I was in an old barn once. In that ole barn I clearly saw a wooden verticle shaft that went right up through the roof into those little houses that you often see on the top of barns.... Like a chimney. The chimney came right down near the barn floor with a few holes in the second floor. I stuck my head in one of those holes. The updraft induced was incredible! there would be no way that a fan could have moved as much as this ancient tech. Amazing! My hair was blowing straight back! The barn was cool and odorless in-spite of the livestock. 0 Electricity and just taking advantage of the fact that hot air rises as cold falls.