Portable Air Conditioners: Glossary of Terms For Buyers

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Knowing the basics of portable air conditioners and the most common terms makes understanding them easier.

Here is a brief list of key terms you’re most likely to encounter when researching portable air conditioners.


BTUs stand for British Thermal Units.

This is probably the most important term for buying a portable air conditioner and the first spec you’ll see listed when shopping for a unit.

It refers to the standard unit of measurement that summarizes the size of a room or space that it should be used for (e.g., square feet). Air conditioners don’t simply blow cold air into a space with warm air. They cool the air.

By definition, BTUs refers to the energy required to raise the temperature of one pound of water by 1 degree Fahrenheit.

As for air conditioners, this measurement indicates how many BTUs per hour the unit can remove from the air surrounding it, which is how much cooler the room gets.

So, if you see a unit listed at 12,000 BTUs, it will remove that many BTUs per hour in the appropriate size.

Square Feet

It’s a term that’s familiar to most people.

Square feet refers to the square footage of a given space.

To measure your space (length x width), multiply the length by the width, then add them together to get the total square footage.

It’s important to decide what size of unit you want, BTU-wise, before buying one.


portable ac venting

You probably know what ventilation means, but it’s a bit more specific when it comes to portable air conditioners.

It refers to the ventilation that most portable air conditioners are equipped with.

Portable air conditioners expel hot air during the cooling process and need to be moved somewhere else than the same room.

Most portable units are ventilated through a window, but some prefer to vent them through a sliding door or a custom hole in the walls that lead outside or to an area such as a garage.

There are two types of ventilation systems: single-hose and double-hose. Double-hose systems are generally more efficient than single-hose systems.


Wattage is the amount of power required by an electrical appliance or device to operate.

Using less wattage means using less electricity.

You want an AC that consumes the least energy while providing the most cooling power.

This leads us to the next term.

Energy Efficiency Rating (EER)

portable ac terms

A portable air conditioner’s energy efficiency rating is its BTU rating over its wattage consumed.

You divide the BTU amount by the wattage, which results in the EER.

For example, A 12,000-BTU portable air conditioner consumes 1,400 watts, so its rating is 8.5 (12,000 BTU/1,400 watts.)

The higher the EER, the better the unit makes the most of its energy when running. This will lead to some significant savings on your energy bills over time.


Portable air conditioners are never completely silent.

The actual noise level of the unit is an important criterion to most people, especially those who want a unit as quiet as possible, even running on a max setting.

Because of this, it’s common to see a decibel level listed in a portable air conditioner’s specifications. The decibel level is a way to measure sound.

For example, the lowest possible sound can be heard is 0 decibels. Human conversation at a normal loudness from 3-5 feet away is around 60-70 decibels. Many portable air conditioners peak at 50-55 decibels on a maximum setting.


Humidity can be good for certain things, but when it comes to your home, it’s best to keep the humidity levels low.

This results in a more comfortable atmosphere that feels less clammy due to the drier air and prevents mold growth and moisture from damaging the wood, electronics, and several other items in your home.

Portable air conditioners act as dehumidifiers because of how they cool a room.

Part of the cooling process cycle these units go through involves removing the moisture from the air while cooling it. The result is a cooler space but also a less humid one.

Dehumidification is a common term listed on a unit’s specs. This refers to the amount of moisture the unit can remove from the air over a 24-hour period to run the entire time.


portable ac terms

Portable air conditioners remove moisture from the air when they cool a space.

Depending on the model, this creates condensation that can accumulate inside the unit. This issue can be dealt with in a few different ways.

Some units have a way to collect the condensate, allowing you to dispose of it when it gets full. This most often involves a sort of tray or bucket underneath the unit. Others come with a drainage hose that you can direct either outside or to a floor drain. These are effective and all, but not very convenient for most.

Self-evaporative portable air conditioners use condensates to cool the internal system and evaporate the rest. This is the best choice for those who want a more efficient unit and a more convenient one that doesn’t need to be constantly monitored.

Most self-evaporative models still have a drain plug, just in case some leftover condensate conditions are extremely humid.

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