I have a small shed that I use for my goats and poultry. I have a hole cut into the wall for a "doggie door". Come winter, I need a good windbreak for it. It faces south, which helps also, but there are a few days where the wind still does brush around the snow pretty good, and a door aso keeps the heat in.
So, what do you all use for coverings? It has to be pretty simple. My goats are good at understanding how to get in, but the chickens and ducks are another matter.
First, what I do is I nail the carpet (or whatever) over the door and cut into strips. I leave the middle strip nailed up also for a bit, about 2". This shows the chickens that they can still get in there, and it does work, as eventully I can pull down the other strip and the chickens still use the door.
However, finding a suitable material to use is another matter. So far, here's what I've used:
--regular carpeting. Works well, is soft and pliable even in low temps, so stays straight down and keeps the warmth in. I nailed it down so the rubber is facing outside, to keep ice and snow from building up on it.
The downside is that the goats (who are all hornless except for those in a separate buck pen) somehow get the fabric torn into shreds, and I'm left with long threads of rug everywhere. Probably not the safest thing, as it could wrap around legs, etc. If you decide to use carpeting, avoid any that have the kind where the material comes out of the rubber and then "loops back" into the rubber (not sure what that is called).
--harder, tougher black rubber mats. Works great til the cold hits, then it becomes stiff and doesn't make much of a decent seal around the door, so the cold gets in. Depending on the material, the flaps will sometimes curl up or just not lie straight down anymore, becoming useless.
I have been thinking of trying burlap, perhaps several layers on top of each other, but the only burlap I can seem to find is very thin and woven loosely. I suspect it will also pull apart once a thread gets hooked on something. Ditto for the plastic burlap feed bags (of which I have a lot of).
I was thinking of maybe getting some polar fleece (as it doesn't shred or pull easily) remnants somewhere, maybe getting a blanket from GoodWill. Any other recommendations for material?
It's amazing how well a flap works to keep heat in. Several of my chickens will lay eggs all winter long if the heat stays in, all without the use of a heater. Then again, we have windows in the shed to keep it bright and the walls are light-coloured also.

I go into the goat pen to "warm up" while doing barn chores.