| Modern building codes do carefully consider ventilation, but I think a lot of knowledge and tradecraft have been lost. If you're lucky and live in an older house of the correct design from just before A/C, (most of the oldest two-story single family homes in Berkeley, FWIW) you might notice that some of the internal walls stay well below room temperature during the summer. The buildings typically have pier and beam foundations, and the cooling walls have passive draft ways that pull cool air over the ground under the house and up against those walls. This is great in the summer, but not so much in the winter. I don't know how they use convection to pull cold air up, or how they prevent moldy foundation dirt air from permeating the house. I've heard there are some pretty clever designs, but (of course) they're hidden behind walls. Anyway, our modern house is one story, and has an intentionally-uninsulated concrete slab on grade foundation, so we get a similar effect. (Passive solar heat keeps it toasty in the winter.) We usually have our windows open, but we also over-insulated the walls (for noise and efficiency), and have a tight building envelope, so the heating/cooling bill is tiny. (Edit: I bet they vented the walls into the attic and under the floor. That'd create a strong updraft in the summer (out the attic vents), but (if the attic is well insulated against the rest of the house) not in the winter. |