We purchased the chicken tractor, and soon found it a bit too chilly for northern Michigan. I added the coop the next summer. Now, the tractor serves as a run that attaches to the coop for times when we need to be away for a few days at a time.
There is in-floor heat to aid in coop temperature when it drops below zero during the winter. I added a heated water source later, as the floor cannot do the job by itself.