Relative humidity

The sensor acquires relative humidity via a digital capacitive relative humidity sensor with bandgap temperature sensor.

The electronic measuring circuit converts the sensor element’s humidity signal to a wireless digital signal (0...10000), corresponding to a relative humidity range of 0...100 %.


The sensor acquires the temperature via a digital humidity and temperature sensor.

The temperature signal from sensing element is converted to wireless digital signal (0...10000), corresponding to a temperature range of 0...50 °C.

CO2 concentration

The SymaroTM air quality sensor acquires the CO2 concentration by infrared absorption measurement (NDIR) with automatic baseline calibration.

The resulting wireless digital output signal (0...5000) is proportional to the CO2 content of the ambient air, corresponding to a CO2 concentration range of 0...5000 ppm.

Automatic baseline calibration (ABC) of CO2 measurement

The ABC function for CO2 measurement baseline is 400 ppm (fresh air). The sensor can detect a room that is regularly unoccupied but linked to the outdoor air exchange, and perform automatic calibration periodically if ABC is activated.

ABC is activated at 180 h interval. ABC can be disabled if not needed (i.e. no exchange of outdoor air).