You're very welcome! I'm planning on doing something like the last links on my house, maybe this winter. The website Says plan for 3-5 days work...that's for 1100 sq' and someone that knows what there doing...
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But for a coop, probably a lot less. Add in some black water barrels to slowly release extra heat over night, also passive, and it might be enough......
there are so many projects on that site I can get side tracked for hours....
but lots of great ideas regardless. I'm going to put a 45watt 3 panel harbor freight solar system on my coops roof with batteries. We'll see if I can make something like @blooie 's mamabrooder run off of it
to keep the chickies warm.

But for a coop, probably a lot less. Add in some black water barrels to slowly release extra heat over night, also passive, and it might be enough......
there are so many projects on that site I can get side tracked for hours....

