Choosing the right cooling capacity of your portable AC

The size of your portable AC is very important. I recommend measuring the space(s) you will use it in and choosing a BTU capacity to match.

Understanding the room size you’re cooling will allow you to choose the most suitable portable AC. Follow these steps:

1. Measure the length and width of the room.
2. Multiply the length by the width to get the square footage.
3. Measure the ceiling height - 8 feet is standard, but older homes can be higher (I recommend adding 1000 BTU for each foot above 8 feet).

To work out the area of irregularly shaped rooms, I split the space into rectangular sections, measure, and add the square footage figures together.

I recommend checking the specs for RVs and tents to get accurate measurements.

You should be left with an accurate room size so you can choose an AC with BTU capacity to match.

BTU stands for British Thermal Unit, measuring how much heat an air conditioner can remove from a space per hour.

The BTU rating is the cooling output of the AC and should match the size of the space and the environmental conditions. Larger spaces need more BTU, and hot conditions need more BTU.

An AC with the wrong BTU capacity will either be ineffective or inefficient.

There are two commonly used variations of BTU ratings:

1. ASHRAE (American Society of Heating, Refrigerating, and Air Conditioning Engineers) BTU ratings are based on standardized testing conditions. They give a theoretical maximum cooling capacity.
2. SACC (Seasonally Adjusted Cooling Capacity) ratings by the DOE (Department of Energy) is the BTU figure that accounts for real-world conditions like humidity, insulation, cycling patterns, and heat radiating back into the room . They give a more realistic cooling capacity rating.