I have 10 5-week old keets that have been living in a brooder in my insulated tack room in my barn. I moved them into a big, heavy duty plastic shed today that I hope will eventually be the place they return to for roosting at night. It is vented and they have a 16x24 heat plate. It’s going into the high 40’s tonight. Will they be okay with just the heat plate or should I put a space heater in there? It’s the type that turns off if it falls over.