When it comes to central air conditioning, it is important to remember the following:

• Air conditioning is generally used in the summer, when energy costs are higher.
• A central air conditioning system can be one of the largest users of energy in a home.

Reducing energy use related to central air conditioning can mean lower energy bills. Now isn’t that a refreshing idea?

How can you control central air conditioning energy usage?

There are two primary ways to control the energy usage of your central air conditioning system—reducing unnecessary usage and purchasing an energy-efficient system.

Steps you can take to reduce unnecessary usage include the following:

• Install a programmable thermostat. This allows you to set your air conditioner to a warmer temperature when you leave the house, then begin cooling a half-hour before you’re due to return. You can set up a similar arrangement for when you’re sleeping.
• Set your thermostat between 74 and 78 degrees, or at the highest temperature that is comfortable for you.

Replacing a 1970s-era central air conditioner could reduce your air conditioning-related energy consumption by 30% - 50%. When you’re ready to shop for a replacement, keep the following tips in mind:

• Choose the right size air conditioning system. One that is too large will cost more and consume more energy than a properly sized system. It also will need to cycle on and off more often, creating a less comfortable environment. A professional sales person can help you determine the appropriate size for your needs.
• Buy the most efficient model your budget will allow. Look for the ENERGY STAR^® label and be sure to read the yellow EnergyGuide label  to fully compute the cost of ownership over the unit’s lifetime.
• Consider upgrading insulation and windows or adding weather-stripping prior to purchasing an air conditioning system. Once you’ve done that, you may be able to purchase a smaller cooling system.

What makes an air conditioner “high-efficiency”?

A high-efficiency central air conditioner usually has one or more of the following features:

• A variable-speed fan, which slows the fan speed when less cooling is needed·
• High-efficiency motors, which use less energy to drive air through the fan·
• A high-efficiency compressor, which uses less energy to move the refrigerant·
• An improved heat exchanger, which more efficiently extracts heat from the air

How is energy efficiency measured?

• Air conditioners are rated in either British Thermal Units (BTUs) or tons (1 ton is equal to 12,000 BTUs). These terms measure cooling capacity—how much heat can be removed by the system per hour.
• An air conditioner efficiency rating measures the amount of BTUs removed per watt of electricity used. Energy Efficiency Rating (EER) and Seasonal Energy Efficiency Rating (SEER) are the two rating systems. SEER takes into account seasonal variations in climate.
• In the 1970s, central air conditioners had a SEER of between 4.5 and 8.0. Today, national standards for energy efficiency require a minimum SEER of 13.
• To find top energy-efficient air conditioners, look for the ENERGY STAR label. Central air conditioners with this label have a SEER of at least 14.0.