Air exchange rates and air quality - understanding

Hello forum!

I wanted to talk with you about air exchange rates and generally also about your air quality. Especially now in winter, we rely 99% on our ventilation system and only rarely open the windows (e.g. after cooking).

Our system is a Zehnder Q350 and normally runs at level 1. According to the app, this corresponds to about 160 m3 per hour.

Now I have read that a person needs about 30 m3 per hour. So if two people are in a room, they need 60 m3 of fresh air. But the system delivers only 160 m3 distributed over the whole house. That means the air must slowly get worse, right?

I can also measure exactly this phenomenon. I bought a CO2 meter from Amazon and it shows me the ppm.

It has 470 ppm in the morning in every room, that is the quality of the atmosphere. After a few hours the value rises to about 850 ppm. But then it remains relatively constant, because we probably also leave the room.

If I switch the ventilation system to level 2 = about 220 m3 per hour, the value drops slightly again.

How do you handle this, what capacity do you use and have you had the same experiences?

Best regards

CO2 and VOC sensors in the system and/or rooms then regulate themselves continuously. Then you never have to touch them again and the air is always exchanged in the necessary amounts.

In the morning, there are 470 ppm in every room, that is the quality of the atmosphere. After a few hours, the value rises to about 850 ppm. But then it remains relatively constant because we probably leave the room as well.

I don't understand. If you are at home at night, the quality is good. Then it gets worse even though you are out?

Hi,

with us, the E350 also runs continuously on level 1 (160m²) except usually in the evenings after cooking/eating for 2-3 hours on level 2 (210m²). We are very picky when it comes to fresh air and are very satisfied, although I have not yet tested with a CO2 meter.

We were at friends' on Saturday in a new building without a ventilation system, and right at the front door you are already hit by a wave of stale, stuffy, humid-warm air...

470 ppm has it in every room in the morning, that is the quality of the atmosphere. After a few hours the value rises to about 850 ppm. Then it remains relatively constant because we probably also leave the room.

Do you sleep away from home at night or how is that to be understood?

I only meant that I don't know if it would continue to rise because, for example, after 3 hours we leave the house or change the room. Then it goes down again to 470 ppm.

CO2 and VOC sensors in the system and/or rooms, and then it adjusts itself continuously. Then you never have to touch it again, and the air is always exchanged in the necessary amounts.

With that, you won’t catch peaks as described (two people in a confined space over hours). Since the rooms cannot be controlled individually.
The result would then only be that the system would have to run continuously at an increased level.

On the other hand, 850ppm is not a dramatic value. Maybe it’s not even a great idea to want to measure that at all, as there is no comparison.

I am very satisfied with our controlled residential ventilation. I vacuum the central filters once a month, the decentralized ones in the exhaust … there I am lazier. Runs well so far. Also a Q350 with enthalpy, running at 185-190m³.