ᐅ Ventilation System CO₂ Levels [ppm] in Your Rooms

Hello everyone,

to all controlled residential ventilation system owners: Have you ever measured the CO₂ levels in ppm in your ventilated rooms out of curiosity?

According to information online, the values should be below 1000 ppm. About 400 ppm is the fresh outdoor air level. Normally, I have around 600 ppm – 700 ppm when no one is in the room. Of course, this value increases with the number of people present.

What I’ve noticed is that in our bedroom, the level rises above 1000 ppm during the night, which is not ideal. I originally thought that was exactly why I installed a controlled residential ventilation system – to always have fresh air.

So, I would be interested in comparison values from you, if you have any.

Maybe something is wrong with the system.

Older technical books mention 300 ppm CO2 in the atmosphere. However, a few years ago, the average CO2 concentration was measured at 400 ppm. My measuring device also consistently shows baseline values around 400 ppm (i.e., empty house, well ventilated).

In an occupied/used house, the normal value here is around 500 ppm. In the bedroom (two people), I recorded data twice with the device. One time it averaged 600 ppm, the other 700 ppm, with maximum peaks around 800 ppm each time.

Values over 1000 ppm are only reached during parties or with many guests. Usually, I then increase ventilation, which helps somewhat (700 ... 800 ... 900 ppm, depending on the number of guests, of course), and eventually, a window has to be opened.

How much does your controlled residential ventilation system reduce airflow at night?
Does the overflow work properly when the door is closed?

There is no night setback mode, only an "Auto" operating mode, which is apparently controlled by the temperature. I didn’t fully understand this during startup. Typically, we run a "reduced ventilation" mode.

We installed "innoperform overflow seals." They work well.

Hello, nice to see that someone can say something about this topic.
The mechanical ventilation system is a Vallox, and the installer had set it to a night setback mode. However, I removed this, and now the ventilation runs at the same level day and night. Still, at night we exceed 1000 ppm.

Regarding air transfer, I can’t really say much. No special measures have been taken, except that the bottom of the door has a gap where air can actually circulate.

So, do you think that 1000 ppm is definitely too high? I mean, when I compare these values to those from Bieber0815.

The state of Lower Saxony provides a CO2 calculator, available at weh weh weh dot co2-modell dot nlga dot Niedersachsen dot de. You can experiment with it a bit.

There is also some information to help interpret the numbers (1000 ppm is not yet a disaster).

Why not share the volume of your house and the air exchange rate you have set?