I got a CO2 sensor too, cheap but not entry level (about €125). It also does TVOC, PM1.0 and PM2.5.
One reason was I "balloon" sealed an unused chimney (old house) for the winter, that was the main driver of ventilation (and drafts).
If I don't crack a window, me, desk-working in a ~85m³ room pushes the reported CO2 from 400 to nearly 800 ppm by lunchtime, though the device is close to (not on) my desk which probably skews it a bit. I don't have any data to compare though, I might remove the balloon when weather improves next month to see.
There's also a gas hob(!) in the adjacent kitchen, the other VOC/PM readings are elevated for as long as 12 hours (depending on how badly my cooking went :),
even with a hob extractor fan running and permanently open intake vents.
The speed of CO2 increase and persistence of the effects of cooking were both a surprise to me.
If I don't crack a window, me, desk-working in a ~85m³ room pushes the reported CO2 from 400 to nearly 800 ppm by lunchtime, though the device is close to (not on) my desk which probably skews it a bit. I don't have any data to compare though, I might remove the balloon when weather improves next month to see.
There's also a gas hob(!) in the adjacent kitchen, the other VOC/PM readings are elevated for as long as 12 hours (depending on how badly my cooking went :), even with a hob extractor fan running and permanently open intake vents.
The speed of CO2 increase and persistence of the effects of cooking were both a surprise to me.