Thanks armorfirelady and bear foot farm. I've been thinking over the placement of these. Do you have them on your north sides? I don't know where your prevailing winds come from in the winter but mine come from every direction but east and only occasionally here do they come from the east.
I'd put them right under or near your roosts...that's where most of the humidity will arise each night and having a convection of air flowing up past that area to move the humidity upwards and out will be of the most benefit. When I opened up a similar area under my roosts is when I got to see how that worked and it was great. It's not like a breeze, just a rise of fresh air and that is the kind that will not steal body warmth, just move humidity.