@TechConnectify another excellent video as always. Love how passionate you are about mundane things and show us how interesting they really are.

Regarding your comment on vestibules, I found it very surprising that you mentioned never seeing ones where the doors don’t open at the same time. Especially as I gather that you get pretty cold winters there! Here (NL, with very mild winters these days) I wouldn’t say they are a common occurrence, but they do exist and they are usually set up to behave like that in winter and not in warmer months exactly like you suggested. I don’t often see vestibules in the first place though. High traffic areas like shops just have massive heaters above the doors which blast down hot air, or there are revolving doors. Those usually have three or two compartments though, this seems almost unworthy of mention but since you specifically mentioned four you might not see those often? Idk the world is a varied place sometimes!