Re: Wintering question for northern beekeepers
I agree that insulating helps moderate the rate of temp change inside the hive when ambient air temp drops and rises.
Find the interior temp of the hive just above the inner cover is 20 - 30F warmer than outside ambient. The 30F differential occurs at colder ambients and I attribute it to the extra heat that the cluster generates to keep interior cluster temp at ?90F. The interior hive temp drops somewhat and the clustered bees then generate more heat.
I do add black building paper over styrofoam. I have tried styrofoam on three sides with none on the front and black paper. On a sunny yet cold day, it seemed to fool the bees into cleansing flights and many did not make there way back to the hive.
With styroam on all sides under the black paper I suspect the benefit of black paper is limited. A little thermal gain and somewhat of a wind barrier. I don't fasten the top of the black paper with tape and must be getting enough ventilation so exterior of hive does not get damp.
I use two 1/2 by 3/8 side bottom entrances and a 1 1/2 by 3/8 top entrance. I also have a 3/4 round hole in a feed rim just above frames. Get good ventilation of moisture out through round hole and 1 1/2 opening. They build up with frost in colder temps from the moisture from the bees.
Also have 2 inches of styrofoam in telescopic cover.
I also experimented with quilt boxes above my inner covers last winter. All in all, seemed to keep hive interior very dry. Moisture build up on side walls is not all bad as it is a source of winter water.
Have had the cluster starve with feed in frames nearby. Need to ensure you have 10 full frames in top vrood going into winter. I add sugar candy blocks on top of the frames on a warmer day in late December as exta food and a source of food so cluster does not get stranded. Lost one out of four hives that I attribute to deformed wing virus.
If you always do what you always did, you'll always get what you always got!