A CO2 meter measures the amount of carbon dioxide in the air, expressed in ppm (parts per million). Most affordable and accurate CO2 meters use an NDIR sensor for this purpose, which stands for non-dispersive infrared.
The technology behind a CO2 meter
An NDIR sensor sends infrared light through a small chamber where air flows through. CO2 molecules absorb a specific wavelength of that light. The more light is absorbed, the more CO2 is present in that air. The sensor converts that measurement into a ppm value, which you see on the meter's display.
What the meter does and does not measure
A CO2 meter measures carbon dioxide exclusively, and says nothing about particulate matter, pollen, volatile organic compounds (VOCs), or humidity, unless the device combines multiple sensors. Some models also measure temperature and relative humidity, but these are separate sensors in the same device, not something derived from the CO2 measurement itself.
What to look for in a CO2 meter
A few practical points to keep in mind:
- Sensor type: NDIR sensors are generally more accurate and stable than cheaper alternatives such as electrochemical sensors.
- Placement: place the meter at breathing height, not directly next to a window, door, or ventilation grille, for a representative measurement.
- Calibration: some meters calibrate themselves automatically by periodically comparing with outdoor air; check if that applies to your model.
- Response time: a good meter shows a noticeable change within a few minutes after opening a window.
Combining a CO2 meter with ventilation
A CO2 meter itself does not lower anything, it only signals when the air in a room has been "used" for too long. The solution remains the same: ventilating with fresh outdoor air. Dynter does not sell CO2 meters itself, but for other aspects of your indoor climate, such as too much moisture or particulate matter, we do offer suitable products. Think of a dehumidifier for structurally damp rooms, or an air purifier for dust and allergens, as a supplement to good ventilation.
In short: a CO2 meter is a handy tool to see when ventilation is needed, but it does not replace ventilation itself. See on dynter.eu which products suit other aspects of a healthy indoor climate, such as the dehumidifier and air purifier.