Depending on the type and age of the unit you currently have installed, you may be able to save a significant amount of money by replacing it with a newer, more energy-efficient unit. Systems manufactured as recently as 8 to ten years ago are up to 60% less energy efficient than systems on the market today. That means that, in many cases, a new unit can pay for itself in lower energy costs in a very short amount of time. If you are facing a large repair on an older system, it might be a good time to replace the unit instead of simply buying a few more years of time. For those who are financing a new unit, the monthly energy savings can usually offset a majority of the cost of a new system.