Room/Window Air Conditioning Units

Room/Window Air Conditioning Units

Room/Window Conditioning units are often used in older structures that were designed before the invention of central air conditioning or have not been retrofitted with central air conditioning.  They can provide adequate cooling if sized, installed, and used properly, but can also be a huge energy user if not used properly.

Quick Links:
How to buy?
What are my Options?
Energy Saving Tips

How to buy?

Many people buy an air conditioner that is too large, thinking it will provider better cooling. However, an oversized air conditioner is actually less effective — and wastes energy at the same time. Air conditioners remove both heat and humidity from the air. If the unit is too large, it will cool the room quickly, but only remove some of the humidity. This leaves the room with a damp, clammy feeling. A properly sized unit will remove humidity effectively as it cools.

To figure out which size unit is best for your cooling needs:

1. Determine the square footage of the area to be cooled
2. Using the square footage and the chart below, determine the correct cooling capacity. Cooling capacity is measured in British thermal units (BTUs) per hour.

   Area To Be Cooled (square feet)	Capacity Needed (BTUs per hour)
   100 - 150	5,000
   150 - 250	6,000
   250 - 300	7,000
   300 - 350	8,000
   350 - 400	9,000
   400 - 450	10,000
   450 - 550	12,000
   550 - 700	14,000
   700 - 1,000	18,000
   1,000 - 1,200	21,000
   1,200 - 1,400	23,000
   1,400 - 1,500	24,000
   1,500 - 2,000	30,000
   2,000 - 2,500	34,000

3. Make any adjustments for the following circumstances:
   • If the room is heavily shaded, reduce capacity by 10 percent.
   • If the room is very sunny, increase capacity by 10 percent.
   • If more than two people regularly occupy the room, add 600 BTUs for each additional person.
   • If the unit is used in a kitchen, increase capacity by 4,000 BTUs.
   • Consider where you install the unit. If you are mounting an air conditioner near the corner of a room, look for a unit that can send the airflow in the right direction.

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What Are My Options?

Room air conditioners are eligible in all categories, which includes window units (with louvered sides), through-the-wall units (without louvered sides), casement models, casement slider models, reverse (heating) cycle window units and reverse cycle through-the-wall units.

Note the voltage. The standard household receptacle has a connection for a 115-volt branch unit circuit. Large room units rated at 115 volts may require a dedicated circuit. Room units rated a 230 volts may require a special circuit.

Select the unit with the highest Energy Efficiency Ratio (EER) for greater savings. The EER is the cooling capacity in BTUs divided by the watts.

Look for a unit whose filter slides out easily for regular cleaning. Clean filters help keep your unit in good working condition.

Consider a unit with controls. Controls such as a digital readout for the thermostat setting, and a built-in timer help you adjust your unit to use less energy.

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Energy Saving Tips

ENERGY STAR qualified room air conditioners use at least 10% less energy than conventional models.
ENERGY STAR qualified room air conditioners often include timers for better temperature control, allowing you to use the minimum amount of energy you need to cool your room.

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