Namble,
That was my concern too, esp being here in PA where it gets into the teens over night in feb/march without any difficulty. However, I was encouraged to go for it som I'm going too. I have a friend who will take them and keep them in her coop (which is really just a shed) if I feel mine is too cold for them, and I plan on keeping them in the house for a cpl of weeks and then taking them out to the shed with a heat lamp when they get too messy in the house. I'm hoping between 1-2 heat lamps in a shed and eachother will be enough to keep them warm until at least 6 weeks when I will probably have to put them out in the unheated barn with the rest of my girls d/t space limitations. I was encoraged to go for it and I am. I figure if it doesn't work out it will be sad, but I'll know what the limits are then. Good luck to you!