What are some sings that your coop is too humid/cold?

[PheasantsFirst]

Hopefully I posted this in the right forum. This fall I patched some holes on my coop because last winter the chickens didn't seem to be handling the cold well, and there were some very large holes. The coop is 4'x4' and has 12 chickens and a duck in it. The bird spend the day in our greenhouse. For the next week, multiple days are going to have high's in the teens. What are some sings (preferably on the chicken) that the humidity is too high, and I need to add some ventilation?

 

[ChickensAreSweet]

In order to tell if I have enough ventilation, I open the door in the morning when the birds are still in there. I sniff the air and if I smell ammonia, there isn't enough ventilation (I clean all poo out every day since I use sand on the floor). So I make more holes in the coop. I do of course smell the new poo but not ammonia.

 

[PheasantsFirst]

Ok, thanks!, I'll try that in the morning. SO if the ammonia is getting out, there isn't too high of humidity?