I visited an arts & crafts festival yesterday, which is themed on life in 1855. Part of the exhibits were a group of fur trappers, one of whom had a bonafide teepee set up with full furnishings and paraphernalia of the time period and culture. (He explains this as (in character) that he's married to a Native American and so, the teepee is their home instead of a trapper's traditional tent or dugout.) He had a fire pit in the center, cooking his dinner. So of course the conversation turned to how it never gets smoky inside, and how it stays warm in winter with that big hole.
Well, my chicken friends, I had an eye-opening experience studying the construction of this teepee, and it explains VERY well how proper ventilation pulls moist air (or in his case, smoky air) out, yet keeps the interior warm and draft-free.
I am very sorry I did not take a photo for you. But I'll try to explain.
It's not just a simple smoke-hole at the top, although there was a sizeable one in this teepee. This is the secret: There was a double layer to the walls. The outer layer (what you normally think of with a teepee) went almost - but not quite - all the way to the ground and up to the top of the apex, or smoke hole, oh maybe 18-20-feet high. There was an inner layer of fabric/leather/canvas that went all the way around the inside of the teepee, but only about 5' high, affixed to the teepee poles. This layer bunched a little on the ground on the inside, and was placed on the inside of the teepee poles, so that there was a 3-4-inch air gap between inner and outer layers all the way around. (Standing up, you could put your hand and arm into the gap between these layers.)
This design allows for cold outside air to enter below the bottom edge of the outer layer, and is pulled upwards by rising heat from the inside. This rising heat actually creates a sort-of vaccuum that pulls air inside and up. The inner layer protects from drafts and keeps it warm. He can control the amount of air movement by lowering or raising the flaps on the outside layer. In summertime, the inner layer and/or outer layer flaps can be removed or raised as well for better cooling effect.
Amazing, eh?
Well, my chicken friends, I had an eye-opening experience studying the construction of this teepee, and it explains VERY well how proper ventilation pulls moist air (or in his case, smoky air) out, yet keeps the interior warm and draft-free.
I am very sorry I did not take a photo for you. But I'll try to explain.
It's not just a simple smoke-hole at the top, although there was a sizeable one in this teepee. This is the secret: There was a double layer to the walls. The outer layer (what you normally think of with a teepee) went almost - but not quite - all the way to the ground and up to the top of the apex, or smoke hole, oh maybe 18-20-feet high. There was an inner layer of fabric/leather/canvas that went all the way around the inside of the teepee, but only about 5' high, affixed to the teepee poles. This layer bunched a little on the ground on the inside, and was placed on the inside of the teepee poles, so that there was a 3-4-inch air gap between inner and outer layers all the way around. (Standing up, you could put your hand and arm into the gap between these layers.)
This design allows for cold outside air to enter below the bottom edge of the outer layer, and is pulled upwards by rising heat from the inside. This rising heat actually creates a sort-of vaccuum that pulls air inside and up. The inner layer protects from drafts and keeps it warm. He can control the amount of air movement by lowering or raising the flaps on the outside layer. In summertime, the inner layer and/or outer layer flaps can be removed or raised as well for better cooling effect.
Amazing, eh?
So you can't rely on the chickens to be a heat source and drive a current up. There shouldn't be any heat source in the coop, that's why this technique isn't practical for chicken coops.
