Brooding chicks outside, without electricity or hens...?

Well we did just dive in! We currently have 3 barred rocks, 4 new hampshires, and 1 buff orpington. We lost a chick on night #2 (another buff), but the others seem fine. However, the chicks seem to be kicking up our allergies. They are in our living room right now, as there is literally nowhere else to put them. I have a heating pad draped over a cage wire tunnel. Is it even possible to move them out before three weeks? In another thread I mentioned making a hoop coop...is it possible to go ahead and make it this week and somehow use it as a brooder? I'm considering using a radiant heat barrier and corrugated roofing on it instead of tarp, for whatever that's worth. I think in our climate they'll need the extra measure. It'll be 4'x8' or 8'x8' (roughly), would hay bales inside that be good, or is it just too early for them?

I hope I'm making sense!

It all depends on your temperature. They need to be at 90-95 degrees the first week, 5 degrees or so less each week, with the ability to get to a cooler place if need be. Anything that you do to maintain that temperature will work, but that temperature needs to be constant.

Well it's in the low 70's to mid 80's for highs and 40's to 60's for lows right now; could be sunny one day (or hour) and stormy the next.
Last night they opted to sleep around the feeder instead of in their heated tunnel? They're inside and our thermostat is set at 70. They're a week old now.

They'll really be struggling and getting weak at that low a temperature. They may die, or at best be stunted.

We've had pretty good luck using a kerosene heater to brood chicks.