It's really hard to say what you need to do, you've just got to observe and see what's working.
Humidity and direct drafts are not good.... the freezing temps they can take, but their water source needs to be kept liquid.
If you've got condensation on the inside of the coop, which is caused by too much humidity and probably first gathers on the inside of the window glass, then you don't have enough ventilation.
Previous poster suggested just going in and feeling the air movement conditions and adjust your ventilation by that...it's a good suggestion.