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I'm wanting a Co2 monitor that works without cloud and looked at some of the sensors available.

Does the sensor in your project need to be taken outside to calibrate?

I stopped when I realised many sensors (like scd30/40) need this making it very impractical.. Has to be done once while powered on the whole time in a 7 day period.

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I don’t enable automatic calibration on my SCD30 because the algorithm basically assumes that the lowest ppm in the last 7 days is 400ppm and baselines to that. I just took mine outside once, set that to 400ppm and haven’t recalibrated it since. The drift on the sensor is supposed to be very low.

I think pretty much all indoor air quality monitors with NDIR sensors have by default an automatic baseline calibration. Our kicks in every 7 days. So you should somehow reach ambient CO2 levels once a week to have it properly calibrated.

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