Stormin Mormon wrote:
You pay for watts, not for volts. The 220v, you can use smaller wire
when
installing. Not more energy efficient.

You can use smaller wire but you would probably increase the voltage
drop across the wire.
If you compare lets say a 110V A/C that uses 10 amps on a 12 guage
wire, that same A/C using 220V would use only 5 amps on 12 guage wire.
In theory, they both use the same watts but then you factor in the
voltage drop, the 110V A/C would have twice the voltage loss than the
220V unit. The 110V unit would be working harder to cool a room. So in
a way the 220V is more efficient.