Just a thought as I sift through this discussion - the articles by Derek Mitchell such as in International Journal of Biometeorology (DOI 10.1007/s00484-015-1057-z) make a pretty convincing argument that one way to accommodate the bees' needs is to seal and heavily insulate (~R6 or better) a bottom entrance hive.  This mimics the tree.  Experience also shows that modest top ventilation of an uninsulated hive can prevent the obvious condensation problems of having live animals respiring inside a very cold box.  Their survival clustering reflex allows them to survive this through the winter as long as they don't get too wet.  But they may need more food than their tree nest friends, or not.  Some think warm "active" bees eat more than cold clustered bees during winter.  Good research topic.

So you have a 2x2 matrix of insulated/uninsulated vs ventilated/unventilated.  The insulated/unventilated works (this is the tree style nest) and the uninsulated/ventilated works, this is the commercial hive nest.  The insulated/ventilated option may be helpful in very cold and snowy locations due to extreme cold and blocking of a lower single entrance by snow, but in more modest climes, may be a waste of time and insulation.  The uninsulated/unventilated  model has been shown to frequently kill bees in winter weather.  

I am now interested if the insulated/unventilated hive will work in the summer.   I will be trying that this year here in central North Carolina with some of my insulated-unventilated overwintered hives (which all see to be dry inside at the moment).  

A provocative thought from Mitchel's article above is "Many honeybee behaviours previously thought to be intrinsic may only be a coping mechanism for human intervention; for example, at an MCR above 2 KgW-1K, clustering in a tree enclosure may be an optional, rare, heat conservation behaviour for established colonies, rather than the compulsory, frequent, life-saving behaviour that is in the hives in common use."   (MCR above 2... means a well insulated tree cavity)

Brad in Chapel Hill, NC

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