coop open on two sides- ok in Atlanta winter?

I have an unused lower level to my garage that basically looks like a barn with two big open doors on the front.  I want to convert it to a chicken coop but don't have the resources to have barn doors built right now.

My plan is to divide the barn down the middle and make half of it the coop, with a run that extends out into the garden.  This would leave the coop covered and surrounded by real walls on two sides. A third side made of chicken wire would be inside the barn but not really closed off from the outside air that flows in through the open door.  The fourth side  (one of the barn doors) would be covered with chicken wire but otherwise be open to the outside. 

My question is this:  will my chickies be ok in the winter with this setup?  

I live in Atlanta, climate zone 8.  I think we rarely get below 20 degrees F in the winter.  I think I could put the roosts and nest boxes in the back corner, the farthest away from any cold air.

Thanks,

Esther