Earlier this year, the local television station WSMV Nashville Channel 4 had their old HVAC systems removed and replaced with new greener EnergyStar HVAC systems. They interviewed the owner of the installation company and he offered a few good tips on how to minimize energy usage when you have central heat and air that I thought were worth sharing.
He said you should try to avoid adjusting your thermostat very often. He also explained that, while it might seem like you are saving energy by turning your HVAC unit off when you are away for a few days, you actually end up using more energy that way. The reason for this is that, once the interior of your house is cool (or warm), it takes relatively little energy to maintain that temperature, assuming your house is properly insulated. On the other hand, once the house warms up (or cools down) when the unit is off, it will take many cycles of the HVAC to return not only the air, but also the furniture, flooring, and other items within your home to the original temperature. This will actually require more energy than having the unit running at a slightly modified temperature while you are away. He recommended turning the temperature up (or down) by about 5 degrees while you are away, unless you are going to be gone for an extended period of time.