If you live in a colder climate, it’s likely that your coop will have mostly solid walls. Check your coop for holes and cracks and make sure you patch them to prevent drafts.
It may also be necessary to insulate the coop to keep in as much heat as possible. One easy way to insulate, and ward off drafts is to stack extra bales of straw in the coop, along the perimeter.
Proper ventilation is still necessary and very important.
When your chickens breathe, they release moisture into the air. Moisture, combined with freezing temperatures in the coop can lead to frostbite. You do NOT want your chickens to get frostbite. They sadly can lose their combs, feet, or their lives as a result of frostbite!
You can also opt to run heaters during certain conditions (such as below-freezing temperatures). Heaters should be mounted safely so that they can’t be perched on or knocked down by chickens. There are special heating plates designed for raising baby chicks or heating a coop.
If you use other heaters, like space heaters, please pay extra attention to safety. Running electricity and heaters in a coop can pose a fire risk, especially if you aren’t careful. If you run electricity, make sure you take the necessary safety precautions. Don’t leave any wires exposed, and adhere to your municipal building codes for running electricity to outdoor structures and settings.