I have asked this before and not really gotten much of an answer. We have a remote thermometer in our 4'x8' coop. East side eaves are fully vented 4" high by 8' length of wall. One West side vent is open most of the way, 4" high by about 2 feet. We have some gaps around the door, I've closed the gaps in the window and next box. Humidity appears good, there's no condensation on walls or window. This morning we had 28 degrees and the coop was 31 inside. The thermometer base sits nearish the door so may be a bit affect by the gaps. If it's 3 degrees different at 28 degrees, will it only be 3 degrees different at -25? Cause that's coming. Should I be concerned? How cold IS too cold in the coop? ETA: We have 2 full size and 2 bantam hens.