A comfortable temperature inside your home is relative to the temperature outside. For maximum comfort and to conserve energy, set your thermostat to different temperatures depending on the time of year and the time of day. Always set the fan on your thermostat to "Auto" instead of the "On" feature and use ceiling fans to increase your comfort in the rooms you use most often without having to adjust the temperature of the entire home.
In summer, the optimal temperature for energy conservation is 78 F. Set your thermostat to a temperature that makes your home feel comfortable, but that is as close to the 78-degree target as possible. Ceiling fans move the air so that the room feels cooler than the actual temperature setting and you might find that your family is comfortable at a higher temperature when the fans are on.
In winter, set your thermostat to 68 F to conserve energy. This may sound like a low temperature, but since you are wearing winter clothing, this temperature is not uncomfortable. If the air is too chilly, move the temperature up by one degree an hour to find the best temperature for your family.
If your family spends most of the day away from home, set your thermostat 5 to 10 degrees cooler in the winter and 5 to 10 degrees warmer in the summer during the day. A programmable thermostat will automatically lower your temperature when you leave and can return to your normal temperature 30 minutes before you arrive home. You will only notice the temperature change on your electric bill, since you are no longer paying for heating and cooling that you do not need.
Set your temperature up to 5 degrees higher at night in the summer and 5 degrees lower in the winter. Your body temperature lowers slightly during sleep, which means that a higher air conditioning temperature setting at night during summer will feel the same during sleeping hours as the lower setting feels during waking hours. In winter, you are covered with heavy blankets during the night, so the higher daytime heating setting is not necessary at night.