CO2 sensor
Efento CO2 sensor requires calibration to properly measure CO2 concentration. The device supports two types of calibration: manual (on demand) and automatic. Manual calibration should always be performed before installing the device. Automatic calibration is performed once a week, at the time defined by the user in order to adjust the sensor's sensitivity.
Manual calibration
Manual calibration is performed in a known CO2 concentration and is required to reduce the measurements offset. Calibration can be either performed using a gas cylinder with a known CO2 concentration or in the fresh air (outdoor). Before performing the calibration leave the device in a place with known CO2 concentration for at least 15 minutes.
Make sure to calibrate the sensor before using it! Without the calibration the sensor’s accuracy is low and the measurements taken by the sensor are not reliable!
In order to calibrate the sensor connect to it with Android application -> settings (three dots in the upper right corner) -> “Advanced” -> ”Calibration” -> “Manual calibration” -> “Select a channel”. Key in the concentration of the CO2 in the place where the sensor is located:
Fresh air calibration- the average concentration of the CO2 in the atmosphere is 420 ppm. Key in that value in the application. Please note that the concentration of the CO2 varies between places, time of the day and time of the year. Therefore the calibration in the clean air does not guarantee the best possible accuracy
Calibration with a gas cylinder - in the application key in the concentration of the gas in the reference cylinder used for the calibration
Automatic calibration
Automatic calibration is performed by the sensor once a week at the scheduled time (e.g. every Sunday at 2 AM). Make sure to pick the date when the air in the room where the sensor is located is clean (there are no people in the room, there was enough time to ventilate the room). For the majority of the use cases (office, schools, etc.) the best time for the automatic calibration is Sunday night. In order to change the settings of the automatic calibration use the mobile application. Connect to the sensor -> settings (three dots in the upper right corner -> “Advanced” -> ”Calibration” -> “Calibration parameters” -> “Select a channel” -> “Automatic”. Set the time, when the device should auto calibrate and the expected CO2 concentration at that time (for majority of cases the auto calibration will be performed in the fresh air, so the expected concentration should be set to 420 ppm).
Sampling settings
At each measurement, the device can take a few samples and calculate the average value in order to increase the measurement accuracy. This allows to reduce the noise but decreases the battery life time. Users can decide how many samples should be taken at each measurement and how the samples should be proceeded. It is possible to set the following parameters:
Number of samples - how many samples are taken at each measurement and are used to compute the average value
Remove min / max samples - if this option is selected, the device will remove the lowest and the highest sample and calculate the average out of the remaining samples. Example: device is set to take four samples at each measurement. Measured CO2 concentrations: 450, 504, 508, 550. If the min and max values are removed, the average will be computed from two samples - 504 and 508 and the device will return the measurement value: 506 ppm.
Sampling settings can be changed with the mobile application. Connect to the sensor -> settings (three dots in the upper right corner -> “Advanced” -> ”Calibration” -> “Calibration parameters” -> “Select a channel” -> “Manual”.
Important! Increasing the number of samples taken at each measurement decreases the battery life time!
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