6 tips on where (not) to place an Indoor Air Quality Sensor

1. Not where someone is directly breathing on it

If you place the sensor directly next to a table or right next to a bed (or above it), breathing can adversely affect the sensor’s measurements, reporting higher values than actually exist. This is because a person exhales (in addition to other pollutants) approximately 100 times the concentration of carbon dioxide than is found in outdoor air! Outdoor concentrations are usually below 450 ppm, while a person exhales air that contains 40,000 to 50,000 ppm!

2. How high above the ground?

The best placement is 1.2 – 1.8 meters above the ground, about the height of light switches. When it comes to carbon dioxide itself, although it is heavier than air, it typically mixes well in normal spaces due to human movement and natural infiltration or ventilation, so the height of the sensor is not that critical. In a very tight bedroom, it is good to place it at head height.

3. Don’t hide it

In the corner of a room, air circulation is poor, and the sensor may not detect increased levels of air pollution. The same goes for behind furniture, where dust can accumulate on the sensor, increasing the risk of filter clogging.

4. Not directly by windows or doors

Near windows (whether open or closed) and doors – especially entrance doors – outside air can affect the sensor due to possible leaks. This can falsely lower the measured values, and the room may not be adequately ventilated based on the distorted information from the sensor.

5. Watch out for temperature and humidity

It is not advisable to place the sensor in areas where humidity or temperature changes (very) rapidly. Direct contact with liquids would be particularly detrimental to the sensor – therefore, place the sensor where it cannot be splashed with water or chemicals.

6. Pay attention to the placement of ventilation system outlets

Ventilation system outlets can affect air quality measurements, so it is advisable to place the sensor at a sufficient distance from them.

➡️ The placement of the sensor must always be tailored to the specific space; in addition to the points mentioned above, care should also be taken regarding ventilation outlets. The best solution is, of course, to consult an expert in the design of air handling systems.