There are several types of motors, some are efficent, others are not. They vary in cost to manufacture. As you guessed the cheap motors use more electricity. The attic can at Lowe's or the garage fan already mentioned use 372 watts while this fan is designed to be efficient at 110 watts
https://www.amazon.com/QuietCool-QC-...gateway&sr=8-3
The cost difference annually is 7.47 vs. 11.97 current SECO rates, if you operate it as I do.