User Manual


In principle, the CO2 concentration in a room is homogeneous. However, due to partition walls, open windows, large rooms, etc., the CO2 value can be different in different places within the same room. It therefore makes sense to take measurements in several places in larger rooms (> 50 m²) or in rooms with open windows or doors.

  • Place the meter in the used part of the room as much as possible. 
  • Place the sensor on a table or cabinet, against the wall or in the middle of the room.
  • Set the sensor not next to a door or window or inlet of the ventilation system.
  • Make sure the meter is in a safe place so that it does not fall over or be spilled on.
  • Do not breathe near the sensor; this may affect the measurement. Do not place the meter directly next to a person, keep a distance of 1.5 m. 


A total of 4 holes are provided for hanging the sensor. Use at least 2 holes to hang up the CO2 meter correctly.

A nail is also a possibility to hang the sensor. If you use only one nail, the sensor will probably hang at an angle. In itself not a problem, but visually not so nice. Make sure that the sensor cannot fall off the nail!

Double-sided adhesive tape may also be used. Make sure, however, that the sensor cannot come loose. A fall to the ground can damage the sensor irreparably.

You can also use an adhesive magnet to attach the sensor to a magnetic surface. Again, make sure that the sensor cannot fall on the ground.

Place the sensor (without housing) not against a metal (or conductive) background so that the pins do not create a short circuit. Even better is to print your own enclosure, the 3D .STL files can be found at here.


The CO2 meter needs energy to work. This can be supplied through the USB-C connector of the display board. A standard USB adapter can be used for this. If you use a normal USB adapter then you must ensure that you have a USB-A to USB-C cable (the CO2 sensor has a USB-C connector). You can also use a USB-C adapter. In that case you will need a USB-C to USB-C cable.

You can also supply energy to the CO2 meter via a free USB port on your computer/laptop or even a beamer (digiboard). Make sure that this USB interface is switched on all the time! If you switch off your computer/laptop in the evening, this is not a good solution as the sensor needs to be on 24 hours a day to measure correctly (see also FAQ).

If you don't have a good USB adapter or cable lying around, you can always order it in our webshop.


The CO2 meter is not supplied in a housing (most electronic products are protected by a plastic housing). However, in terms of safety, there are few or no problems. The entire sensor operates at 5V which is a very safe voltage. The CO2 sensor part itself is also perfectly sealed. The print has no sharp edges.

Electronic components can be sensitive, so we recommend that the CO2 meter in such a way that children do not need to touch it. This avoids broken USB-C connectors, scratches on the display or bad measurement results.

Make sure you have a reliable USB adapter and USB cable (you can buy them from our webshop).

If the sensor is used with small children or children with learning disabilities or behavioural problems, it is recommended that the sensor (as well as the USB adapter and cable!) be installed out of reach of these children.

First use

During the first 24 hours the measurements may not be reliable. Make sure you ventilate the room sufficiently during this period and ignore the value that appears on the CO2 sensor display. Leave the sensor on continuously.

In exceptional cases, it is possible that the sensor indicates an incorrect value for a longer period of time (up to a maximum of 7 days). When you enter the classroom in the morning, the sensor should give a value between 400 and 550 (usually even less than 500). If this is not the case, replace the CO2 meter for a few days in the dry outside air (continuously switched on!). After about 4 days you can take the sensor back inside and it should work normally.

Daily use

In normal operation, the CO2 sensor displays the CO2 concentration in ppm. The display will indicate the severity of the CO2 level by colour.

420 789 1010
  • Green: CO2 value is sufficiently low.
  • Yellow: CO2 value is high but still acceptable. Take action to reduce the level if necessary.
  • Red: CO2 concentration is too high! Ventilate the room as quickly as possible and, if necessary, leave the room temporarily.

By default, the threshold values are set as follows:

  • Green: CO2 value is lower than 700 ppm
  • Yellow: CO2 value is between 700 and 800 ppm.
  • red: CO2 value is higher than 800 ppm.

When you ventilate the room, it is possible that you will see the number on the CO2 sensor (CO2 level in ppm) continue to rise. This is normal. There is no need to panic. But do continue to follow it and take corrective action if the CO2 level does not drop sufficiently and returns to the green zone.

Ensure that there is at least once a week very good ventilation is so that the sensor can use the outside air level (usually between 400 and 500 ppm) for the ABC calibration process.

Adjusting settings

You can change the settings via Wi-Fi. Just follow these steps:

  • Press the button to the right of the USB connector (if Demo appears on the screen, you have pressed the wrong button).
  • A message will appear on the display asking you to connect to the Wi-Fi network with name "operame-xxxx" or "controlco2-xxxxx".
  • Connect your smartphone (or computer) to this Wi-Fi network.
  • Wait a moment and you will see a portal where you can adjust the settings.
  • Once you have adjusted the setting, press Save. (Save) (bottom right) and then click Restart (restart device) (top left).

If you do not see a portal appear after 10 seconds, open your web browser on your smartphone and surf to

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