The 6 best air conditioners of 2024, tested and reviewed
The best air conditioners are easy to use and install, quiet, and efficiently cool your space. These are the best window and portable units we tried.
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Friedrich, Midea, GE/Business Insider
Triple-digit temperatures are far too common these days. When this oppressive heat causes you to sweat with every movement, the best air conditioners can help you find a modicum of comfort. If you don't have central air, window air conditioners are your best bet, as they cool your room efficiently and fit in most single- and double-hung windows. The best portable air conditioners work in most other windows. If you're unsure which style of AC is right for your home, check out my comparison of portable air conditioners versus window air conditioners.
I tested over 20 units for this guide and interviewed several experts to find the best air conditioners. The Friedrich Chill Premier Smart Window Air Conditioner is my top pick because it cooled the test room the best and fits the broad range of windows. You can save 20% with my budget pick, the GE EZ Mount Window Air Conditioner. It didn't perform as well in the cooling tests but still did a good job and operated quietly.
Learn more about how Insider Reviews tests and researches home products.
The best air conditioners in 2024
Best overall: Friedrich Chill Premier Smart Window Air Conditioner (CCF08A10A) - See at AJ Madison
Best budget: GE EZ Mount Window Air Conditioner (AHY08LZ)- See at AJ Madison
Best energy-efficient: Midea U Inverter Window Air Conditioner ( MAW08V1QWT)- See at Amazon
Best for small rooms: Haier Window Air Conditioner (ESAQ406TZ) - See at Amazon
Best portable: LG Dual Inverter Smart Wi-Fi Portable Air Conditioner (LP1419IVSM)- See at Best Buy
Best design: July Air Conditioner - See at July
Best overall
The Friedrich Chill Premier Smart Window Air Conditioner CCF08A10A dropped the temperature the most of the I tested. The temp dropped 5.3 degrees in one hour.
The simple installation only took 30 minutes. I spent 10 minutes connecting to the app (iOS and Android.) The app works well, allowing you to control and schedule the AC from anywhere.
It is Energy Star-certified and was middle-of-the-road in energy use among the tested models. While running on high for an hour, it used 0.4 kWh.
James Brains/Insider
This is my fourth summer using the Friedrich Chill Premier on the top floor of my house, where all the heat collects. Originally, I used a portable AC to cool up there, but it wasn't getting the job done. The Friedrich does. Unless it's a sweltering day, I prefer to run the dehumidifier setting. Otherwise, it gets too cold for my comfort. The control panel doesn't seem to work anymore, but the app adjusts the settings effortlessly.
Running louder than a refrigerator, the Friedrich AC is among the loudest we tested. However, I didn't find it distracting while working; it helped drown out the outside noise. This is the best air conditioner you can buy for cooling power.
Read my full Friedrich Chill Premier Air Conditioner review.
Best budget
The GE Smart Window Air Conditioner (AHY08LZ) is relatively light at 54 pounds and simple to install. I had it up and running within 20 minutes of opening the box, and it fit my slender 24-inch-wide window frame.
More importantly, it's a workhorse. In my 650-square-foot test room — nearly twice what the unit is rated for — the GE decreased the temperature by more than 3 degrees in an hour. It did this while remaining fairly quiet, registering only 55 decibels on high, which makes it suitable for bedrooms and home offices.
James Brains/Insider
Its control panel shows the temperature in large, easy-to-read numbers and automatically dims to keep light to a minimum if you use it in the bedroom at night. The face also features adjustable louvers that allow you to send cool air precisely where you want it.
The GE has WiFi connectivity and can be operated remotely, but I could not get it to connect. Since I tested this unit, GE has updated to the new SmartHQ app, which has much better customer ratings in Google Play and the App Store than the previous app.
Best energy-efficient
The Midea U Inverter Window Air Conditioner (MAW08V1QWT) has a unique U-shaped design that offers more secure installation when combined with the included support bracket — hardware that rarely comes with AC units — and allows you to open and close the window to let in fresh air.
