Why should I consider spending substantially more for the high-efficiency units?

The difference in energy savings between a 10 SEER air conditioner—the lowest efficiency available—and a 13 SEER is 30 percent. Typically, the installer or the local serving utility can calculate your annual energy savings and you can then make a purchase decision based on, if desired, the simple savings you will realize for as long as you plan to be in the home. You may also want to consider the environmental benefits inherent in energy efficient equipment or the fact that some manufacturers of higher efficiency equipment provide other incentives, such as a more comprehensive warranty, quieter operation, better humidity control, and other features, or that some utilities provide rebates for the installation of certain higher efficiency equipment. Don’t too quickly overlook all the benefits of energy efficiency by focusing only on the system's first cost—think long term or life cycle, as they say in the building trade.