My last hatchery order came in Feb. I brooded them outside in a rabbit hutch from the start and they were perfectly fine under their 100w bulb. They feathered out VERY quickly in the cool temps. Since then, I don't brood in the house anymore. Anyway, keep a thermometer under the heat lamp, as long as they have that small spot to warm themselves, don't worry about what the temperature is in the rest of the brooder 
