Turn your air conditioner off completely.
Work Step by Step
By doing this, you lower the temperature difference between the house and the outdoors. By Newton’s law of cooling, this lowers the rate of heat entering your house, and your air conditioner will use less electricity while you're gone. In other words, heat enters faster into a very chilly house than into a not-so-chilly house. However, will more electricity will be used to cool the house down later, than would have been used had you kept the house cool the whole time? Nope! Removing the heat that entered the house in half an hour, when it's at a higher-than-average temperature, takes less electricity than maintaining the house at the normal cool temperature setting for half an hour.