I've got 3 RIR. They have a A frame tractor coop. My question is related to nighttime temps. Oh, and I live in NC and our evening temps have started dropping into the 40's this week. I understand that RIR are okay in cold weather. We have two drop down "hatches"/windows (triangular in shape) on either side of the coop w/ hardware cloth that we were keeping open during the summer for ventilation and to keep them cool(er). At what temp should I shut one or both of these? I have started shutting one side and have been leaving one open. I don't want them to get too cold. We're not doing a light in the coop yet for them so there is not that additional warmth. Any ideas, guys? I'm clueless. I just don't want to make my birds uncomfortable. Also, any other hints now that fall is here. Thanks.