>They have no control over ventilation.
Ahhh, but they do, if there isn't too much. Huber's research showed that ventilation was less with more openings than the standard one (this was in a skep, not a Langstroth and there was no top entrance), so I think having the entrances such that the bees can CONTROL the ventilation is more important than having a lot of opening. Bees fan to control ventilation. They control the actual path of the air as well as the volume with fanning bees.
Ahhh, but how can they control ventilation when an external colony can have no walls nor floors nor ceilings nor entrances? The partial quote that you've shown is out of context with the rest of that post. Good response for a closed cavity but I don't think it works for an external colony. :)
I'm not arguing the point whether bees can and will control ventilation within an enclosed cavity...I did a cutout last year on a colony where the cavity was a sandwich of two 4x8 pieces of plywood. The colony was at the top corner on one end, at the other end a piece of channel iron made the top frame piece...at the opening in the end of this iron bees were fanning/ventilating the cavity though the colony was 8 feet away. So yes, I believe they can and will control the ventilation to the best of their ability.
What I'm trying to get at is whether there is a more micro aspect of the cooling process...that the evaporative cooling takes place at the surface of the comb and that any cooling of the rest of the cavity is incidental. The only way an external colony could cool down would be doing it this way being as any slight breeze that came along would rid them of any cool air floating outside of the thin boundary layer of air surrounding the cluster/comb.
On a somewhat related topice, something that continually amazes me is that the bees can work honey down to 18-percent (and less) moisture content in an environment that regularly ranges from 30-50 percent humidity. Amazing creatures.
Whatever the case, the bees have been surviving regardless of what we do...God's will they will continue to. :)