I use wooden hives, 3/4 inch thick pine or cypress, estimated R=1.5. The problem here is that moisture accumulates inside the hive and eventually triggers dysentery. A small upper entrance that vents the moisture eliminates the problem. A typical colony winters on 3 to 4 kg of honey, then ramps up brood production in February with highest stores consumption in late March. Total winter consumption is about 20 kg before fruit bloom in spring. The critical time period is from Feb 1st to April 1st when moisture can condense inside the hive and temperatures often dip to -10 at night.
The most critical factor in wintering here is blocking the wind. I've had colonies fail because there was nothing to stop wind from blowing around the hives. I maintain 4 colonies on a stand at .5 meters above the ground. The colonies are pushed together in fall.
Anyone who insulates a hive with leaves deserves the results. Leaves absorb moisture until they are saturated at which point they are less than worthless as insulation.
I give a lot of credence to Finman on wintering. His climate is challenging.
You have moisture on the walls and need to ventilate because the walls are cold and the bees need to metabolise a lot of sugar to stay alive. If the hives are insulated and or sheltered (e.g open front shed) then the walls will be warmed and your bees will produce less water. The dysentry /nosema is primarily a function of the cold rather than the moisture.
The mode of beekeeping you have originates from the 1930s&1940s when insulation was expensive, heavy, time consuming, low performance and in short supply.
Thus the solution for overwintering, promoted by C.L. Farrar was no insulation but big colonies, lots of stores and ventilation.
Today insulation is cheap, abundant, light and high performance. However, this means no top ventilation or top entrance to avoid desisication of the bees. In snow bound areas it also means lifting hives or sheltering them from the snow.
Honeybees prefer elevated nests for good reason!
This means you chose a method of beekeeping that will mean drastic reduction in your requirement for food but it does mean more changes than just insulating.
Why dont you dessicate your bees now? The dessication comes from the stack or chimney effect. In a classic wooden hive in cold climates the air is chilled by contact with the inner/crown board and so the stack effect is reduced.
.....just making a point and maybe being a little mischievous...and yes very bored now!