It's the first window AC to receive the Energy Star "Most Efficient" certification and remains one of only a few models to receive that designation — another is the LG Dual Inverter AC, our pick for the best AC for large rooms.
The Midea U uses inverter technology to achieve such impressive efficiency numbers. Inverter compressors have variable-speed motors that adjust to maintain the desired temperature. This constant low-level operation is more efficient than cycling high output on and off like traditional units do. The Midea U consumed 9.6 kWh over a 24-hour period, which works out to 0.4 kWh each hour.
James Brains/Insider
Installation was quick, though the instructions could be a bit clearer. Still, I had the unit up and running within 25 minutes of opening the box. Connecting to the smart app was also quick, and I could control the Midea U with my voice using Alexa.
I was impressed with how quietly the AC runs. The sound meter registered 48 decibels while operating on its highest setting.
The only reason the Midea U isn't the top overall pick is its lukewarm performance in my cooling tests. It only decreased the temperature of the test room by 1.7 degrees in the first hour — comparable to my budget pick.
Read my full Midea U-Shaped Air Conditioner review.
Best for small rooms
The Haier ESAQ406TZ Window Air Conditioner registered the lowest noise output of any unit I tested. On low, the sound meter measured 41.9 decibels, almost as quiet as a library. Even on high, it was slightly louder than a normal conversation at 51.4 decibels. Coupled with the low Btu output, this is the ideal unit for bedrooms and home offices.
Installing the Haier AC was relatively easy and required no special steps. The process took about 25 minutes.
James Brains/Insider
The Haier was in the middle of the pack in cooling. It lowered the room's temperature by about 2 degrees in one hour. This is impressive, considering it was one of only two units with less than 8,000 Btu that I tested. (The other, the GE AHQ06LZ, did much worse.) I like that there are multi-directional vent adjustments to send the cool air where you want it most. These features make the Haier my pick for the best air conditioner for small rooms.
Lastly, it's Energy Star-certified, which aligns with my experience with it. After an hour, it used 0.3 kWh of electricity. It has an estimated yearly energy cost of about $52, according to government data.
Best portable
Portable air conditioners have their benefits: portability and the ability to work with any outside opening. However, they vastly underperform compared to window ACs, and no portable models are Energy Star certified. While window AC units suck in hot air and vent it directly out the window, portable ACs rely on a long tube to carry air from your room to the outside. Along the way, heat radiates from the tube and stays in the room, and the pressure differential from removing the hot air attracts more hot air. It takes a lot more energy (and money) to cool a room with a portable AC than a window AC.
If you have a window that will accommodate it, I always recommend a window unit over a portable model. If that's not an option, however, the LG Dual Inverter Smart Wi-Fi Portable Air Conditioner (LP1419IVSM) is your best bet.
James Brains/Insider
The LG portable AC is the top pick from in my guide to the best portable air conditioners because it's quieter and more efficient than most portable models due to its dual-inverter compressor. It'll take about double the time to cool a room than a window unit, but it's very easy to install and use.
After an initial 30-minute installation time (including connecting to the app), it was super simple to move from room to room. Thanks to its handles, smooth casters, and a dedicated slot for the window slider when in transport, it only took about a minute to reinstall it in a new room. We like that it can accommodate a wider range of windows than the other units in this guide.
It's Alexa-enabled and also has smart capabilities through the LG ThinQ app (iOS and Android), which lets you schedule when the unit runs.
Read our full LG portable air conditioner review and check out our guide to the best portable air conditioners.
Best design
Honestly, most air conditioners are boring-looking at best and an eye sore at worst. The July Air Conditioner is a major exception. It features an aesthetically pleasing, minimalist design and six cover options to match your home's decor. You can also add plexiglass side panels for extra natural light.
Installation of the July AC was a breeze. First, you install the unit's border and side panels, and then you pop the AC in. The process took 15 minutes, and another five minutes to download and connect to the July app (available for iOS and Android). In addition to the usual array of features, the app lets you set a schedule. I paired it with Amazon Alexa for voice control.
