Why does warm air blow down on you when you exit some buildings through automatic doors in the winter?

Question

Why does warm air blow down on you when you exit some buildings through automatic doors in the winter?

In: Technology

Answer 1

It’s an “air curtain”. A powerful fan blows a wall of air across the opening to reduce energy loss. Especially useful for doors that are used constantly such as supermarket entrances or a walk in cooler.