We moved ours (probably about 4 weeks old-ish) to a big mostly open brooder in our non-drafty but not insulated shed. It does have a heat lamp but the set-up isn't cozy by any means. It's been high 30's, low 40's here at night and they have been just fine. We checked them for clumping or piling on each other and they aren't. They do huddle up in a line, like a little chicken power brainstorm meeting. I'm going to try that with the sod. I've been thinking they need more stuff to do in there.