Plastic windows in the apartment: retrofitting ventilation

Hello! I live in a relatively small apartment (50sqm). Last week I bought CO2 sensors and was totally shocked: after I close the windows, the CO2 level is only below the recommended 1000ppm for the first 30 minutes and then rises quickly. If I close the door in the bedroom, the CO2 level can reach 3000-4000ppm by the next morning. Apparently, my windows do not have micro-ventilation (and in the apartment built in the 70s there is also no ventilation system). I researched the topic and of course I understand that one simply needs proper ventilation, but I live in a rental apartment that I will leave in the next 3 years. Therefore, the expensive solutions do not fit. During my research I came across a solution, a photo of which I attach to my post: simply two plastic parts, you drill the profile, screw the parts on both sides. The inner one can be closed. That sounds better than nothing, but I have questions that I would like to ask here in the forum: 1) Is it even a good idea to drill through the profile? I know that in places where, when ventilating in winter and the moisture from the apartment meets the cold from outside, mold forms. If this happens INSIDE THE PROFILE, it could be quite dramatic: you do not see it and there is enough space for fungi there. Or? 2) If you do that, do you drill the outer profile (which is attached to the wall) or the window (where the pane is inserted)?

Basically, I would not drill into the windows in a rental apartment.

3000-4000ppm is not a good value, but it can be better eliminated with reasonable shock ventilation than through minimal passive ventilation, especially in a small apartment.

Basically, I would not drill into the windows in a rental apartment. 3000-4000ppm is not a good value, but it can be better eliminated with proper shock ventilation than through minimal passive ventilation, especially in a small apartment.

Thanks. I would not have a problem with "drilling in a rental apartment," my landlord is quite nice and would not mind a plastic piece on the window at all. So, this question can be ignored and the situation considered as if it were my own apartment. Shock ventilation does help, but as I mentioned, only very temporarily. Now you have to run between rooms and open windows all day to keep the value below 2000ppm. Do you think such micro-ventilation would not help much?

Yes, it is more of a "guess" than a "know."

In the new building, we also don’t have a ventilation system, but window rebate vents instead. Basically the same thing. However, the rebate vents work through their placement throughout the house and the gentle airflow. At just one window, the air exchange will never be sufficient enough to permanently lower your CO2 concentration.

Just to ask plainly: Sleeping with a tilted window is not an option? We still live in a building from the 1950s with poor windows. When we come home, we ventilate, then also ventilate several times by shock airing over the afternoon/evening.
Since the concentration is significantly higher, it might be possible to speak with the landlord about professionally retrofitting window rebate vents. The financial expense should not be too great.

Well, of course we try to sleep with the window tilted/open if possible. Now in summer that won’t be a problem at all. But already at +5 outside it becomes difficult. With small apartments it’s always worse - you’re basically always next to a window..

Ok, good point. I’ll call a company and see what they recommend.
Thanks!

Drilling a hole is something different from boring through. No idea what the part needs or does, but if you move out of my apartment and leave drill holes in the window profiles without consultation, which are not necessary at specific points to permanently mount a shading on the inside, then that is property damage. And I am also a nice landlord!

I would have no problem, my landlord is quite nice and won’t find a plastic part on the window all that bad.

Ok, good point. I’ll call a company and see what they recommend.

That is the owner’s matter.