Just normal air movement from inside the hive.
I don't understand that. I have no condensation problems either.
I have warm hives and consumption of winterfood is from Semptember to end of April on average 20 kg sugar.
No starvation problems.
Nosema makes nuisance every winter. That I compensate with 20% extra hives.
I learned moisture lesson when I lost 6 hives 40 years ago. None of these had upper entrance.
Just now we have here -10C to -20C frost and sometimes a bad wind.
I dunno...I'm just telling you what I have going on. Our winters are not nearly as bad as yours so maybe that is the difference maker. :-)