I can’t brood indoors and I live in Ohio where it has been C-O-L-D. Coop is completely uninsulated. One morning the temperature inside (INSIDE!!!) my coop was six degrees.
I thought for sure I would open the door and find frozen chicks. Instead, my tiny, downy, three-day-old chicks were having a blast in their frigid brooder. They were running around, eating, drinking, checking out their digs, and only occasionally darting under Elecrric Mama for a little warmup.
Those same chicks are now 3 weeks+ and doing extremely well. It was in the high 60s today and I had the coop wide open and the chicks hardly spent any time at all under Electric Mama.