I accidently stumbled upon something this weekend regarding our coop temperature. Temps were plummeting all day long and were expected to stop near freezing during the wee hours of the morning. Unusually cool October in North Alabama.
Anyway, we had recently put up a wireless thermometer in order to monitor the Coop temp & humidity level, and be able to do so from our warm and cozy kitchen. This unit also gives the average high and low readings for the day. Our coop walls & ceiling are insulated with some of those thin blue foam sheets, although not tightly insulated. The coop is draft free. It has a rough-pour cement floor (about 6 thick) which we keep covered with approximately 3" of pine shavings. Ventilation comes from two small windows, on the corners of the S & E walls. Each window can be opened either from top or bottom pane, and we vent the coop accordingly for the season by adjusting the window openings. The coop is 6x8x8.
All that said, late Sunday afternoon I had just finished up with a thorough cleaning of the coop and noticed some excess water spots on the floor in each corner of the coop. I decided that I would manually dry the areas before putting down new litter trying to avoid having any dampness in the coop. I used a hair blower to take care of those wet spots. During which time I had noticed that the coop temp went up a few degrees even with windows and door wide open. Outside temp was now at 49, and dropping. Therefore, I wondered how much I could elevate the temp with the windows & door closed. I hung the hair blower from a hook and left it there for about 30 minutes while I attended to the girls in their yard tractor. Their coop warmed to a toasty 70 while the outside temp now dropped to 47. I put away the hair blower and closed up the coop until it was time to round up the kids for the night (6:30). Once they were back in the coops pen area, I opened the little access door and cracked the windows about two inches at the top. Needless to say, the coop slowly cooled, and by the time they were inside for the night it was hovering at 45 inside and 39 outside. Within an hour of the kids being inside on their roost, the temp began rising slowly. The wireless monitor sits about 2 feet above their roost on the S wall. By 9:00 pm, they had the temp up to 48. It hovered there for quite awhile (I dont sleep well) before it slowly declined back down to 45 by the time we officially get up for work at 3:15. By then it was down to 34 degrees outside yet the coop remained at 45! Oh yeah, the humidity level in the coop stayed hovered near 45% throughout the night hours.
Now for all that rambling, I guess that I am confident that our little coop will do well for our girls. This is our first winter together and yes, I worry. I guess I will only resort to using and heat, like maybe a 60-watt ceramic bulb if we are expecting a severe cold snap. We usually get one or two in December or early January. Cold snaps in our area can last a few days or for a few weeks at a time. Even still, I will be keeping a close eye on the thermometer day in and day out.