I did a post on the basics of Fans before, right here, today while on a job someone brought up DC fan motors. I didn't know too much about them, I know Emerson made the ECO fan that used a DC motor but I didn't know much more than that, so I looked into it. I want to share what I found out.
First DC refers to Direct Current, the motor in most fans uses AC or Alternating Current. Without getting very technical, a DC fan motor is far more energy efficient. The fans below use a DC motor that can run off your average household AC current. There are sophisticated built in electronics in a DC motor that make it possible to run on the standard AC current.
Unlike AC motors that use electricity to create a magnetic field, DC motors have their own built-in permanent magnetics, so they use 3 to 5 times less electricity.
Not every fan manufacturer has a DC fan available, Emerson who has one of, if not the best, motor available on the market makes the Midway Eco fan, shown above. Craftmade also makes a few fans with DC motors, the DC Epic, Hataway, Cortana and the Union all have DC motors.