Yeah, sorry - somehow I missed that the first time I read it. Let's just say I should never respond to a post before my first cup of tea in the morning...
After rereading the OP's first post, I think you're right...
OP, I'm changing my response to, "Yes. Keep the door open. The only time I shut mine is when it's down to double-digits below zero."
A foot tall, a foot wide, and how long? Depending on where you live an what your winters are like, your chickens very well could choose to spend most of their time in the coop. Personally, if you have more than one chicken, I'd try to build or buy something with more room for them to roam around...