James Brains/Business Insider
Performance-wise, the July air conditioner was a little better than average. It decreased the room temperature by two degrees in an hour, which is good considering the test room was 2.5 times as big as what it's rated for.
The noise and energy use were middle-of-the-pack. In an hour, the July used 0.5 kWh. Based on average electricity costs, it will cost you about $62 to run for eight hours a day all summer. The unit was about 55 decibels on high speed or a little louder than a refrigerator. Overall, this is the best air conditioner you can buy if aesthetics are a major consideration.
Read my full July Air Conditioner review.
What to look for in an air conditioner
James Brains/Insider
When shopping for an AC, there are four primary factors to consider: type of AC, Btu, energy efficiency, and extra features. Below I detail more about what to look for in each category:
Types of air conditioners
There are four primary types of air conditioners: window units, portable air conditioners, ductless mini split, and through-the-wall units.
- Window ACs: This guide primarily deals with window air conditioners because they're relatively inexpensive, easy to install, and can be used by both renters and homeowners. I think this is the best for most people.
- Portable ACs: You may consider a portable air conditioner if you don't have windows that will fit a traditional unit. However, they're less efficient at cooling than window units. Read more about the best portable air conditioners and when you should buy a window AC vs a portable AC.
- Ductless mini-split air conditioners: Mini-splits are a more permanent cooling solution. They feature a wall unit connected to a compressor that sits outside your home. We only recommend this AC type for homeowners who do not want to invest in a full HVAC system.
- Through-the-wall ACs: These units should only be considered when you're aiming to cool a room with an exterior wall that does not have windows, or if this is the type of unit already installed in your home or rental.
Btu
Btu is short for British thermal units. One Btu is equal to the amount of heat needed to raise 1 pound of water by 1 degree Fahrenheit. In cooling, Btu is used to measure how much heat is removed from a room. The more Btu per hour an air conditioner is rated for, the better job it does cooling. That said, you shouldn't just leap to buy the air conditioner with the highest Btu possible. For maximum cooling and efficiency, you need a unit that isn't too big or too small for your room size.
If you get a unit that is too big for your room, it will cool too quickly without removing the moisture, which will create a cold, clammy environment. Alternatively, an AC that is too small will be overworked, boosting your energy bills. Use the table below (from the Energy Star website) to determine the best air conditioner Btu for your room size:
Room size | Cooling power needed |
100 to 150 square feet | 5,000 Btu |
150 to 250 sq. ft. | 6,000 Btu |
250 to 300 sq. ft. | 7,000 Btu |
300 to 350 sq. ft. | 8,000 Btu |
350 to 400 sq. ft. | 9.000 Btu |
400 to 450 sq. ft. | 10,000 Btu |
450 to 550 sq. ft. | 12,000 Btu |
550 to 700 sq. ft. | 14,000 Btu |
700 to 1,000 sq. ft. | 18,000 Btu |
1,000 to 1,200 sq. ft. | 21,000 Btu |
1,200 to 1,400 sq. ft. | 23,000 Btu |
1,400 to 1,500 sq. ft. | 24,000 Btu |
1,500 to 2,000 sq. ft. | 30,000 Btu |
2,000 to 2,500 sq. ft. | 34,000 Btu |
Your Btu needs will be greater if the room has a ceiling more than 8 feet high, is very sunny, is regularly occupied by more than two people, or it's a kitchen.
It's common for model numbers for the same units to vary by one or two digits. This usually denotes different Btu ratings and colors, so choosing a model number that reflects the Btu rating right for your room is crucial.
Energy efficiency
Air conditioners have come a long way in terms of energy efficiency, but you'll want to look for a few things that will ensure you're getting the most efficient unit possible:
- Energy Star certification: The easiest way to determine if you're getting an energy-efficient appliance is to look for Energy Star certification. This program is run by the US Department of Energy and EPA to promote energy efficiency. "Any window AC model that earns the Energy Star label is independently certified to save energy, save money, and help protect the climate," says Enesta Jones, a spokesperson for the US Environmental Protection Agency (EPA). The EPA oversees the Energy Star program.
