Most Efficient Window Air Conditioners in 2023

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Products Updated January 24, 2023
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Just like the best air conditioners in any class, if you’re looking for the best energy-efficient window air conditioner, you’ll find that they strike a balance between power and efficiency and provide the convenience of easy window installation for consumers who need all three. Though they won’t be covered here, you may also want to learn about the best inverter ACs, which are specialized for hyper-accurate, efficiency-oriented automated air conditioning.

Since the energy efficiency rating in window air conditioners is measured and determined by its Energy Efficiency Ratio and Energy Star certification status, you must look for models that have good ratings. These units should also be easy to install and operate as silently as possible. Advanced models will come with features such as remote control, variable fan speeds, and smart home integration.

Keep reading our buying guide to learn more about the best energy-efficient air conditioners and what they offer.

Top Energy Efficient Window Air Conditioners

 #1   Midea U Inverter Window Air Conditioner


WHY WE LIKE IT: It is quiet in operation and can be controlled through voice. It is also energy-efficient and also has a 24-hour timer for scheduled functioning.

  • Very quiet operation
  • Can be controlled through voice
  • U-shaped design allows users to close their window
  • Difficult to install

The Midea U Inverter Window Air Conditioner is a 12 000 BTU unit that is quiet in its functioning and can be controlled through Amazon Alexa since it is also WiFi-enabled. The AC unit comes with a cooling, fan, dry mode, and an Eco mode that is perfect for users who want to save up on their electricity expenses. Its system can have airflow through a distance of up to 20 feet, and since it was also voted the most energy-efficient AC unit, users will be able to enjoy up to 35% energy savings compared to other alternatives. Unfortunately, some users complained that installing it is challenging to do.

With a noise output of only 42 decibels, this quiet window A/C unit is soft enough not to cause any disruptions when being used at night, and also because of its U-shaped design, users will be able to close down their windows to enjoy a clear field of view. The AC unit can also be set to auto mode and adjust its functioning based on the room’s temperature or controlled through the MideaAir app. While this unit has lower noise interference, it’s not a quiet portable air conditioner that is handy for traveling.

 #2  LG Energy Star LW8017ERSM-P Window-Mounted Air Conditioner


WHY WE LIKE IT: It is WiFi-enabled for voice and app control and does not make a lot of noise. It also comes with a remote and is easy to install.

  • Easily washable and removable filters
  • Is WiFi enabled for voice or app control
  • Has a check filter indicator
  • Previous users complained that the app was slow

The LG LW8017ERSM-P is a compact window air conditioner that comes with a remote and is also WiFi-enabled for control through voice or a remote. The AC unit has a noise output of up to 53 decibels and is also Energy Star certified for its low power consumption. It features three cooling and three fan speeds and is perfect for cooling rooms that are up to 550 Sq ft in size. The AC unit has a user-friendly control panel that also comes with an LED display and a removable filter that is easily accessible and washable. However, some previous users have complained that the app was slow to react.

The AC unit also comes with a 24-hour timer that can be programmed according to a user’s requirements and an auto-restart function that will have it restart with the same settings after a power outage. The air conditioner also comes with an installation kit that is easy to put together and a check filter indicator that lights up whenever its filters are due for a change.

 #3   Homelabs HME030341N 10 000 BTU Window Air Conditioner


WHY WE LIKE IT: Great for small spaces between 400 to 450 Sq ft. It comes with washable filters and has a 24-hour timer for programmed functioning.

  • Sleep mode for undisturbed night’s rest
  • 4-way louvers for good airflow
  • Has a 24-hour timer
  • Has a dated design

This Homelabs 10,000 BTU air conditioner is perfect for users who have a space of up to 450 Sq ft. It comes with a remote control for convenient operation, and is also compact. The AC unit is also Energy Star Certified, so users shouldn’t expect their electricity bills to shoot up too high once they have it installed. Those who would also like to have it on at night will likely appreciate its sleep mode, and since it also comes with a 24-hour timer, it can be programmed to operate according to a user’s scheduling. However, its dated design might scare away some users.

This AC unit has multiple cooling functions for users to choose from. These are cool, dry, fan, ECO, and sleep mode. Users will also be able to switch through all these with the remote provided, and since it only has a noise output of 54 to 59 decibels, it likely won’t cause any disturbance. The unit is very easy to install since it also comes with mounting accessories and with a louver that allows for 4-way airflow, the unit is well adapted to ensure that the whole room gets to have good air circulation.

