I do know that ventilation in winter is just as important as in the
summer, but for different reasons. Condensation within a hive is
detrimental when the water "rains" down on the bees. I don't know how
many people have noticed but water can and does evaporate directly from
ice to gas. In the coldest of winters when the sheets of ice are coating
the parking lots and untouched stretches of pavement slowly disappate
even when the temps are -35F. Without ventilation in the hive, the
condensation AND ice that may build up on the inside has no way to be
vented out, but is captured at the roof since it is warmer than the air
below it because of heating by the bees. I know water condenses from hot
to cold, but heat rises and retained humidity cannot escape without
proper ventilation.

There are some beekeepers in the far north I know who use bottomless
hives or screened bottom boards and report they have had better
overwintering success because of the ventilation afforded. The bees
retain the heat because heat rises and remains traped, but the free
flowing very dry air below can draw the humidity out of the air the same
way that ice magically disappates in sub-zero weather without seeming to
melt first.

--
Scot McPherson
The McPherson Family Honey Farms
Davenport, Iowa USA

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