> At baseline, the levels in my apartment were already dancing around 1,200 (ppm)...(marketing numbers)... I flung open a window... Two hours laterthe Aranet still hadn’t budged below 1,000 ppm
Something is very wrong here if your house/apartment is getting cold and a CO2 meter near a window is not dropping. Author should take it outside and check to see a number <500ppm (probably closer to 420). Device could be broken or poorly calibrated. It happens.
As for air flow in the apartment, this can often still be quite a mystery and weird to solve. My bedroom would constantly be above 800ppm, and above 600ppm with an open window. The solution? Opening a window on the other side of the apartment (need to pay very careful attention to paths that air can travel). A cracked window in my bedroom, a cracked window on the other side of the apartment, and boom, my bedroom is constantly near 400ppm (near ambient levels in my area).
But opening any other window in the apartment would not lead to this solution. Houses weren't designed with air flow in mind. Lots of hard corners can make it difficult to move air around (eddy currents are a pain). I do sleep better and there's probably some cognitive increase (I don't buy the 15-50%), but one of the larger benefits is the temperature is more stable (stable temperature is a good indication of good air flow btw). So I do encourage others to try this problem solving, but just want to note that the solutions are non-obvious. If you're having these issues, brute force the solution. You'll over think it (I did) but you're too clever by half[0]. You're working with a chaotic system and even the state of a door that doesn't seem in the flow path might affect the flow. If it isn't working, try dumb things and also use temperature as an indicator in addition to CO2. You can always use a fan too (draw air in on the opposite side of the house).