Good job on moving forward with coop construction. Are you asking for input? It seems so, so I will offer my thoughts. I see you are concerned about the comfort of your ladies, but I would forego the heater. Even the folks in Alaska advocate not using a heater. I think it could be especially troublesome in a coop the size you are building. My girls seem happiest on the coldest days and I wouldn't deprive them of that. Growing up in northern MI where it gets seriously cold, we never heated our coop. Start watching the coop threads, it's that time of year where you'll begin to see all sorts of reports of coops burning down because they were heated. It happens every year in the fall. I'm not saying that will happen in your case, but you should be aware of the very real possibility.
The fan sounds like a good idea and I may even add one next summer.
The coops that have inspired you and Mrs. Demosthine are very cute, but probably not the best for our climate, at least not without some tweaking. I would seriously think about ways to make entire walls ventilated. If there is not enough air exchange inside, they may not want to go inside to use it. Situating the coop in the shade will help, but there will still be heat and moisture build-up from their bodies and respiration. Perhaps a fan would help with that, but I think it's best that air exchange can happen very efficiently and passively as well. These thoughts are just my 2 cents and probably worth that too.
You made some excellent points on the fire issue, which is why I was looking at the induction panel type heaters. They are supposedly to be completely safe for situations like this, since they are especially safe for use in the brooders for the chicks. I hadn't heard that they do really, really well in winter, though, until you mentioned it. I'll leave out the heater idea for now.
The coop will be sitting on my covered patio, with no direct sun at all and two ceiling fans on the porch. In regards to the ventilation, it should have plenty of that when I'm done. I was going to put the fan in the bell tower as an intake, so it would pull air from outside down in to the coop and push the warmer air out the bottom windows. I think Harbor Freight had some solar powered ones a few months ago. There will be two windows on the front, along with the 12"x18" open door. There will be two along the side above the nesting boxes, too. The coop will also be sitting directly in front of a large window and I would like to design the back wall so that I can open the window and allow the AC from my house to flow in to the coop during the extreme parts of summer. That would mostly be during the night, though, since they'll be out free-ranging all day.
The way my wife is taking to the girls, I'm thinking I also need to design it so that she can open the window blinds and be able to see in to the coop as well. I think she'll get a kick out of being able to watch them from inside the house. It is in a great position for her to watch them from our dinner table, too. I haven't quite figured out that back wall yet, but it's on my list today. The girls are quickly outgrowing their little Rubbermaid container, I need to get them in the coop by the end of Wednesday. It'll just be chicken wire or hardware cloth wrapping it for now, until I can do the detail work for the wall coverings.
Just for reference, here are two items I've leaned towards after a few quick searches. The
Dog Palace Solar Powered Fan is about the right size for fitting in the bell tower perfectly. I might have to take the fan out of the rectangular mount so it'll be a smaller square mount, but that may be too small. I want to get actual dimensions of the fan and output before I commit. I have a few months before summer, though.
For the heater, I was thinking something like the
Hound Heater would work well. It mounts securely, but safely inside and has a very wide range of thermal switch temperatures. I can mount the solar panel on the patio roof directly above the coop and run the cable down about two feet in to the peak of the coop's roof.
