I will be receiving 27 day old chicks in early feb. It will be quite cold here. I am planning to keep them in a shed near the house. It has electric for the light and screened windows for ventilation. I plan to make a brooder inside this shed as i don't want to give the entire shed over to the chicks. question, how large of an enclosure will I need to make their brooder? And how long until they can go outside?