When was the last time you considered installing a central air conditioning system?
Was it during a summer heat wave, when cool comfort seemed to be worth almost any price? If that is the case, as it is with so many people, you may not have found out that a whole new generation of air conditioning has become available in the last two or three years that is so efficient that systems use about two-thirds the energy of previous similar systems.

Why is energy efficiency important? Purchasing a high efficiency air conditioning system is a good way to protect against the higher electric rates some utilities charge during the summer when the demand for electricity is high. In other words, efficient central air conditioning, used efficiently, can save you money. It will also reduce the need for new power plants in the future.

How can you find the best system, at the best price, to suit your needs? The National Energy Bureau has identified three key components that you will want to keep in mind: size, or cooling capacity, efficiency, and price.

A central air conditioning system's cooling capacity is measured in Btu per hour, which is the amount of heat it can remove from your home as it cools the air for one hour. The cooling capacity of models available today varies from 12,000 to 60,000 Btu per hour. The higher the Btu per hour rating, the larger the living space the system can cool.

What Is The SEER Rating?

How efficiently the system does its job is another matter. Efficiency is expressed in terms of the seasonal energy efficiency ratio, or SEER. To determine the SEER, you divide the air conditioner cooling capacity by the amount of electric power it consumes, in watts (SEER = Btu per hour/watts averaged over the cooling season). An efficient central air conditioning system will have a SEER of 13.0 or higher, except for units of less than 20,000 Btu/hour, where a SEER greater than 12.0 is considered efficient. The energy savings can be substantial. A central air system with a SEER of 12.0 will use 33 percent less energy than a system with a SEER of 8.0.

When you go shopping, you will find the SEER listed on the yellow EnergyGuide label attached to each central air unit. The manufacturer (MFG), model number and seasonal energy efficiency ratio (SEER) are listed by cooling capacity (Btu/hour). The larger the SEER, the more efficient the system. A few models are available with a SEER of over 15.0. All models are listed in the ARI directories, which are on file at your local public library.

Reducing Your Cooling Needs

Here are a few tips on reducing your cooling needs:

  1. Try closing all windows and doors during daytime hours on hot days. Many homes will be cooler at the end of the day if kept closed up, and the air conditioning system will do less work when it is turned on. Keep the blinds and curtains closed, especially on the west and east windows.
  2. Don't set your thermostat too low, usually 78°F is found to be comfortable. You can save even more on your summer cooling bills by using your air conditioning only when you are in the house. If you want the house to be cool when you come home after a hot day, use a set back thermostat to turn on the system half an hour before you expect to arrive.
  3. To save energy and money, consider adjusting your thermostat a few degrees before leaving your house. Air conditioners also reduce the humidity by removing water vapor from the air as it is cooled. Some high efficiency units may be necessary in special cases. This potential problem can be avoided by identifying sources of moisture--e.g., clothes dryers, washing machines, showers--and venting them directly outside.

(Source: Department of Energy Fact Sheet)