I live in a relatively small apartment (60sqm). Last week I bought CO2 sensors and got totally shocked: after I close the windows, CO2 level is only 30 minutes below recommended 1000ppm and then increases rapidly. If I close the door in the bedroom, CO2 level can reach 4000ppm tomorrow morning.
Apparently my windows don't have micro ventilation (and there is no ventilation system in the apartment built in the 70s).
I have researched on the topic and I understand of course that you just need decent ventilation, but I live in a rental apartment that I will leave in the next 3 years. Therefore, the expensive solutions do not fit.
In my research I stumbled across a solution, a photo of which I attached to my post: simply two plastic parts, you drill the profile, screw the parts on both sides. The inner one can be closed.
This sounds better than not, however I would have questions to ask here on the forum:
1) Is this even a GOOD idea to drill through the profile? I know that in places where it is ventilated in the winter and the moisture from the apartment meets with the cold from outside, mold collects. Now if that would happen INSIDE the profile, it can be quite dramatic: you can't see it and there is enough space for fungus to grow. Or?
2) If you do that, do you drill the outside profile (what is attached to the wall) or the window (where it is inside)?
Basically, I would not drill the windows in a rental apartment.
3000-4000ppm is not a nice value, but can be better eliminated with reasonable shock ventilation than by the minimal passive ventilation, especially in a small apartment.