Top 7 Quietest Portable Air Conditioners in 2021 (Under 49 dB)

Quiet Portable Air Conditioners – Pros & Cons

There is a definite upside to having a quiet portable air conditioner – better sleep, less interference when talking to others or listening to media.

But is there a downside too? Potentially yes.

Here’s a look at both sides of the story.

Pros

1. Peace and Quiet. The quietest portable air conditioners are sought by those that use them in their bedrooms. Light sleepers don’t want to be woken up by loud fan noises or clanky compressor sounds.
2. Lower Energy Bills. The best use of a portable AC is for “space cooling,” the AC equivalent of a space heater. A quiet portable air conditioner allows you to turn up the thermostat on the central AC or heat pump and use the portable unit where you’re spending the time – a bedroom at night, home office during the day and living room in the evening. For example, turn up the thermostat from 72 degrees to 80 at night and keep the bedroom cool with the portable unit.
3. Benefits vs Window ACs. The window kit on a portable AC doesn’t block the view as much as a window AC does. And it looks better from the outside. Some homeowner associations ban window ACs on the front (or anywhere) of a house.

Cons

1. Cost. The quietest portable air conditioners are usually not the cheapest portable ACs. You’ll probably have to pay a bit more for extra insulation and design that helps to limit noise.
2. Weak Cooling and Fan on Some Models. The “cheap” way to keep an AC quiet is to build it with sub-par components. The unit will be quiet because the compressor and fan are weak, not really cranking out the cool air and airflow. That’s a cheaper path to a quiet AC than building it with more insulation, better vibration control and quality components designed for less noise. That’s not the case with units in our list, but it is a common failing of “quiet” portable ACs. Read reviews to find out what other consumers are saying about the models you’re considering.
3. Undersized for the Space. This is similar to the last issue, but it is more a problem with all portable ACs. Many of them don’t cool or dehumidify the amount of space they are rated for.

Does the 12,000 BTU portable air conditioner you’re considering say it will serve 400 square feet? It might, but only in warm conditions that aren’t too humid. If its hot and/or humid, it might take care of 250 to 300 square feet. This is a problem further addressed next.  

ASHRAE vs DOE SACC BTU Ratings

This is an important change in how the effectiveness of portable air conditioners is rated. It helps consumers better understand what they’re getting in this type of AC.

For decades, the American Society of Heating, Refrigerating and Air-Conditioning Engineers (ASHRAE) has tested the cooling power of many types of air conditioner.

ASHRAE does a simple test – how much heat, measured in British thermal units (BTUs), does the AC move per hour.

But there is a problem with portable air conditioners. When they expel air out the exhaust hose, negative air pressure is created in your home. This will suck in outside air from cracks around doors, windows, electrical outlets and other places that aren’t airtight.

Here’s what happens: The air in the room being cooled by the portable AC will become cooler and less humid. But the air in the rest of the house will actually become warmer and more humid. Even in the room with the AC, some outside air will creep in under and around the door. This obviously reduces the cooling power of the air conditioner.

As a result, the US Department of Energy (DOE) developed a different measurement for portable ACs and similar cooling appliances. It’s the Seasonally Adjusted Cooling Capacity (SACC) measurement that factors the type of infiltration we’ve been discussing and other issues. These measurements are shown in literature as DOE 2017 Standards, US DOE SACC, or similar.

DOE/SACC BTU measurements are typically 40% to 50% lower than ASHRAE because the BTUs of heat pulled into the house are factored, not just the BTUs exhausted.

If a portable air conditioner manufacturer doesn’t list the DOE measurement too, it isn’t being totally honest with you.

Window vs Portable AC Noise Levels

Noise is the biggest complaint users have about both types. There’s not a lot you can do except to choose one of the units on our Quietest Portable AC List above or Quietest Window AC List found here.

Window and portable air conditioners run at similar noise levels. The quietest units of both usually have inverter-type compressors that run more continuously, speeding up and slowing down to keep the temperature right at the thermostat set point. Inverter-driven window and portable ACs have noise levels in the mid-40 decibels.

Portable and window air conditioners with standard compressors have decibel ranges of about 48 to 56.

Here are a few differences between the two AC types:

• Some portable ACs have better insulation, and that helps reduce noise.
• Window units, since the back half is outside, can seem quieter from inside the house. Some users line the plastic “wings” that stretch to the window frame with foam insulation, a towel or other material to further reduce noise.
• Size: The larger any AC is, the more noise it will make. The largest portable air conditioners are 14,000 BTU models. The largest window air conditioners are 25,000 BTUs, sometimes more. So, the loudest window ACs are louder than the loudest portable air conditioners.

The bottom line, of course, is to compare units against each other that you are considering. If you are very sensitive to noise, another alternative is to upgrade to a ductless mini split AC. The compressor will be outside. The indoor unit will have a small fan to distribute cooled air, and it will be much quieter than either a window or portable air conditioner.

FAQs – Auto Evaporation and More

This section includes a few random but important topics for this AC type.

How much space will a portable air conditioner cool?

The point has been made that the room size rating for many portable ACs is inaccurate. Most are based on ASHRAE BTU ratings, not the newer, more accurate DOE ratings (see the last topic for details).

With that in mind, this table shows accurate room size ratings for this type of air conditioner.

What is Auto Evaporation?

All types of air conditioners remove both heat and moisture from the air. This is one of the remarkable benefits of this amazing technology.

