Finiski is right, few understand insulation and venting. Some folks have parts of it right, some don't, some have things confused.
First, when I say venting, I an not meaning full airflow through the hive. Venting is a passive act of allowing a small amount of air with moisture to passively move out of the heated area and still supply a volume of fresh oxygen.
It is much easier to keep a small space at temperature than a large one, but the factors of heat loss will remain the same regardless of size. The key with the smaller size is that there is less wasted space that needs heat. Dead air space is what insulation creates, regardless of the type of insulation. Now you go a wrap a hive in plastic and you just killed the ability of the moisture to permeate (vent) out of the hive.
As soon as that occurs the moisture will condense at any point where the temperature reaches the dew point. Protruding nails will get condensation first. By allowing normal air flow outside the hive (Insulated or not) and keeping the dead air space inside the hive the moisture should not condense at all even if not insulated. But there is still passive permeation of moisture away from the highest to the lower direction...just like heat moves to cold.
Insulation only slows down the movement of heat to cold....not the other way around. Insulation creates dead air space which is where the resistance to the flow of heat is the most. The moisture comes from the bee's normal exhalation and from the ambient humidity. For example fiberglass under a microscope is a bunch of strands crisscrossing all over and those create air spaces. The foams create dead air spaces as the chemicals catalyze, the smaller the better. Cellulose actually has air spaces in the fibers themselves, but it is not suitable for this as it has pesticide in it.
Then, most of this is really mute if you are in a warm climate. My winter climate is cool, just above freezing, horribly wet 40+ inches a year of rain. I will vent. You do as you please. Once the moisture condenses you loose resistance to the flow of heat as water is a much better conductor of heat. Those bees will be fine in an insulated hive with an inch or so of foam on the exterior. The air will stratify and if they cluster it will make it even easier for them to keep their ideal temperature.
I also recently learned from a dude up in a wetter and cooler environment, but still local, and he believes in an empty super at the bottom of the hive below the brood frames. He feels the bees do better in the winter with that dead air space below, which stratifies the cold and warm in the hive...think of it as a basement. He came up with this from getting hives out of trees. Remember, originally before man intervened, in cold climates bees used trees....because they are warm. Wood is an awesome natural insulator.
So, the field of insulation is much more complex than most folks know. Venting is an integral part of making insulation work properly and by doing that, you don't get condensation, even at 100% humidity.
