CO2 sensor

The CO₂ sensor includes a set of calibration parameters designed to maintain long-term measurement stability and accuracy in changing environmental conditions. These settings allow users to control when and how automatic calibration is performed, as well as how measurement samples are processed to produce the final CO₂ reading. In addition to automatic adjustments, the sensor also supports manual calibration, which is performed in a known CO₂ concentration (fresh outdoor air or a calibration gas cylinder) to correct measurement offset and ensure high accuracy from the start.

Manual calibration

Manual calibration must be performed in an environment with a known CO₂ concentration and is necessary to reduce measurement offset. Calibration can be done using a reference gas cylinder or in fresh outdoor air. Before starting, place the device in the calibration environment for at least 15 minutes to allow it to stabilize.

Calibrate the sensor before its first use. Without calibration, accuracy is significantly reduced and the measured values may not be reliable.

To perform manual calibration, connect to the sensor using the mobile application and navigate to Settings (three dots in the upper-right corner) → Advanced → Calibration → Manual calibration → CO₂.

Enter the CO₂ concentration present at the calibration site:

• Fresh air calibration: Atmospheric CO₂ averages around 420 ppm. Enter this value into the application. Note that CO₂ concentration varies by location, time of day, and season, so outdoor calibration may not provide maximum accuracy.

• Calibration with a gas cylinder: Enter the exact CO₂ concentration specified for the reference gas used.

Calibration parameters

In addition to manual calibration, several configuration parameters are available to further improve the sensor’s accuracy and tailor its operation to the user’s requirements.

Auto-calibration day	Selects the days of the week when the automatic calibration feature will be active.	Disabled or days from Monday through Sunday.
Auto-calibration time	Sets the time of day (UTC) when auto-calibration should be performed, in minutes from midnight (00h00m).	Range: 00:00 to 23h59m.
Auto-calibration CO2 concentration	The target CO2 concentration (in ppm) the sensor will calibrate towards. Default: 400 ppm (atmospheric CO2).	Range: 0 to 65,535 ppm.
Average samples number	The number of measurement samples used to calculate the final CO2 result.	Range: 1 to 10
Remove min/max Samples	Option to exclude the highest and lowest sampled values when calculating the average.	0: Calculate average using all samples. 1: Remove minimum and maximum samples (requires number of samples to be 3 or more).

Notes on automatic calibration

The CO₂ sensor may experience a gradual reduction in accuracy over time. To maintain optimal performance, the device should automatically recalibrate once per week at the scheduled time (e.g., every Sunday at 2:00 AM). Select a moment when the air in the room is clean - no people present and sufficient ventilation to ensure fresh-air conditions. For most spaces, such as offices or schools, Sunday night is the most suitable choice. In typical scenarios, calibration takes place in fresh air, so the target CO₂ concentration should be set to 420 ppm.