That moisture has to go somewhere! In central cooling and in mini split AC systems, the water drains through a tube to the outside of your home. Window ACs drain it out the back – you’ve probably seen a window air conditioner dripping while running.

There are three options with portable air conditioners. First, they can drain the moisture into a tank that you have to empty. Secondly, a hose can be used to carry the water directly to a floor drain.

Those options are a bit of a hassle, especially having to empty a tank/bucket.

To avoid the hassle, a third option called evaporative technology has been developed. Here’s an overview of it. When refrigerant carries heat out of your living space, it gets really hot. So do the compressor and condenser coil through which the refrigerant flows.  

Evaporative technology: It takes advantage of that hot equipment. The moisture condensed out of the air is splashed or dripped onto the hot surfaces. It quickly evaporates, and the steam/mist is exhausted out of the house with the hot air. This leaves little or no condensation in the internal reservoir. No bucket to empty. No hassle.

Most portable air conditioners are evaporative, at least when in AC mode. Some will fill up with water in Dehumidification Mode, aka Dry Mode.

Dehumidification Mode: If you’re using your portable air conditioner as a dehumidifier, then you should attach the hose (or a garden hose) and run the hose to a floor drain.

How to Choose a Portable AC You Will Like

In short, this section is about how to choose the right portable air conditioner for your purposes. There are several key factors.

Choose the Right Size.

1. Go by DOE SACC ratings and not ASHRAE ratings to determine the BTU rating of the unit.

If the number of BTUs is listed but it doesn’t specify DOE or ASHRAE, consider it is ASHRAE.

2. Cut the ASHRAE BTU rating in half to get the “true” DOE SACC rating.

3. Use the Size Chart above to determine how many DOE-rated BTUs the unit should produce.

4. Buy an AC that produces at least as many BTUs as the chart shows. Going a little larger might be needed (Next).

Buy a Bigger Unit If…

• The ceilings are higher than 8 feet
• The room faces west/south
• The room is often occupied by 3+ people (dining area of a kitchen, living room)
• The room is a kitchen (ranges and ovens add heat to a room; boiling water adds humidity)
• Your house is old and drafty
• The space is poorly insulated

Add 1,000 BTUs for each that apply.

It’s easy to see that a 300 square feet room might be better served by a 10,000 or 12,000 BTU AC rather than a 9,000 BTU model.

You won’t regret buying a size bigger. That’s not a good idea with a central AC or mini split AC, but with portable air conditioners, it is OK or even recommended.  

Know your Modes

Most portable air conditioners have AC, Dehumidify and Fan-only modes. A few have Heat mode. These are performance modes.

Sleep Mode and Auto Mode are ways to use the other modes.

1. AC mode is ideal for hot or hot/humid weather. No surprise there.

2. Dehumidify or Dry mode removes moisture but not heat. Yes, the refrigerant initially takes out the heat, but it is circulated back into the room, so the air temperature doesn’t drop.

This mode is useful in damp weather that isn’t warm enough to require AC. If you live in a warm and humid climate, then you know that some winter days are clammy but not hot. In other climates, spring and fall days can be like this. Air conditioning would make the air chilly. Dry mode without AC makes the air drier, more comfortable, without making you cold.

3. Fan-only mode creates a breeze. In warm weather, it might be enough to keep you cool. When you don’t need AC or heat, it can also serve as white noise that helps you or a child sleep or blocks out distractions for work or study.

4. Heat mode can be very useful in chill weather and very cold weather.

In chilly weather, a portable air conditioner with heat can provide space heating in the room you are occupying, so that you don’t have to turn on the central heat source.

In cold weather, some rooms might not be adequately heated – especially those furthest from the furnace or heat pump air handler. A portable heat pump AC can provide supplemental heat to that room.

Consider Features

There really isn’t much difference in this regard between the quietest portable air conditioners – or any Portable ACs.

Common Features: Almost all have digital displays on the unit, a remote you can use to control all the functions, a 24-hour timer, caster wheels, optional drain hose for continuous use without having to empty a tank and at least one filter.

Additional Filters: If you have pets or if cooking odors are an issue in your home, consider a model with multiple air filters. A carbon filter is especially good for odors.

WiFi: There are a few WiFi portable air conditioners available. The RolliCool model in the list above is a WiFi/Smart portable air conditioner. Many of the major brands make a WiFi model. Browse the Brand Reviews and Buying Guides in the Research section below to find more smart portable air conditioners.

Voice Control: There are a growing number of quiet portable air conditioners that work with Amazon Alexa, Google Assistant and similar devices. These include the Midea MPF08CR81-E we listed as one of the Best Small Portable Air Conditioners.

You can find information about other voice control models in our reviews of Frigidaire, LG, Hisense and DeLonghi portable air conditioners for smart units with voice control and/or WiFi. Links to reviews of these brands are below. 

Additional Portable AC Research Sources

We’ve created an up-to-date suite of Buying Guides for major brands and for the types of portable air conditioners consumers want.

You might find these guides useful in your research. Each has comprehensive information to assist you in making a choice plus recommendations for the highest-rated portable air conditioners in each class or category.

Portable AC Brand Reviews:

Honeywell    LG    Haier  Hisense    DeLonghi    Frigidaire

Best Portable Air Concrete by Category:

Overall Best Portable ACs

Best Small Portable Air Conditioner

Best Tent Portable ACs for Camping

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