Finally got around to wintering my hives last weekend; just in time as it will be -12C in a couple nights, with highs of -5C.
I followed the prevailing wisdom of the locals in this area (NW of Ottawa, Ontario, Canada) and pushed 2 double deep hives together and used foam all around, but left a fully open bottom entrance (with wire mouse guard) and small top entrance. The belief is this allows for a small airflow to carry out condensation. I used 1" foam on the bottom and sides, plus 2" on top inside a raised cover that leaves a small gap for feeding sugar patties, then a double wide telescoping cover over all to keep out any leaks.
On my long hive, it is constructed from full 2" pine, so I simply added a piece of insulation on either side of the hive, and a 5" thick box of shavings on top to slow the air movement and prevent condensation. The lid of the hive is already insulated, but has large screened ventilation holes at either end.
Fingers crossed, now we wait and build more equipment for 5 months!