Yes, it is more efficient! When it comes to energy efficiency, 220 volt is better. This is because a 110 volt AC unit taps more power than a 220 volt AC unit. However, this does not mean that it consumes more electricity. Another key factor is cost-efficiency. Although more economical rather than electrical, it can help shore up the argument for a 220 volt AC unit. A 110 volt AC unit requires a more thicker wire than a 220 volt AC unit. Reason being that both require the same amount of electrical charge to carry out a cooling effect. So for an AC unit of 110 volts to be able to absorb the intensity of such flow of current through it, it requires a thicker wire to avoid overheating. Thinner wires are more economically friendly than thicker wires.