I remember seeing a very different approach with a very similar goal in Vietnam. In Hanoi, many houses have a small greenhouse-like glass structure on the roof

I remember seeing a very different approach with a very similar goal in Vietnam. In Hanoi, many houses have a small greenhouse-like glass structure on the roof. The greenhouse has a chimney. When the sun is shining, it gets hot in the greenhouse and the hot air escapes through the chimney. A hatch through the roof into the greenhouse draws new air from below, essentially creating a passive, sun-powere air-flow through the whole house, bottom-to-top. Usually some windows on ground level are left open to let air in.