"I live in a place colder than you and raise the chicks outdoors. I use an old fridge with a chook size hole in it to give them shelter from ice, snow, and the freezing effects of exposure from the sky. Ice forms on pans of water outside, but the tiny chicks are all fine in a fridge, which after all, is designed for separating warm from cold."
I have a feeling I am going to regret this but here goes ...
You have hinted in other threads that you are in Australia. If that is the case, using -25F as a possibility in say Northern Wisconsin where blucoondawg is located, that converts to -31C for Aussies .. the lowest ever recorded temperature in Australia was back in 1994 and it was -23C [-9F].
I believe your suggestion may carry more weight and credibility if you were to expand on where you live that is colder? What temperature extremes have you used the fridge in? Have you tried it in various climates or just the one you are in now?