

I got a Technoline WL1030 meter for my room and whenever it reaches 1500 ppm CO2 I open the window until its back down below about 600-700, then I close it to not waste more heat than necessary
Edit: To give some more context, my room is 14 m^2 and about 2.50m high so roughly 35 m^3 of air minus some occupied by furniture call it 30 m^3 maybe. It is a modern house with good insulation and energy retention rating (built to the “Minergie” standard we have here in Switzerland), but without forced air, so not much air is exchanged when the windows are closed. With this I end up roughly having to exchange the air every three hours or so.








Maintenance went so quickly we managed to travel back home in the same day and don’t need to stay at the hotel