[Yajirobe]

I have a CO2 monitor and I don't understand one thing - it seems that CO2 increases more quickly during summer than during winter. If I close my windows it takes longer to reach 1000 ppm during winter than it does during the summer.

I didn't gather concrete data on this but this is just what I eyeballed over the last few years. Does anyone know why could this be the case?

[pavlus]

Cold air is more dense, than hot air. In winter the difference between the room air temperature and outdoor air temperature is much bigger, so the density difference is much bigger, making Archimedes force stronger and the airflow stronger as well.

BTW, that's also how stove pipes work - vertical column of air hotter than surrounding accelerates well and creates a strong airflow feeding the fuel. But if the pipe is thermally conductive, that air will cool down and won't flow, for hydrocarbon fuels it can also condensate water, that could extinguish fire underneath it. So, pipes are made insulated enough for strong flow.

[bad_username]

The speed of air exchange through openings in your room (windows, gaps etc) is proportional to the difference of temperature between your room and outside. The more different the temperatures are, the more intensive convection is, and convection is very effective at moving/exchanging air. In summer the difference in temperatures of your room and the outdoor space is much smaller than in winter, which subdues convection, and the stale air tends to stay.

[hoppyhoppy2]

Do you have a forced-air heating system?