 #4   Frigidaire FFRE063WAE 6000 BTU Window-Mounted Room Air Conditioner


WHY WE LIKE IT: It has a modern design and comes with adjustable side panels that extend for a good window fit. It also has a check filter indicator and an automatic restart function.

  • Is Energy Star Certified
  • Has a check filter indicator
  • Very modern design
  • Too noisy

This Frigidaire Window-Mounted air conditioner has a 6000 BTU rating and a modern design. It comes with a remote for convenient functioning, and weighing only 41.9 pounds, it shouldn’t be very difficult to move around. The AC unit is also Energy Star Certified, meaning it doesn’t have a very high rate of energy consumption. Since it also comes with a programmable 24-hour timer, users will be able to customize its functioning according to their schedule. The unit also comes with a sleep mode that makes it comfortable to use at night, but unfortunately, many previous users have complained that it is too noisy.

On the flip side, the AC unit also has a sleep mode that’ll have the temperature gradually decrease at night for a comfortable night’s rest. Since it also comes with adjustable side panels, users will be able to extend them to best fit their windows. The unit also has a multi-speed fan that can be set to either Auto, Low, Medium, or High, and a check filter indicator that lights up whenever its filters are due for a cleaning.

 #5   Soleus WS3-06E-201 Air Exclusive Window Air Conditioner


WHY WE LIKE IT: It has a very low noise output, so it should not cause any disruption. It also comes with a remote and has a filter change indicator to notify users whenever filters need to be replaced.

  • Very easy to install
  • Low noise output
  • Is Energy Star Certified
  • Does not have smart features

The Soleus 6000 BTU Over the Sill air conditioner is ideal for users who need something easy to install and also something that does not obstruct their window view. This air conditioner doesn’t take much time to put together since it does not require any tools or installation bracket. It also comes with a remote that can sense the temperature of its exact position and relay this information back to the AC unit to then apply the required changes. Unfortunately, it does not have any smart features like some other models in its category.

Owners shouldn’t have to worry about the noise output of this unit since it only produces about 38 decibels. Since it also comes with an auto mode, it’ll be able to choose the most efficient operating mode based on the current room temperature. The unit also features a dry mode to remove excess moisture from the air and a sleep mode that lowers its noise. The unit is also Energy Star Certified and will not consume a lot of electricity.

 #6   Whirlpool WHAW121BW 12 000 BTU Window-Mounted Air Conditioner


WHY WE LIKE IT: Its size allows it to fit compact windows, and since it also comes with a remote, operating it is very easy.

  • Great size for compact windows
  • Comes with a remote control
  • Has a 24-hour timer
  • No check filter indicator

The Whirlpool WHAW121BW is a 12 000 BTU window-mounted air conditioner that is great for small windows, as well as rooms of up to 550 Sq ft. The AC unit comes with a remote control to save owners the hassle of walking up to it to make changes. It has an airflow capacity of 270 CFM and can dehumidify the room at a rate of 2.64 pints per hour. Inside, it features a removable and washable air filter, however, it does not have a check filter indicator to alert users whenever the filter needs to be changed.

The AC unit will fit a window with a minimum width of 26 inches and a maximum of 36 inches. Its minimum window height is also about 16 inches. Its 8-way directional air louvers can also be used to direct air where it is required for good air circulation, and since it also has a 24-hour timer, users will also be able to program its functioning according to their needs.

Beginner’s Guide to Energy Efficient Window Air Conditioners

What Is an Energy Efficient Window Air Conditioner?

Energy-efficient window air conditioners are simply window-installed home air conditioners designed with a balance of performance and energy cost savings in mind. Cooling capacity in air conditioners is measured in BTUs or British Thermal Units. One BTU equals the amount of energy required to heat a pound of water by 1 degree Fahrenheit.

All home AC units have a BTU rating that indicates their output of BTUs per hour. This number indicates the square footage range that the air conditioner is designed to cool at maximum efficiency. For example, 5000 BTU air conditioners are designed to cool 100-150 square foot rooms, while 12,000 BTU units are designed to cool 450-550 square foot rooms or spaces. We do have some more guides on how to better understand AC unit BTU, like how big of a generator you’d need to run a 5,000 BTU air conditioner.

