I'm pretty sure the "cool tube" idea described above and in other literature is mostly a dryland strategy. When I made one in central GA it quickly became ineffective, probably because condensation filled the lowest point in the tube with water and airlocking it. If it were made with a clear uphill flow all the way to the house there would still be the danger of excess humidity and mold. A tour of
permaculture sites in the SE (Earthaven in NC for example) will point up the challenges of mold in "alternative" building systems such as
cob.
A look at the historic district of any Southern town will point up the default design, which is repeated in many hot humid climates worldwide.....high ceilings, wraparound porches, ventilated gables or cupolas, raised floors. The Cracker house made a lot of sense.
The design challenge, at least in a climate like Georgia, is that that building style relied on abundant
energy (
firewood) to heat the space, or portions thereof, during the cold season. During most of the time when this vernacular architecture was being developed, firewood was abundant. And on any rural landholding in the South or East, it may well still be abundant.
So one way toward progress is to begin to add insulation to the classic design. The goal is to be able to close the space well in the cold, and so save fuel, and yet be able to open it competely in the heat......