Visited my beeyard yesterday and the difference between tbh and lang ventilation was obvious. The bees were hanging out on all the lang and my combo hives. The langs are equivalent to 5 deeps and the combo has the equivalent of 5 deeps above the hive. Yet, these bees were hot and were hanging outside to reduce temps inside the hive.
The tbhs were not bothered by the heat. Bee activity was normal at the entrance with a half dozen bees fanning. I lifted the cover which is blocked up above the top bars. The top bars were cool to the touch.
I had commented on this difference last year but I've lost the thread. The difference between the two types of hives, those using frames and those with natural comb is very obvious. The combo(long) hive with frames had the same problem as the Lang hives with frames. The tbh with their natural comb attachments and very little 'free' space surrounding them are much more efficient at controlling the ventilation and temperature.
The extra 'gaps' in Lang equipment must hinder the bees somehow.