Energy Star says, for optimal cooling and energy efficiency, the coolest you should keep your house is 78° F and that’s only when you’re at home and awake. A programmable thermostat makes it easy to match your cooling needs to your schedule but you can make the adjustments manually if you don’t have one. Try the following setpoints:
• 78° F when you’re home.
• 85° F when you’re at work or away.
• 82° F when you’re sleeping.

More heat tolerant folks can experiment with the temperature, raising it one degree at a time to see how it affects your comfort and your budget. You’ll save 3 percent on your air conditioning costs for every degree you raise the temperature. If you aren’t comfortable at 78° F, lower the temperature a degree at a time. A ceiling or box fan causes a wind chill effect that enhances cooling, helping you feel comfortable at a higher temperature as long as the humidity isn’t too high.READ MORE