How to deal with drafts

[Desirai]

So this is my first year with chickens. I've had them since March. Winter is comin!

I live in eastern Alabama so our winters are mild but it can get below 15 degrees F sometimes.

How can I protect my chickens from drafts? all summer long I have kept their chicken door open 24/7 so they can come and go as they want inside the run.

should I start locking it during the winter? I've noticed that rain is able to soak a couple square feet of the inside of the coop, but chickens can still get into the back of the coop away from the rain.

Are chickens smart enough to do this? So far I have a handful that like to sleep outside in the run on the perches... will they stop doing this when it starts getting colder?

 

[ChickenCanoe]

The rain is a problem in winter because of humidity so I would try to shield openings to keep rain out.
Other than that I wouldn't worry about it.
What breeds do you have? Chickens die from bad air, not cold.
I would NOT coop them up.

ETA
I have BIG windows (covered with hardware cloth) on East and West side of coops open all winter with no problems.