- CEER: If you want to get deeper into the numbers, look at a unit's CEER. "The CEER, or Combined Energy Efficiency Ratio, is a measure of energy efficiency for a room air conditioner," Jones says. "The higher a room air conditioner's CEER value, the more efficient the room conditioner is when comparing across models with the same cooling capacity." The CEER is measured by dividing the Btu output by the amount of energy consumed both while the unit is running and while it's in standby mode.
- kWh: Finally, consider kilowatt-hours (kWh). This is a unit of energy that most electricity utilities use to measure your power use, and it's what I use to measure the energy consumption of the air conditioners I test.
Extra features and other considerations
Below are some other features and qualities you might consider when shopping for an AC:
- WiFi connectivity: Some ACs have WiFi connectivity that allows you to use your phone to schedule and control the unit remotely. You can crank the AC before you get home or turn it off after you leave to save energy. Many pair with smart speakers for voice operation. Smart ACs don't always work as advertised. In my reviews, I note if smart functions work well. In general, though, you're probably better off using a remote control, offered with all ACs in my guide.
- Noise: All AC units make some noise, but if you're installing a unit in a bedroom, you want to keep sound output consistent and at a minimum. I note the noise output of the picks above.
- Window access: Some newer AC models (notably the Midea U) offer window access even when the AC is installed. This is a nice option if you live somewhere where the weather fluctuates a lot during the season. Another model, the July Air Conditioner, has the option to add clear side panels to let in more natural light.
How we test air conditioners
James Brains/Insider
I tested 14 window units and consulted Enesta Jones, an EPA spokesperson, to determine the best air conditioners. My picks are energy-efficient, have helpful features, and performed well in my tests.
Here is how I test the main attributes I look for:
Installation: You'll probably only install and uninstall your AC once a year, but it can significantly impact your unit's performance. I timed how long it took to install each model, noted if I needed special tools, and assessed how easy it was to uninstall. I also looked at the window sizes each air conditioner would fit. Most will fit windows 27 to 36 inches wide.
Cooling: I set up a digital thermometer on the opposite side of a 650-square-foot room from the air conditioner and determined its cooling capabilities by comparing the temperature before and after running the AC on its highest setting for an hour.
Noise: I took a decibel reading using a sound meter positioned 6 feet away from the AC running on high. I also noted any jarring sounds as the compressor turned on and off.
Air quality: Using an air quality monitor, I measured the particulate matter and volatile organic compounds in the air before and after running the AC for an hour. I noted any significant changes in air quality in my reviews, but the air quality never entered the "harmful" range during the tests, and I don't weigh this category heavily.
Power use: Using a smart plug, I measured how many kWh of power each unit used when on high for an hour.
Extras: Almost all ACs have fan and dehumidifier modes, a window installation kit, a delayed on/off function, and a remote control. These are the basics. I give extra points if a unit has foam seals, curtain insulation, WiFi connectivity, or other bonuses.
Air conditioner FAQs
James Brains/Insider
How can you use your air conditioner efficiently?
Jones recommends you keep the unit level, circulate cool air with a fan, keep heat-producing objects away from the AC thermostat, and use a low fan speed on humid days. You can also save on energy costs by installing your air conditioner in a shaded spot and keeping the thermostat as high as is comfortable.
Can I use an air conditioner in a room without windows?
Yes. However, the hot air your AC produces needs a way out of the room. Otherwise, you'll cancel out your unit's cooling effects. If you don't have a window, pick an AC that sends its hot air out the back. You can install these in an exterior wall.
A portable unit gives you more options since the opening to the outdoors only needs to be as large as the exhaust hose.
Which is better: a portable air conditioner or a window/room air conditioner?
I cover this topic extensively in my comparison of portable air conditioners vs window air conditioners, but the short answer is: window units, for most people.
