The two most common types of air-conditioners are room and central air-conditioners. Room air conditioners, as the name implies, are used to only cool one room of your home. They are installed through a window or wall opening and plug into a household 120-V outlet. Although typically less efficient than central air-conditioners, room units are less expensive and are easily installed, especially in older homes, where a central systems may not exist.

Central air-conditioners are built into the home and work through your home’s central ventilation system. Much how your furnace creates hot air and then circulates it through the ducts into all rooms of the house, the air conditioner works in the same way, except the condenser unit is located outside the home and the cool air then fed into the home through an air handler and then through the ducts into various rooms.

Sizing Up

The correct size air-conditioner unit is absolutely critical to the unit working correctly and efficiently. Choosing a larger air-conditioner, thinking it will cool more square footage or cool faster is a common myth. Doing so will only result in an inefficient unit that will work harder than it needs to, resulting in breakdowns and higher energy bills. You’ll experience the same results choosing a unit too small for the cooling area.
To choose the correct size air-conditioner, whether it is a room or central unit, first consider the total square feet of the area you wish to cool. For square and rectangular rooms, multiply the length of the area by its width. For triangular areas, multiply the length of the area by the width and divide by two.

Using the square footage, determine the correct cooling capacity according to the following:

American Society of Heating, Refrigeration, and Air Conditioning Engineers (ASHRAE)

1791 Tullie Circle, N.E.
Atlanta, GA 30329
(404) 636-8400
Fax: (404) 321-5478
www.ashrae.org
ASHRAE is organized solely for the purpose of advancing the arts and science of heating, ventilation, air conditioning, and refrigeration for the public's benefit through research, standards writing, continuing education, and publications.

Air Conditioning Contractors of America (ACCA)

1513 16th Street NW
Washington, DC 20036
(202) 483-9370
Fax: (202) 234-4721
www.acca.org
The Air Conditioning Contractors of America is the most active and widely recognized organization representing contractors in the heating, ventilation, air conditioning, and refrigeration (HVACR) industry.

More for Your Money

Before purchasing a new air-conditioner, consider the unit’s energy efficiency rating. AC unit efficiency has exponentially increased during the last several years. SEER, or seasonal energy efficiency rating, is the unit’s energy efficiency rating – the higher the number, the more efficient (and the lower your bill is).

If your cooling system is more than 10 years old it most likely has a rating of 10 SEER or less. Replacing it with a more energy-efficient system can make a big impact on your energy use. In fact, experts say that for every $100 spent to cool your home with an 8 SEER air-conditioner, a 13 SEER unit would cost approximately $62, while an 18 SEER air-conditioner would cost approximately $39. To figure specific savings information for your household, use the energy calculators and software at www.energysavers.gov.

Much like hybrid cars or front-loading washing machines, the expense for a more efficient air-conditioner is initially higher but the savings throughout time are substantial. We don’t think the added benefit of being green and helping to protect Mother Earth isn’t too shabby either.

Additionally, homeowners can now receive a tax credit for purchasing energy efficient appliances. Under the The American Recovery and Reinvestment Act of 2009 signed on February 17, 2009, homeowners can claim 30 percent up to a maximum of $1,500 of the installed cost of qualifying energy efficient systems placed in service from January 1, 2009 – December 31, 2010. To qualify, the the unit must be for the taxpayer's principal residence and you must have a Manufacturer Certification Statement to qualify. All improvements made in 2009 will be claimed on your 2009 taxes (filed by April 15, 2010).

For more information on the tax credit program, visit the Department of Internal Revenue’s Web site at www.irs.gov.

Eco-Conscious Refrigerant

When purchasing a new air conditioner, be sure to ask your dealer what type of refrigerant the system uses. Air conditioners are available with the new, environmentally friendly R410A refrigerant. This chlorine-free refrigerant is better for the environment and it transfers heat more efficiently. Within the next few years manufacturers will no longer be able to use the old R22 refrigerant so servicing a system containing the old refrigerant will become more expensive.

EnergyStar Program

1-888-STAR-YES
e-mail: info@energystar.gov
www.energystar.gov
ENERGY STAR-labeled products, including heating and cooling equipment, use less energy than other products and save you money on utility bills. These products are made by all major manufacturers and are available at stores everywhere.

U.S. Department of Energy

1-877-337-3463
www.energysavers.gov
The Department of Energy provides glossary, fact sheets, and tips for several home systems and appliances.

Whether you decide a room air-conditioner or a central unit is for you, your options are plentiful. With a few guidelines, you’ll be as cool as cucumber for summers to come.