Yet another ventilation question: vent placement

[elmo]

Ok, I've decided to build a small, winter coop for my five serama hybrids. I live in North Texas where we rarely get freezing weather, but we do get stretches of winter weather that dips into the upper 30's at night. This coop would be used only during winter.

I'm going to roof my little 4' by 4' coop with clear polycarbonate panels, and put it in a sunny location, so that the sun will heat it up during the day. The chickens will be out in their run during the daytime, so I'm not worried about it getting too hot in there for them during daylight hours. I'm hoping, though, that the retained heat from the sun will help keep them warmer during the nights.

My question is about where to put the ventilation vents for this coop. Traditionally, the vents would go on the tops of the walls, but it seems to me that this would just defeat the purpose of the "greenhouse effect" -- the warm air would just vent out of the coop.

So I'm thinking of putting the vents down below the level of the roost. That way, it would be the colder air that vents. Does anyone see a problem with this? Would that create a draft within the coop, even without any high vents in the coop?

 

[patandchickens]

The point of wintertime ventilation is (in large part) to get rid of humidity, right? And the warmer air is, the more water vapor it holds. Thus, the warmest air is what holds the most moisture, and thus is what you most WANT to get rid of.

Frankly I do not think you are going to get much nighttime-temp benefit from your setup unless it has unusual construction to add quite a lot of thermal mass. A 4x4 cube of air cools off pretty quick, even with insulation. I am not sure that heating it up a whole lot during the day is such a great idea anyhow -- it is hard for me to believe that very large temperature swings are good for chickens, they are hard on other animals certainly.

If you want to do what you describe, I would suggest investing in some serious thermal mass features. Such a small coop might (??) not "need" too serious a foundation, especially if you could live with a little shifting/cracking and could locate it on pretty good solid compact soil or rock ledge; in that case, something like cement-filled cinderblock, with insulation on the *outside*, or strawbale construction (meaning the complicated version with rebar and chickenwire and stucco), or cordwood construction (again the complicated version with mortar and sawdust), might work. Or you could just build the coop significantly larger, and put sealed jugs of saltwater on the floor and along all the walls (secured so they don't fall over!), probably with the thinnest possible metal panelling to separate them from the chickens for hygeine reasons. Set up that way, you could probably pump quite a lot of solar heat in there before it became problematically warm, and it'd last through the night pretty well even with some ventilation open.

Otherwise, honestly I think you would be best off constructing a conventional, conventionally-ventilated coop. If you think you can get away with shutting down the vents at night, do; that would IMO be better than having the top shut but floor-level vents open. But this would require relatively few birds per unit area, and good sanitation.

JMHO, good luck, have fun,

Pat

 

[elmo]

Thanks for your suggestions, Pat.

I think what I'm going to do is put in vents both at the top and at the bottom, but put tightly fitting doors on them, so I can open and close as needed while I'm figuring out what works.

Humidity in winter is a factor, certainly (although any nights that we dip below freezing I'm likely to bring my little chickens indoors, to our birdroom). Air quality is also a significant factor, too, because chickens like all birds have very efficient respiration systems and are much more sensitive to polluted air.

If I had standard chickens, or even some of the cold hardy bantam breeds I wouldn't be so concerned about heat; it's just that I'm not sure how cold hardy my Serama hybrids are going to be, and this is their first winter. So we'll see. I'm sure I'm going to over-engineer this coop.