[saurik]

I own an Awair unit, and as far as I can tell it attempts to calibrate itself based on outside atmosphere having 400 ppm... but that value is constantly going up and is now like 415, so I figure my unit must be at least a few percent off.

[b112]

I may be misunderstanding, but if you claim outside is 415 and that's that, it's wildly inaccurate.

Where you live, time of day, lay of land, all matters.

Winter (no trees or vegetation with photosynthesis), and there is naturally more local CO2.

Live deep in the country, in a forest, in the summer, when trees have loads of water and are at max output? Less CO2.

At night, more CO2, for all those trees, that greenery, is breathing and exhaling CO2, with no sun for photosynthesis.

It's variable, not static.

[bumbledraven]

Just how "wildly" inaccurate are we talking about? What should the outside CO2 readings actually look like under those conditions?

[b112]

As an example, close to a busy road, you may as well double the number in parent. Calibration by outside air is strange.

[bumbledraven]

Close to a busy road, sure.