What is the purpose of revolving doors?

Answer 1

Revolving doors are chosen by architects as a space efficient and energy efficient way of allowing large amounts of foot traffic to enter a building. As the door revolves there is a constant seal between the doors and the surrounding walls preventing unwanted heat loss and pressure differences (or wind). To achieve the same effect using automatic sliding doors, you would need two sets of doors in parallel to form a wind lobby which can take up a large amount of the main entrance to a building, as well as not always effective (eg if both sets of doors are open at the same time). Revolving doors are also designed so the door leaves can be unlocked and rotated to an open position. This is so traffic can still enter and exit in the event of a power failure. Some even have a rechargable backup battery. Revolving doors are expensive, costing $50,000 - $250,00 USD complete. Compared to $2000 - $5000 USD for automatic sliding doors. Revolving doors do not latch to an opposite door. They are attached to a fixed point and thus only spin in the area given to them. However, they can be slammed into a person or object. So next time you use one, look before you spin the door.