Maritime sounds humid. Is that the case? There are probably some papers written about this. Your scheme brings to mind "Earth Tubes". It seems to me that you might like to choose between the earth-moderated and ambient air depending on the ambient temperature and what you need to do with it to be comfortable.

Hi, Thanks for the comment. No, in my case the climate is quite dry, but some maritime climates are humid. A maritime climate means one that is moderated by the sea temperature, giving a lot less seasonal variation than the opposite continental climate, where the seasonal variation in land temperature has a lot more effect.