I have my birds in a big pole barn... no insulation, but I do use straw. On the colder days I offer one heat lamp to be used if they want. sometimes they do, most of the time not. I also use heated dog bowls... about 4 of them. When it drops below 0 I put a heat lamp on over the water bowls or I find they freeze up too, and shut that lamp off asap.
My birds do fine on this arrangement.
My birds do fine on this arrangement.