Carbon Dioxide Monitor | CO2 Monitor | Carbon Dioxide Detector
How to read the number, and which monitor suits which room
A carbon dioxide monitor answers one question: is fresh air getting into this room. You cannot answer that by standing in the room, which is the entire reason these exist.
This page covers what the reading means, where to put the monitor, and the difference between the two we stock.
What the number means
Carbon dioxide indoors is mostly a headcount problem. People breathe it out constantly. If fresh air is not replacing what is in the room, the level rises through the day, and how fast it rises tracks how little air is coming in.
The useful reference points:
- 400 to 420 ppm is roughly outdoor air. That is your floor, and no indoor room will read below it.
- Under 800 ppm generally means air is genuinely moving through the space.
- 1000 to 1500 ppm and above means the room is largely recycling the air already in it.
Those are ventilation benchmarks. They are not health thresholds, and a monitor is not telling you the air is safe or unsafe. It is telling you how well the room breathes.
What a CO2 monitor does not do
It measures carbon dioxide. It does not detect carbon monoxide, which is a completely different gas and needs its own alarm. If you have any fuel burning appliance, fit a proper CO alarm and do not treat a CO2 monitor as a substitute for one. The names are similar and the consequences of confusing them are not.
It also does not measure smoke, particulates such as PM2.5, or volatile organic compounds. Keep your smoke alarms.
Where to put it
Head height, away from a window, away from a doorway, and not directly in front of somebody's face.
A monitor on a windowsill measures the outside air coming in. It reads reassuringly low and tells you nothing about the room. A monitor someone is breathing onto spikes and tells you nothing either.
The two minute test worth doing first
Note the reading. Open a window. Watch what happens.
Some rooms drop hundreds of ppm in a couple of minutes, which means ventilation is fine and the room simply needed it. Other rooms barely move, which tells you the airflow is not where you assumed and that no amount of monitoring will fix it on its own.
That single test is worth more than any absolute reading, because it tells you whether the fix you were planning will actually work in that particular room.
One monitor per ventilated space
Buildings are not uniform. A room with its own door, windows and vents behaves differently from the one next to it, so a single monitor describes its own room and little else.
If you are covering a school or an office floor, count separately ventilated spaces rather than floor area. Two rooms sharing one open plan airflow can share a monitor. Two closed rooms cannot.
Which of the two to buy
The measurements are identical. The difference is who needs to read it.
The compact CO2 Meter is palm sized at 108 g, reads 400 to 5000 ppm alongside temperature and humidity, refreshes every second, and has an audible alarm that triggers when the level climbs. It suits one person checking several rooms, or a single desk or bedroom.
The Jumbo CO2 Monitor is the wall mounted version with a large format screen built to be read from across a room. Buy that one when a room full of people needs to see the number, because a reading on a wall gets acted on and a reading on a desk gets ignored.
Using it in a classroom or an office
These are the rooms where a monitor changes behaviour rather than just producing data. A full classroom climbs quickly, and the number gives whoever is nearest the window a reason to open it that does not involve an argument about whether it feels stuffy.
Set the alarm on the portable model if nobody is going to be watching a screen. For a permanent installation, the wall mounted display does the job without anyone remembering to check.
Delivery is free on orders over €50 and otherwise €22, arriving in 5 to 7 days after a 24 to 48 hour handling time. For several rooms or a whole site, ask on the wholesale quote page.