First time chicken owner here. I have a small backyard flock of six white leghorns, sixteen weeks old. Five girls and a rooster. They're doing just fine... as happy and healthy as can be. But as we head into fall and its cooler temps, I'm wondering how exactly to manage the balance between...
The ventilation should be near the top of the coop, above the chickens heads while they are roosting. Proper ventilation will help ensure that the bedding doesnt get too wet and cold. Use deep litter in the coop.
Learn how to construct an aesthetic yet working chicken coop with an automated egg farm in Minecraft.

By finding the right balance between warmth and ventilation, you can ensure that your chicken coop is a cozy and healthy space for your chickens to live in during the winter months. Adding The Correct Type of Roost.
Chicken Coop Warmth.You also need ventilation so that humidity levels are not to high (our roof is ventilated.) We added weather stripping to the doors and cracks to keep out the wind.

Ventilation is super important in a coop (I learned), so we added these windows.This might be my favorite thing about the whole build. I think its the cutest addition! And I love that the kids can (with a stool) open the top door to watch the chickens without the chickens trying to fly the coop.
Chickens Don't Need Heat in their Coop. I agree in principle that heating your coop isn't a good idea because of the fire hazard and because your chickens will be a lot more hardy and healthy if they are allowed to naturally and gradually get used to the drop in temperature as winter progresses.
Chicken coop nesting box; this is the place where each chicken will eventually lay an egg, and you need at least one for two hens; the box ought to measure 12x12x12 inches and be elevated 10-20 inches above ground.