Revolving Door

architecture · engineering · buildings

Spinning doors. A revolving door has three or four doors attached to a central pole that spin around like a merry go round. As people step in between the doors, they walk with the doors to reach the other side.

Keeps air in. These doors are great at trapping hot or cold air inside buildings. When one person enters, the doors seal off the outside, so heat doesn't escape in winter and cool air doesn't leak out in summer.

Super common. You'll find revolving doors in fancy hotels, office buildings, department stores, and airports. They became popular because they're efficient and look impressive.

How it works. The door rotates around a vertical shaft in the middle of a cylinder. You step into the space between two doors and keep walking at your own pace until you've rotated around to the exit.