How to Size a Portable Air Conditioner

Portable air conditioners are smaller air conditioning units that can be moved around between rooms and plugged into outlets. They are advantageous because they do not have to be stuck out a window because of exhaust. However, their capacity is only up to about 10,000 British thermal unit, or Btu, so the room size that can be cooled is limited. A Btu is the standard unit for measuring the capacity of a portable air conditioner. One Btu is the amount of energy required to heat one pound of water one degree Fahrenheit.

Difficulty: Moderately Easy

Instructions

Things You'll Need:

• Measuring tape

1. Measure the area of the room. For square rooms, square the length. For rectangular rooms, multiply the length time the width.

2. Estimate the capacity size for your portable AC unit using a chart that is readily available online (see Resources). For example, a room of 100 square feet would need about 6,000 Btu.

3. Adjust your estimate for the structure of the room. If it gets significant sunlight, add 1,500 Btu. If it gets negligent sunlight, subtract 1,000 Btu.

4. Adjust your estimate for the use of the room. If it will be used as a kitchen, add 4,000 Btu. If more than two people will live in the room, add 600 Btu for each person above the second living in the room. For example, if five people were sharing a room, you would add 1,800 Btu.

Tips & Warnings

• Get a portable AC unit as close to the capacity as possible. If the capacity is too small, you will burn out your AC unit faster because it is overworked. If it is too large, you will waste money on your utility bill.

References

• How to Choose an Air Conditioner
• Central AC Unit Sizing