Have you ever worn shorts inside when there was snow outside? Or have you ever shivered on a hot summer day? Then most likely your heater or air conditioner is working too hard.
You can save lots of energy (and money) by turning the thermostat down when it's cold outside and up when it is warm outside.
Also, consider getting a programmable thermostat. This will regulate the heating or air conditioning by maintaining a preset temperature. A programmable thermostat contains a clock which allows you to set multiple temperatures for different times of the day. For example, during the summer, the thermostat can be set for 78 degrees F (25 degrees C) in the morning, then, at a later preset time, set to 85 degrees F (29 degrees C) when the family is away from home for work or school. In the afternoon, the thermostat is preset for 75 degrees F (23 degrees C) to reduce the temperature for the afternoon and evening.
This keeps the energy level down as well as your cost. It just makes sense not to waste so much energy keeping the air and heat blowing for absolutely no one to benefit by.