According to Jones, window ACs are more efficient than portable units, which aren't part of the Energy Star program. I found this to be true in my testing. The most efficient portable AC I tested used 60% more energy than the top window pick.
Portable ACs are great in spaces where there isn't a window that can support a window air conditioner. But, in general, if you have a single- or double-hung window, the best air conditioner is a window unit. It will offer better cooling and efficiency along with lower upfront and long-term costs.
What should you do if your air conditioner is too powerful for your room size?
If your AC has too much Btu for your room, it will cool faster than it can dehumidify, creating an uncomfortable, clammy environment. Consider purchasing a dehumidifier to remove access moisture or replacing the AC with a more suitable unit. Another solution is increasing the space you are cooling. You can do this by keeping internal doors open.
James Brains/Insider
Pros: Long warranty on the sealed refrigerant system, WiFi connectivity, fits a broad range of window sizes, performed the best in our cooling tests
Cons: Operates loudly, the control panel stopped working
The Friedrich CCF08A10A Chill Premier Smart Window Air Conditioner dropped the temperature the most of the 14 models we tested in our 650-square-foot testing room. The temp dropped 5.3 degrees in one hour.
The simple installation only took 30 minutes. I spent 10 minutes connecting to the app (iOS and Android.) The app works well, allowing you to control and schedule the AC from anywhere.
It is Energy Star-certified and was middle-of-the-road in energy use among the tested models. While running on high for an hour, it used 0.4 kWh.
This is my third summer using the Friedrich Chill Premier on the top floor of my house, where all the heat collects. Originally, I used a portable AC to cool up there, but it wasn't getting the job done. The Friedrich does. Unless it's a sweltering day, I prefer to run the dehumidifier setting. Otherwise, it gets too cold for my comfort. The control panel doesn't seem to work anymore, but the app adjusts the settings effortlessly.
At 56.3 decibels on high (louder than a refrigerator), the Friedrich AC is among the loudest we tested. However, I didn't find it distracting while working; it helped drown out the outside noise. For most people, this is the best air conditioner you can buy for cooling power.
Read our full Friedrich Chill Premier Air Conditioner review.
James Brains/Insider
Pros: Energy Star-certified, performed well in cooling tests, easy to install, quiet operation
Cons: Unimpressive CEER rating, minimal warranty
The GE Smart Window Air Conditioner (model AHY08LZ) features a relatively light weight of 54 pounds and is simple to install. I had it up and running within 20 minutes of opening the box, and it fit my slender 24-inch-wide window frame.
More importantly, it's a workhorse. In our test room of 650 square feet — nearly twice what the unit is rated for — the GE could decrease the temperature by more than 3 degrees in an hour. It did this while remaining fairly quiet, registering only 55 decibels on high, which makes it suitable for bedrooms and home offices.
Its control panel shows the temperature in large, easy-to-read numbers and automatically dims to keep light to a minimum if you're using it in the bedroom at night. The face also features adjustable louvers that allow you to send cool air precisely where you want.
The GE has Wi-Fi connectivity and can be operated remotely, but I could not get it to connect. GE has updated to the new SmartHQ app since I tested this unit. It has much better customer ratings in Google Play and the App Store than the previous app.
James Brains/Insider
Pros: Unique U-shaped design, Energy Star "Most Efficient" certification, easy to install in a wide array of windows, comes with a support bracket, quiet 48-decibel operation, smart connectivity that works well
Cons: Can only change airflow direction horizontally
The Midea MAW08V1QWT U Inverter Window Air Conditioner has a unique U-shaped design that offers more secure installation when combined with the included support bracket — hardware that rarely comes with AC units — and allows you to open and close the window to let in fresh air.
It's the first window AC to receive the Energy Star "Most Efficient" certification, and remains one of only a few models to receive that designation — another is the LG Dual Inverter AC, our pick for the best AC for large rooms.
The Midea U uses inverter technology to achieve such impressive efficiency numbers. Inverter compressors have variable-speed motors that adjust to maintain the desired temperature. This constant low-level operation is more efficient than cycling high output on and off like traditional units do. The Midea U consumed 9.6 kWh over a 24-hour period, which works out to 0.4 kWh each hour.
