[HenrikB]

Yes, the amount of CO2 each person produces is noticable, especially in such a small room.

If possible, keeping a bedroom window a bit open makes a noticable difference. Avoid closing bedroom door too.

Similarly, if you work from home, make sure to create a draft once in a while.

We got an Aranet4 CO2/humidity/temperature sensor mostly out of curiosity two months ago. Outdoors it's ~430 ppm CO2. 500-1000 ppm indoors is considered okay (according to the defaults), 1000-1400 ppm high, and >1400 ppm bad.

It's amazing how you don't notice how it slowly creeps up to 900-1000 and beyond. Without the device I would notice, except that I'd slowly get tired. I'd probably also drink more coffee. The device helps you see what's going on and how bad it is. Creating a big draft for 5 minutes clears everything out.

Also, you can definitely see from the historical data when one goes to bed in a ~12 m2 bedroom and then an hour or so later the second person goes to bed. Same if one gets up before the other. Definitely good evidence that keeping a window open is a good thing (if you got clean air outside)

[qlm]

I've never been sure how to reconcile this with advice about insulation.

It's currently really cold where I live, and I am trying to limit outside air coming in as much as possible. This then leads to the air having uncomfortably high levels of CO2, as confirmed using an air quality sensor.

[Atheros]

It can't be reconciled. Which is why there are going to be more posts about air exchangers on HN in the future.

[lm28469]

> with advice about insulation.

Good insulation only works with good ventilation anyways, the goal of insulation isn't to make an house completely airtight

Look into these things: https://en.wikipedia.org/wiki/Heat_recovery_ventilation

[JohnBooty]

Agree. I got a CO2 monitor for my office a few ago and it was a real eye-opener.

It has made me notice "stuffy" air more keenly and helps me avoid it. If I'm stuck in a physical meeting room at work I take lots of walks and breaks. etc.

I haven't tried the CO2 sensor in the bedroom. We like to sleep with fans on and the bedroom door open, which I suspect helps somewhat (depending on how drafty one's house is overall) although is obviously not as effective as having a window open.