When it comes to heating and cooling large rooms efficiently, bigger fans are better. Most regular-ass fans top out at just under 5 ft in diameter, but the blades on a Big Ass Fan range from 6 to 24 ft. The size and design let them turn slowly—using less energy—while still achieving 25 times the airflow of models you might find in a warehouse

Oversized Ceiling Fans Heat and Cool Rooms Efficiently – Big Ass Fans – Popular Mechanics.