There are several factors that contribute to a home's ideal indoor temperature. Among them are season, outdoor humidity, geography and the general comfort of the individuals living in the house. In other words, there is no set temperature to suit the needs of every American household, but there are guidelines to help make that decision.
Where you live certainly dictates how warm or cool you keep your house throughout the year. A household that doesn't experience the frigid temperatures of the Northeast will obviously keep the thermostat set higher than a household in a warmer part of the country; a 50-degree low may feel quite cold to those who experience very mild winters, causing them to crank the heat to the 70s in the winter to feel warm. Most people prefer to be cool and comfortable in the summer, which means that the air conditioning is going to run for most of the time, but will run for much longer in warmer parts of the country.
EnergySavers.gov recommends keeping the house warmer in the summer while the house is empty during the day, and cooler when the house is occupied in the evening and at night. Generally, EnergySavers.gov recommends setting the thermostat to 25.6 degrees Cor an occupied home and in the low 80s when people aren't home.
The same rules that apply to summertime cooling apply to wintertime heating. Setting a programmable thermostat to a lower temperature while everyone is at work or at school will save energy and money during the day. The great thing about a programmable thermostat is that it can be set to increase the temperature at a specific time so the house will be warm when everyone gets home. A temperature of 15.5 or 16.6 degrees Celsius is ideal for an empty house--even lower is OK, too--and around 68 should be just right for an occupied house.
Heat or Cool for Comfort
Some folks are comfortable bundling up indoors to save money on their winter heating bills, and sleeping with the windows open to save money on hot summer nights. If that doesn't describe you, don't feel guilty. Set the thermostat to a reasonable temperature that's comfortable for everyone in the household. Older family members, plus infants and small children, will probably need a cooler house in the summer and a warmer house in the winter. That doesn't mean an extra sweater, a pair of socks and some slippers would hurt in the winter; doing what you can to use less energy and save on the utility bills is always a good idea.