>If you've got condensation ice melting and running
down to the floor on warm days then you have ice formation encapsulating
dead bees and hive debris on the floor on subsequent cold days ... which
then thaws to create an unhealthy moldy mess during the days of late
winter.

This is a valid point. But this is exactly one of the reasons why I said that 
well insulated hives without top entrances work here best with net bottom. The 
modern ESP bottoms are designed to direct the water out. All surfaces on inside 
are tilted directing water to bottom net. The water runs through the net edges, 
most dead bees on bottom stay totally without contact to melting water. Dead 
bees stay quite dry, and easy to brush off on spring. No mess that is common on 
wooden bottoms.

If we think the heat balance, it is maybe good that the water codensates and 
freezes inside the hive in cold days. Condensation/freezing releases energy, so 
the inside should be a bit warmer when the weather is coldest and most 
difficult for bees. Ok melting the ice takes energy back but that is much 
easier for the bees as it happens on days that are on + and the incoming air, 
not the heat from bees melts the ice.

In temperatures that stay for long period on low side of -15 ? 20 C you will 
end up with ice inside the hive if you have any kind of roof on top of the 
bees. If the bees are down in the hive you get ice on top of them, even if you 
don?t have a roof. Have seen that in hives that lost roofs in storm. So I can 
not see how any  amount of ventilation would avoid ice inside the hives here.

When first ESP hives with net bottoms were introduced in 80?s old time 
beekeepers declared them death traps for bees. All bees in ESP hives would die 
in winter because no ventilation upwards and net bottom letting cold air in.  
Now, after 25 years of experience, the general view is that wintering is better 
in these hives ???..

Ari Seppälä
Finland

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