78 degrees?!?!?!? Do you want to see me pouring sweat at all times? There is no way I would keep my house at 78 degrees even in the Winter. These people who said this must not live in the South.
Energy Star recommends keeping it at 78 when you are home, 85 when you are away, and 82 when you are sleeping. Nope, nope, nope, nope!