[bjackman]

That's interesting coz I found the opposite, at my place to keep the level below 1k I usually have to open a window in the room I'm in, or use a fan.

I live on a noisy street so I don't usually want to do that, if I open a window at the back and keep internal doors open it will stay reasonable but significantly elevated.

So yeah I think the lesson here is you probably need to buy a sensor, different homes are gonna differ.

My home is quite small (probably 80m²) and has literally zero ventilation built in (even in the bathroom!). I live in Switzerland where it's traditional to actively ventilate your home twice a day. But that doesn't do anything for CO2. Also it's such a fucking waste of time lol. Looking forward to moving into a modern building.

[Gigachad]

I think it’s just quite windy where I am combined with a not particularly airtight building so opening the window just a crack results in a lot of air blowing in

[bjackman]

Yeah I was thinking airtightness might be the difference. My flat seems to be bizarrely hermetic (when you turn on the kitchen extractor fan, it struggles if you don't have a window open somewhere).

So maybe a few leaky cracks are enough that when you open a window you get a bit of a through-draft.