I have a nice predator proof coop that offers shelter but is not completely draft proof, plywood on the sides and a roof. If I hang a heat lamp in there are my 3.5 week babies going to be warm enough in 55 degree night time temps? There are 17 chicks total. Right now they are in the garage, just getting a bit much to keep the brooder clean, and I think they could use more space. Thanks.