If you try to cool a space larger than the size for which your AC unit is designed, you lose efficiency, making the unit work harder and take longer to cool the area to the desired temperature, meaning higher energy costs for lesser performance. This can also be caused by a faulty A/C sensor no longer working.

Conversely, using a unit designed for a space much larger than the one you’re cooling it with means you’re wasting electricity where a smaller unit would do the job perfectly well. You’ll cool the space faster, but you’ll be adding to energy costs for no practical reason. The best 15000 BTU window air conditioner isn’t necessarily the most efficient, so it depends on your priorities.

Energy Efficient Window Air Conditioners Versus Other Air Conditioners

In general, energy efficiency in air conditioners is defined by three factors.

First, as a rule of thumb, the higher you go in BTU classes, the less efficient an air conditioner is. 5000 BTUs is the lowest BTU class that’s widely available, but they’re also by far the most efficient air conditioners in the BTU class. 15000 BTU units, by contrast, are the least efficient models that are widely available.

However, energy efficiency is further defined within BTU classes by two standardized ratings.

Energy Efficiency Ratio (EER)

The Energy Efficiency Ratio or EER rating will tell you how efficient a specific model is within its BTU class. EER is calculated by dividing an air conditioner’s BTU rating (also called capacity) by its wattage using the following formula: EER rating = BTUs x power in watts.

So, for a 5000 BTU unit that runs at 500W, the EER rating would be 10.00. For a 10000 BTU unit that runs at 1200W, the EER rating would be 12.0.

The U.S. Department of Energy recommends choosing models with EER ratings of 10.0 or higher for the best cost/performance ratio.

Energy Star Certification

Energy Star is a program run by the E.P.A. and the U.S. Department of Energy created to promote energy efficiency in appliances and electronics. An Energy Star certification on an air conditioner means that the unit is officially certified to use 10-50 percent less energy per year than a non-Energy Star model.

Most U.S. states offer rebates for purchasing Energy Star appliances, making them an even more attractive choice for ecologically and budget-minded consumers.

Therefore, besides BTU rating, the primary differences between a great window air conditioner that could be classified as “energy-efficient” and a model that isn’t designed with efficiency primarily in mind is a high EER rating and Energy Star Certification.

That said, while a 15000 BTU window unit with Energy Star certification and an EER rating of 10.0 can be said to be as efficient as a 5000 BTU Energy Star certified unit with the same EER rating, that’s only relative to their own BTU classes. Any given 5000 BTU unit will still be far more efficient and cost-effective than any 15000 BTU unit.

How Energy Efficient Window Air Conditioners Work

Whether they’re central air conditioning systems, like the Amana central air conditioner, window units, or wall-installed units, all air conditioners work the same way. Moisture and heat are removed from a room and replaced by cooled air by three main components: a compressor, a condenser, and an evaporator, using a chemical known as a refrigerant. It could be considered a high-quality evaporative air conditioner, too.

The refrigerant is cycled through the unit, where it’s transformed from a gas to a liquid. It cools the evaporator coil, and recycled air from the outside is cooled as it passes over the coil back into the room, where the cooled air replaces the warm air. The cycle repeats until the desired temperature is reached. To ensure all this properly works, make sure your unit is set up correctly within your space, like learning through our guide on how to insulate around a window air conditioner. Maintenance may be needed every to often to make sure your AC operates properly and runs efficiently, so you can learn how to perform these tasks yourself to save on professional help expenses, such as how to clean mold from air conditioner coils.

Why Should You Buy an Energy Efficient Window Air Conditioner?

If you need to cool a very large space and are concerned with energy costs or carbon footprint, you’ll want to look for a model with a high EER and Energy Star status, like the Bryant model that we feature in our Bryant air conditioner review. Many models offer more advanced features, such as remote control, built-in WiFi, and smart features like a 24-hour timer or mobile device connectivity, choosing to upgrade an easy one.