Installation was quick, though the instructions could be a bit clearer. Still, I had the unit up and running within 25 minutes of opening the box. Connecting to the smart app was also quick and let me control the Midea U with my voice using Alexa.
I was impressed with how quietly the AC runs. The sound meter registered 48 decibels while operating on its highest setting.
The only reason the Midea U isn't our top overall pick is its lukewarm performance in our cooling tests. It only decreased the temperature of our 650-square-foot room by 1.7 degrees in the first hour — comparable to our budget pick.
Read our full Midea U-Shaped Air Conditioner review.
James Brains/Insider
Pros: Good cooling for its size, quiet operation, easy installation, seemed to improve air quality during testing, Energy Star-certified, multi-directional vent control
Cons: Requires a window width of at least 26 1/16 inches, minimal/standard warranty
The Haier ESAQ406TZ Window Air Conditioner registered the lowest noise output of any of the units in our testing. On low, our sound meter measured 41.9 decibels, which is almost as quiet as a library. Even on high, it was only slightly louder than a normal conversation at 51.4 decibels. Coupled with the low Btu output, this is the ideal unit for bedrooms and home offices.
Installing the Haier AC was relatively easy and required no special steps. The process took about 25 minutes.
The Haier was in the middle of the pack in cooling. It lowered the room's temperature by about 2 degrees in one hour. This is impressive, considering it was one of only two units with less than 8,000 Btu that I tested. (The other, the GE AHQ06LZ, did a much poorer job.) I like that there are multi-directional vent adjustments to send the cool air where you want it most. These features make the Haier our pick for the best air conditioner for small rooms.
Lastly, it's Energy Star-certified, which aligns with my experience with it. After an hour, it used 0.3 kWh of electricity. It has an estimated yearly energy cost of about $52, according to government data.
James Brains/Insider
Pros: Good performance in our cooling tests, quiet operation, certified Energy Star "Most Efficient," Wi-Fi connectivity with support for Alexa and Google Home, can be controlled remotely with a smartphone app
Cons: Pain to install, underwhelming one-year warranty, only works in windows at least 27-inches wide
This LG unit was one of the best in our cooling tests, dropping the temperature in a 650-square-foot room by 3.3 degrees in one hour. It was also one of the quietest, registering just 53 decibels on high.
LG was the first to use inverter technology in its air conditioners. The dual-inverter compressor of the LG LW1517IVSM Dual Inverter Smart Window Air Conditioner helped it earn the rare Energy Star "Most Efficient" certification.
I've used this AC on the ground floor of my home for four years now. Even on the hottest days, the LG LW1517IVSM keeps us cool. It remains quiet enough to facilitate normal conversation.
Installation was difficult, however. It took me two hours and included steps like removing and reinstalling parts from the unit. Uninstalling it for the winter was a task. Usually, I can carry air conditioners on my own, but I had to enlist the help of my kid when putting it in storage.
The LG can be used with Amazon Alexa and Google Assistant. You can also use LG's SmartThinQ app (iOS and Android) to schedule the unit and perform other remote operations.
Read our full review of the LG LW1517IVSM Air Conditioner.
James Brains/Insider
Pros: Can be controlled and scheduled using your phone, voice control, easy to move, performed well in cooling tests, fits a wide array of window types and sizes
Cons: Set up took longer than others, one-year warranty, terrible energy efficiency compared to window ACs
Portable air conditioners have their benefits: namely portability and the ability to work with any outside opening. However, they vastly under perform compared to window ACs and no portable models are currently certified by Energy Star. While window AC units suck in hot air and vent it directly out the window, portable ACs rely on a long tube to carry air from your room to the outside. Along the way, heat radiates from the tube and stays in the room, so it takes a lot more energy (and money) to cool a room with a portable AC than a window AC.
If you have a window that will accommodate it, we always recommend a window unit over a portable model. If that's not an option, however, the LG LP1419IVSM Dual Inverter Smart Wi-Fi Portable Air Conditioner is your best bet.
