It is a common misconception that it takes more energy to heat up a cold house than it does to keep a house warm all the time. Turning down the thermostat will always save energy, as will turning up the air conditioner temperature setting. Heat moves from hot to cold, and the rate of heat transfer increases with greater temperature differences between inside and out. Smaller temperature differences between your house and outside generally means you'll lose less heat (or air conditioning) from inside the house to the outside. Therefore, you will save energy by only heating or cooling as much as necessary, for the occupants and time of day.
If your concern is comfort, or having to wait for your house to heat up or cool down after you get home, invest in a programmable thermostat - it can begin to heat or cool your home 30-60 minutes before you get home, so the temperature is just right when you arrive. Through proper use of a programmable thermostat (using the 4 pre-programmed settings) you can save about $150* every year in energy costs for a typical, single-family home.
The $150 savings assumes an 8 hour daytime setback and a 10 hour nighttime setback of 8 degrees F in winter and 4 degrees F in summer.
The Honeywell Digital/Programmable Thermostat offers the perfect blend of features, performance and value that delivers the highest degree of temperature control accuracy.