With its built-in and/or external VOC (Volatile Organic Compounds) sensor, the thermostat measures the room air quality and shows the air quality status symbol on the local idle screen. In the mobile app, the status is indicated by text.

If no external VOC sensor is connected or if the input value of the external sensor is invalid, only the built-in sensor is used to provide values for the thermostat. If the external sensor is connected and can provide valid values with the built-in sensor, the thermostat displays the higher value of the built-in and external sensors.

Symbol on the local idle screen

Text in the mobile app


VOC level
[% of the output range]


The room air quality is good



The room air quality is average

50% ~ 80%


The room air quality is poor


There is a default air quality setpoint for each operating mode in a schedule. It is adjustable under “Advanced Settings” > “Optimization”. If the actual VOC level is 10% higher than the default setpoint for the current operating mode, the ventilation function is activated to force air circulation.

To ensure that the room air quality is measured accurately when the room is closed for a long time, it is recommended to circulate air such as opening a window.