>If you are looking for a general consensus, you're posting to the wrong
group!  

Words of wisdom indeed and a great observation of the beauty of this list.

There can be no "right" answer to top ventilation because... (get ready)... all beekeeping is local. Way back in the last century I had yards in the maritime western side of WA with a climate as Jennifer described, Talk about sensory deprivation! Weeks when the temp would not get below 40 nor above 50 and uniformly dark and dismal. The bees did great with wide open bottoms and the top propped with a 1/4" shim. 5 framers would do just fine and even some baby mating nucs would get through the winter provided they had ample stores. 

Here, same latitude but very different climate, I have experimented with a number of different wintering configurations to come up with the one most successful for me. Some basics that I think most of us do agree on is that cold is far less the enemy then wet to a well provisioned colony. So the "right" configuration is one that allows sufficient ventilation via the chimney effect to expel excess moisture without undue heat loss. Too much top ventilation no matter how well insulated is like having a well insulated house with the furnace going but the windows open. In this case the furnace is the girls eating honey and shivering. To little ventilation will turn the interior into a steam bath as the natural metabolic moisture builds up and condenses on the cold exterior surfaces. If it's on the top cover and it stats to drip down on the cluster, big problem. If on the side walls and outer frames excess mold will develop. While maybe not changeling the colony survival it will be a mess in the spring and deprive the colony of stores. 

 All my colonys winter as double deeps with 10-12 frames of capped honey. Several years ago I did an experiment with 50 colonys tar-paper wrapped and a 1" foam top sheet under the outer cover but above the inner with a 1/2" grove routed in the foam to allow some air escape. 25 with wrap but no foam and 25 just the naked double deep and top propped by 1/4" All have entrance reduced to 3/8" X  6". Mine are a foot off the ground and snow blockage is not normally an issue for more that a week or so at a time and so I don't worry about it. Wind is not excessive and most days have some sun. For 6 weeks around the turn of the year it can get below 0 F for some days and below freezing for 3-4 months. The results were clear for me here. No noticeable difference between wrapped and unwrapped, sans top insulation, with virtually no mold. Those with the top foam and wrap had much more mold and a soggy pile of dead bees on the bottom in spring indicating to me too little ventilation. Survival was not statistically different amount any group. Around 10% loss as I recall.  

My 2 cents. Tar paper or other thin wraps are wind protection only and not significant thermo insulation. Not a windy location, don't bother. Top and sidewall foam insulation is a delicate balance between having enough ventilation (cold air in) and the benefit of the increased R value. Bees insulate their cluster very well and the temperature a couple inches from the cluster is ambient. They do not heat the entire cavity. A hole in the top box is only useful as an escape if the bottom is blocked by either snow or dead bees but if that is not an issue a propped top is more protected and easier to regulate. I don't know about absorbent material on top, hard to see how it could help over a long winter but I have no experience.  My saying is that the best insulation is frames of honey. Well fed, dry bees will do just fine in most climates without additional insulation. I'm not talking about the Yukon or even the wind swept Canadian prairies but most of the rest of us. In milder climes, moisture is the issue and good ventilation is the key and a lot of insulation will only hinder that. So experiment and find out what works where you are.

Paul Hosticka
Dayton WA

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