How to Size Your Air Conditioner for What You Need

Finding the right air-conditioning unit size improves efficiency.

Installing a new air-conditioning unit in your home requires that you find the right size unit for your living space. You might think that the bigger the AC unit is, the better it will cool the home. This is not exactly true. Larger units tend to run on extremely short cycles, increasing energy consumption. Also, excessive noise and moisture build up in the unit can cause further issues. Properly sizing the air-conditioning unit may take the combination of several sizing methods.

Things You'll Need

• Tape measure

Instructions

1. Look at your old air-conditioning unit for its BTU load. This is usually printed on the label attached to the main unit inside the home.

2. Measure any externally facing walls that are facing north and are shaded by trees. Take a measurement of the height and length of the walls. Add the measurements together.

3. Measure any external walls that receive direct sunlight.

4. Measure the height and width of any interior walls.

5. Note whether the walls are made with or without insulation.

6. Find the ceiling height in feet, then find the area of the ceiling by taking the length and dividing it by the width.

7. Take the height and the width of each window in the home.

8. Write down how many people live in the home.

9. Write down the wattage of all lights and appliances used in the home.

10. Take these measurements to a air conditioner sales person to determine the correct size for the unit.

References

• Consumer Reports: How powerful an air conditioner do you need?
• Alpine Home Air: Selecting Air Conditioner Size
• Procter Energy: Bigger is Not Better