[yoshuaw]

Worse specs? Sure. Worse value? I don't think so. Worse accuracy? Perhaps not either.

A price of 30 EUR makes this sensor really easy to pick up. For the same price as one Aranet (~180 EUR) the typical household can place a sensor in every room of the house. Which provides far more accurate readings for the whole house than just one high-end sensor in one room.

[freefaler]

I have one IKEA Apstuga on my desk, sitting right next to a good CO2 monitor. Since Apstuga uses worse approach (heat) rather than light as the good sensors, it diviates around +/- 100 ppm. For example the correct CO2 is 610 ppm and IKEA's sensor shows 552 ppm with is reasonably close. So the trend will be correct and the values will not be.

But when it goes over the safe limit it should be enough to decide to ventilate.