Revolving doors are amazing because the, never completely let the indoors air touch the outdoors air. This helps save a huge amount of money on heating in colder countries.
A building will always let hot air escape out through cracks or vents. This wil cause cold air to want to rush in through any gaps it can find. In large buildings, this would even pull doors open as well as cause the temperature to drop quite quickly. Both of which is solved with revolving doors.