I believe the bees need to have a balance between a thermally good enclosure and adequate ventilation. Excessive ventilation will nullify thermal retention properties. The need for ventilation varies throughout the season. In eastern Ontario, with temperature ranges from -30c to +30c, ventilation and insulation is required mid winter to avoid condensation freezing and then ultimately dripping cold water into the cluster. 

The recommended practice in Ontario is to wrap/insulate the hives to reduce effect of wind/cold, insulate top to reduce condensation on inner cover, provide small top entrance ventilation. 

Several unintended results can occur. We are currently having a November record heat wave. My hives are wrapped for the long winter in black material to maximize solar gain - for the early spring build up. Instead of clustering at 5c and using minimum winter stores and extending their life span, they are flying at 15-20c and gathering pollen from the odd dandelion. While the weather is fantastic for November it will be a net loss for the bees.

In later winter on sunny days internal hive temps can build so that the bees break cluster and venture outside. The outside temp can be well below freezing and many never return. Many of these bees are near the end of their lifespan but I would rather not see them die so close to home.

When spring brooding starts and risk of freezing condensation is minimal I will close off the top ventilation and hope for sunny days to maximize solar gain. A hive with excessive/extra thermal resistance would not be able to absorb the solar gain. On the other hand it would not lose as much on the cloudy days or overnight. 

A balance is required. 

Regards Peter

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