 30l/s until humidity returns to normal levels, then the fan powers down to 10l/s. Ambient humidity changes will not trigger the humidistat. It is possible to change the sensitivity of the humidity sensor via the App. In summary, we highly recommend this fan! The Svara is one of the most powerful, most energy efficient and quietest four inch Axial fans available from in the UK and if you love your gadgets, this is the fan for you. Boost: 110m3/hr | 30L/s | 20dB(A) High Trickle: 68m3/hr |19L/s | 17dB(A) Low Trickle: 36m3/hr | 10L/s | 17dB(A)