It's a myth that leaving the AC on while you're away at work uses less
energy than turning it on when you get home. Here's why:
Heat goes to where it's not. That's why heat from outside goes into your
cooler home. With the AC off, at some point your house will be so hot it can
't absorb any more heat. When you come home and turn the AC on, the AC
removes all that heat.
But if the AC is on when you're gone, then you've turned your house into a
heat magnet. But keeping it artificially cool, there'