Tommy, I don't live in the north, but the September issue of American Bee Journal has an article by Randy Oliver. The topic is over wintering. This is his conclusion regarding insulation in Northern climates. "...For outdoor wintering (roughly in order of importance), place the hive on a sunny slope, insulate the top of the hive heavily, tip for drainage, reduce the entrance, block the wind with tarpaper or a thin, black insulative wrap, and if the winter will be long and cold, provide a small upper entrance (with a wind block) on the sunny side of the hive."
"...top entrances may be of more value for bee egress than for ventilation, and should always be placed on the same side of the hive as the lower entrance in order to prevent cross drafting due to wind pressure. A smaller entrance may be better than a large one, in order to reduce convective heat loss."
I hope this helps.