Does anyone know of a cheap IoT type sensor for CO2? It can be any type, even RasberryPi or Arduino based. I'm not interested in sensors without connectivity options.
About the levels, I'm working on an IoT project and I've seen data from a public school that has heating with radiators (so no real ventilation). One classroom with the sensor would routinely rise above 1000 ppm, with peaks over 3000ppm. Then you'd observe a sudden drop in CO2 level and temperature as they would open up a window. It's insane how high it can get especially if the building lacks proper ventilation.