Central Air Conditioners and Air Source Heat Pumps If your central air conditioner is more than 10 years old, it may be time to replace with a new, high-efficiency model. If you replace with an ENERGY STAR® certified, high-efficiency model, you could cut your cooling costs by 30 percent. Central air conditioners ENERGY STAR certified central air conditioners have higher seasonal energy efficiency ratio (SEER) and energy efficiency ratio (EER) ratings and use 8 percent less energy than conventional new models. The higher the SEER, the greater the efficiency. Since sizing and proper installation of a central air conditioning system are critical to energy efficiency and home comfort, it is important to hire a qualified technician. Air source heat pumps Air source heat pumps, often used in moderate climates, use the difference between outdoor and indoor air temperatures to cool and heat your home. An ENERGY STAR certified heat pump has a higher seasonal energy efficiency ratio (SEER) and heating seasonal performance factor (HSPF) than standard models. This makes them about 8 percent more efficient than standard new models, and 30 percent more efficient than what you may already have in your home. Talk to your contractor to learn more.