The LG portable AC is our top pick from our guide to the best portable air conditioners because it's quieter and more efficient than most portable models due to its dual-inverter compressor. It'll take about double the time to cool a room than a window unit, but it's very easy to install and use.
After an initial 30-minute installation time (including connecting to the app), it was super simple to move from room to room. It only took about a minute to reinstall it in a new room thanks to its handles, smooth casters, and a dedicated slot for the window slider when in transport. We like that it can accommodate a wider range of windows than the other units in this guide.
It's Alexa-enabled and also has smart capabilities through the LG ThinQ app (iOS and Android), which lets you schedule when the unit runs.
Read our full LG portable air conditioner review and check out our guide to the best portable air conditioners.
James Brains/Insider
I tested 13 window units to determine the best air conditioners. I also consulted Enesta Jones, a US Environmental Protection Agency (EPA) spokesperson. The EPA oversees the Energy Star program. Our picks are energy-efficient, have helpful features, and performed well in our tests.
Here is how we test the main attributes we look for:
Installation: You'll probably only install and uninstall your AC once a year, but it can significantly impact your unit's performance. I timed how long it took to install each model, noted if I needed special tools, and assessed how easy it was to uninstall. I also looked at the window sizes each air conditioner would fit. Most will fit windows 27 to 36 inches wide.
Cooling: I set up a digital thermometer on the opposite side of a 650-square-foot room from the air conditioner and determined its cooling capabilities by comparing the temperature before and after running the AC on its highest setting for an hour.
Noise: I took a decibel reading using a sound meter positioned 6 feet away from the AC running on high. I also noted any jarring sounds as the compressor turned on and off.
Air quality: Using an air quality monitor, I measured the particulate matter and volatile organic compounds in the air before and after running the AC for an hour. I noted any significant changes in air quality in our reviews, but the air quality never entered the "harmful" range during the tests, and I don't weigh this category heavily.
Power use: Using a smart plug, I measured how many kWh of power each unit used when on high for an hour.
Extras: Almost all ACs come with fan and dehumidifier modes, a window installation kit, a delayed on/off function, and a remote control. These are the basics. We give extra points if a unit comes with foam seals, curtain insulation, WiFi connectivity, or other bonuses.
James Brains/Insider
How can you use your air conditioner efficiently?
Enesta Jones, a spokesperson for the EPA, which manages the Energy Star program, recommends you keep the unit level, circulate cool air with a fan, keep heat-producing objects away from the AC thermostat, and use a low fan speed on humid days.
You can also save on energy costs by installing your air conditioner in a shaded spot and keeping the thermostat as high as is comfortable.
Can I use an air conditioner in a room without windows?
Yes. However, the hot air your AC produces needs a way out of the room. Otherwise, you'll cancel out your unit's cooling effects. If you don't have a window, pick an AC that sends its hot air out the back. You can install these in an exterior wall.
You have more options with a portable unit since the opening to the outdoors only needs to be as large as the exhaust hose.
Which is better: a portable air conditioner or a window/room air conditioner?
We cover this topic extensively in our comparison of portable air conditioners vs window air conditioners, but the short answer is: window units, for most people.
According to Jones, window ACs are more efficient than portable units, which aren't part of the Energy Star program. We found this to be true in our testing. The most efficient portable AC in our tests used 60% more energy than our top window pick.
Portable ACs are great in spaces where there isn't a window that can support a window air conditioner. But, in general, if you have a single- or double-hung window, the best air conditioner is a window unit, which will offer better cooling and efficiency along with lower upfront and long-term costs.
What should you do if your air conditioner is too powerful for your room size?
If your AC has too many Btu for your room, it will cool faster than it can dehumidify, creating an uncomfortable, clammy environment. Consider purchasing a dehumidifier to remove access moisture, or replace the AC with a more suitable unit.
Another solution is increasing the space you are cooling. You can do this by keeping internal doors open.