My boyfriend and I built a coop into what was a green house frame so it has the corrugated fiberglass roofing, not clear but lets in light. The coop is approximately 4' by 6' with a 6' by 12' outdoor run for my 5 birds. The girls generally free range all day, and head back into their house around dusk, unless its raining, then they hang out in the covered run. I currently have a heat lamp hanging in the coop with the girls and the temperature here runs between 40 at night and 55 during the day. Is it necesssary to keep a heat lamp year round, or can I unplug it during the warmer months and use it during the winter?