Those split units area lot more energy efficient than some of the other options out there. I know a lot of people are moving to them instead of the window units or even central systems. We recently installed a smart thermostat so we can keep the temp in the house high when we are not home, but then start the house cooling when we are on our way home. Some might argue that takes more energy than keeping it at a lower temp consistently, but I don't know anything about that.