In fact, and back on the topic of this thread, some might argue quite strongly that having some doors opening into the saloon from time to time would be an advantage. Just for example, in vehicle 812004 of set 800004 yesterday, mid-morning, when the outside temperature was around 13°C, the inside temperature was 25°C and the humidity 74% (measured after the train had been in passenger service for well over an hour, so not “just off the depot”). Both of those values are above comfortable values, the humidity substantially so. I wonder who/what has control of the air conditioning on these trains, and whether this very unpleasant environment was due to incorrect settings (in which case who allowed these settings to be set?) or failed (1 year old) equipment (on a very easy day to deal with, in terms of weather). There were certainly systems switched on and moving the air around, as evinced by the constant loud whistling sound from the vestibule/saloon doors, caused I guess by a pressure differential between the saloon and the vestibule (or maybe between the carriage and the adjacent carriage or some other pair of separated but not sealed spaces …) and the ear-popping on release of the door seals.
I considered a fellow traveller's assessment of “sauna level” to be hyperbole, but agreed with his sentiment, and considered his electing to stand in the vestibule, so as to be in a more tolerable environment, completely reasonable.
