Installer here. They are precisely for what the other commenter said, and for traffic control. Think of the large hoards of cattle, I mean people, that enter and exit large office buildings at the same times everyday. If they were normal swing doors, or automatic sliders, climate-control wouldn't be able to keep up, as the doors would be open the whole time.
this post was submitted on 14 Aug 2023
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Are they objectively more efficient than an airlock system like this, or is their popularity accidental?
I can imagine they are more expensive than a double door system.
If you have a large stream of people constantly entering or leaving the building, both doors will be open all the time. In a rotating door, people can enter and exit simultaneously and constantly but you still have a working air lock that exchanges less air with the outside than a door that is open all the time.
I see. Then it might be a factor of population density. Where I come from, there's way less people moving in and out per building, to put it simply.
That solves it for me.
They also keep the heat in
Yeah, that makes sense. It's the same for where I come from (but keep the cold in, instead), and the airlock system is by far the preferred solution. I think only IKEA insists on revolving doors where I came from.
Yeah only problem with the airlock system is both are sometimes open at once, but with a revolving door that can never happen.
Cheaper is relative. Those double door systems need a lot more space if designed for many people (where you need two or three of those sets side by side), which is expensive.
And as simply someone who wants to enter a public building I prefer revolving doors. More user friendly.
More user friendly.
But so slow, that's what gets me all the time. I like moving fast around town.
Describe your double door system?
It's not a great photo, but basically you have two doors (manual, automatic, or slide) in a series, with an "airlock" space between. You open the outside door, step in the space, the outside door closes behind you, then you open the inside door and step into the building.
Perhaps because I'm far more used to them, they seem more efficient to me.
PS. This system is used in Germany too, but in very few spaces. I've seen it mostly in restaurants.