A portable air conditioner.

Think of portable air conditioners as the cooling choice of last resort. They’re better than a fan but far from a window AC.

That’s what Consumer Reports discovered in its tests of portable air conditioners. Despite their claims, these units barely get a room below sweltering, let alone the 78 degrees that’s considered the upper threshold of indoor comfort.
 
Portable air conditioners are intended for homes in which window configurations or building regulations prevent installation of window units.

“A portable air conditioner is an alternative—but not an ideal one,” says Chris Regan, who oversees Consumer Reports’ air conditioner tests. Portable units are typically bigger, noisier, and more expensive, and use more energy. In fact, retailers report that many portable air conditioners are returned each season by dissatisfied customers.

How Portable Air Conditioners Work

Unlike a window air conditioner, all the mechanical parts of a portable air conditioner are sitting inside the room you’re trying to cool. This contributes to the noise.

It’s also a reason for the less-than-capable cooling. While a window AC uses outside air to cool the coils on the outdoor part of the unit, a portable AC uses conditioned air from the room it’s sitting in to cool the mechanicals. That creates negative pressure that causes warm, unconditioned air from nearby rooms or the outdoors to flow into the room you’re trying to keep cool.  

More on ACs

And it’s debatable how portable they are. Once the hose is connected to the kit in the window (to vent it outdoors), you won’t want to move the unit. Not to mention they typically weigh 50 to 80 pounds—sometimes even more.

While they do have wheels, portable air conditioners can be difficult to roll on carpets and over raised thresholds between rooms.

They also need their space—the hose is 5- to 7-feet long, and the air conditioner must be positioned away from any walls or furniture that may block its airflow.

“There’s a consumer learning curve,” says Thomas Kelly, senior marketing director at GE Appliances. “Some consumers don’t realize that they have to vent the portable AC to the outdoors.”

Confusion in the AC Aisle

While window ACs have been subject to federal energy efficiency standards for more than 25 years, portable ACs have not. In 2016, the Department of Energy set new efficiency standards for portable air conditioners. But the standards have yet to be finalized.

Meanwhile, states, including California, Colorado, Vermont, and Washington, have adopted the new standards, and more manufacturers have begun to produce units that meet them.

The result? When you're shopping, you might see portable ACs that list a BTU rating according to the new standard—and some that list an inflated or misleading BTU rating. (BTUs or British thermal units measure cooling capacity.) And during this transition, you might see two BTU ratings listed on the box.

For example, a portable model that was formerly listed at 14,000 BTUs (called the ASHRAE rating) may now carry a DOE rating of 10,000 BTUs.

But even with this change, you still can’t compare a portable AC to a window AC where BTUs are concerned. “The DOE’s test conditions for window ACs are more demanding than those for portable ACs,” says Joanna Mauer, who tracks energy efficiency for the Appliance Standards Awareness Project. “A window AC rated at 6,000 BTUs will therefore deliver more cooling than a portable AC unit rated at 6,000 BTUs.”

How We Test Portable ACs

At Consumer Reports we test each air conditioner in a room appropriate for its claimed size. We've adjusted our testing, according to the DOE's new standard. “We now go by the DOE’s BTU rating,” says Regan. “That means we are testing each unit in a room more appropriate to its cooling capacity.”

In our AC tests, we measure how long it takes a portable air conditioner to lower the temperature in the test chamber from 90° F to 85° F. It takes at least 20 minutes—and often much longer. By comparison, the best window air conditioners can cool the room by 10 degrees in about 15 minutes or less.

If a Portable Is Your Only Choice

Install it right. All portables come with a kit that you install in a window. The kit consists of a plastic panel with connections for the exhaust hose. It can be installed horizontally in a double-hung window or vertically in a sliding window. Make sure all your connections are tight and seal any air gaps.
Get a ceiling fan. Create a breeze by running a ceiling fan—it will make it feel cooler.
Block the sun. Close the curtains and shades to keep the sun from overheating your room.

None of the portable ACs in our tests make our list of recommended air conditioners but if you have no alternative, consider one of the three highest performing models below.

Best Portable ACs from CR's Tests

Top Picks

1

Comfort
Brownout
Indoor noise high

2

Comfort
Brownout
Indoor noise high
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