Condensation happens as a results of a difference in temperature between the outside and the inside of the surface. Viewing windows are much more prone to condensation as they are no absorbant and thin.
like msscha says Ed Clark's book is quite a valuable read
http://www.biobees.com/library/gener...g_EdClarke.pdf.
Depending if you subscribe to the view (which I do) the hive functions as a condenser and heat reclaim unit. By the water condensing onto the sides of the hive heat is lost from the water and released back into the hive to help warm the brood. This works even better in a kenyan style top bar hive as the walls are sloped so:
a) There is greater surface area for condensing (compared to a straight sided of the same depth)
b) Condensing is slowed by the slope into a narrower space providing a greater time for condensing to occur.
c) the sloping sides means the heat lost from the heat rise into the comb rather than back up the sides of the hive. This puts the heat where it is needed and keeps are more consistent air current as it isn't raising into the cooling air.
With all this in mind ventilation is therefore inhibiting that effect.
The ecofloor idea put forward by Phil Chandler if perfect for this purpose.
http://www.youtube.com/watch?v=SWB-pdlqeFQ
For my new hives and retro fitting to old hives the Ecofloor is definitely the way to go for me.
I like the ideas behind the flora and fauna balance in a hive BUT even if all that is rubbish (I withhold judgement on this

) the advantages of this floor for increased temperature and moisture control within the hive are invaluable. It provides an outlet for excessive water when required, but will humidify the air when excessively dry. It provides insulation to the hive from extremes of external heat and cold. It would also works as a reservoir for heat, hive scent, and moisture releasing it back into the hive after you have let it out during a hive inspection. It is essentially a "buffer" resisting any change within the hive environment, thus once the bees have set that environment it will help it be maintained meaning the bees don't have to work so hard to regain it. Not sure how this will work for SHB etc but for me in the UK right now there isn't a better choice for any hive, not just kTBHs.