This creates environment extremely hot and working condition worse. To cater this problem and make working condition good, these ventilators are installed.
Warm air is lighter and moves upward. These ventilatore help those warm air to go out. Hence coll air comes in from windows and other places.
It has great advantages as it doesn't require motor to spin even the slighest breeze can make wind ventilator to spin. It doesn't require huge cost in running.