The temperatures and ventilation have not been an issue where I live. It's so dry here. In the summer we keep the door closed between the coop and greenhouse. The door is insulated and the coop has all the vents at the top,so it stays quite cool. After building my planter in the greenhouse this summer I found it to be a great thermal mass. It has a lot of soil and there's a reserve of water in the bottom of it. It kept the temperatures from swinging too much. Before, when I had small containers in there, I found it difficult to keep from getting too hot during the day and I had to put a heater in there at night. This year I didn't use a heater and my tomatoes never froze.
I have never used a heater in my coop even when the temps were well below freezing. I have a small fish tank heater set on a timer in a 5 gallon bucket of water with horizontal nipples. It keeps their water from freezing, but I think it also helps the temp in the coop. That and heat from the birds themselves keeps the coop comfortable. I have 11 chickens now....chicken math. Lol!
Edited by highrockieschic - 12/14/15 at 1:02pm