Is an Energy Efficient Window Air Conditioner Worth Buying:

  • You’re on a tight budget: For many consumers, the choice of efficiency over high performance in an air conditioner comes down to budget. Between two air conditioners with similar BTU ratings, features, and price points, the high EER and Energy Star status model will save you more on your power bill, making it the economical choice. For a more affordable alternative that’s still efficient, you can go for a tower fan instead like the model in this TaoTronics Tower Fan review.
  • You need to run an air conditioner year-round: For users who may only run an AC unit for a few weeks out of the year, efficiency has less of an impact on their yearly energy expenses than it does for users who need to run an AC unit year-round.
  • You’re concerned about your carbon footprint: If you’re an eco-minded consumer concerned primarily about your carbon footprint, a model in any BTU class with a high EER rating (10.0 or over) and Energy Star status is going to be the right choice.
  • You’re cooling a small space: If you’ve got a room under 150 square feet, you’re generally better off prioritizing efficient cooling by purchasing a basic 5000 BTU Energy Star-certified model since rooms in that size range will cool fairly quickly even with lower-performance models. You’ll save money and lower your carbon footprint in the process.

Why an Energy Efficient Window Air Conditioner May Not Be For You:

  • You’re cooling a large space with high ceilings: Rooms with high ceilings don’t circulate air, as well as rooms with average ceiling heights. An AC unit designed for 400-550 square foot rooms will have to work harder to cool a room with the same square footage but high ceilings, often negating the benefits of efficiency-oriented design. This means you may have super performance and cooling speeds with a less efficient, higher-BTU model without any significant difference in energy costs. Also keep in mind square footage goes hand in hand with AC tonnage. If you’re wondering, “Okay… so how many tons of AC do I need?” For every 600 sq. feet, it’s advised that you need 1 ton of AC.
  • You’re cooling a large kitchen: Air conditioners must work harder to cool kitchens because of the heat ovens and other appliances create. The principle that applies to high-ceiling spaces also applies here: a higher-BTU, less efficient AC unit that favors performance may be a better choice than an energy-efficient unit with less cooling power since the latter will have to work harder to cool the space, negating energy savings.
  • You’re on a bigger budget: If you’re less concerned about energy costs and price points, you may prefer a higher-performance or higher-BTU model that will cool your room more quickly and has more control options and advanced features like sleep mode, voice commands, Wi-Fi connectivity, or a 24-Hour On/Off Timer. For a unit with more precision and control, the best mini split of 2023 can target individual rooms to heat and cool.

How Long will an Energy Efficient Window Air Conditioner Last?

The average window air conditioner will last around ten years with regular use and proper window A/C unit maintenance. Many manufacturers offer warranties of up to five years, but a quality window unit, especially a highly efficient one, can last much longer than a decade with proper care.

There are a few primary factors that affect the lifespan of any home air conditioner.

Frequency of Use

An air conditioner that’s used sparingly throughout the year or used heavily for only a few weeks in summer will last longer than a unit regularly used throughout the year.

Regular Cleaning and Maintenance

Regularly cleaning an air conditioner’s reusable filter or changing disposable filters, in addition to periodic maintenance and upkeep, will significantly affect how long a unit will last. If you are concerned about maintenance, check our aluminum vs. copper AC coils page to see which is easier to maintain.

Clogged filters restrict proper airflow through an AC unit, making components work harder and increasing wear and tear. Ignoring failing parts or not attending to simple repairs will also shorten a unit’s life considerably.

Direct Sunlight

Constant exposure to direct sunlight on the body or chassis of an air conditioner heats the entire unit, forcing it to work harder to cool the evaporator coil and produce cool air, thus increasing wear and tear on the whole unit. Whenever possible, install a window air conditioner in a north-facing wall with adequate shade.

How to Choose the Best Energy Efficient Window Air Conditioner

Now that you’ve decided to purchase an energy-efficient window air conditioner, let’s take a look at the factors and features that will help you choose the right model.

Energy Efficient Window Air Conditioner Key Factors

1. How big an area can it cool?

The most efficient air conditioners on the market are in the 5000 BTU class and are designed to cool a space between 100-150 square feet. 6000 BTU models are the second most efficient class and are designed for 200-300 square foot spaces. Both are excellent choices for small bedrooms and TV rooms.

Generally speaking, the higher the BTU rating, the lower the overall efficiency of the AC unit, though within BTU classes, efficiency between specific models can be determined by EER rating and Energy Star status. Be sure to measure the space where you want to install the AC unit. The space needs to be able to fit the unit plus support its weight, which you can learn more about if you’re unfamiliar with how heavy a window air conditioner is.

2. What is its Energy Efficiency Ratio rating?

In conjunction with the BTU rating of an AC unit, the EER rating of a unit is a significant and standardized measure of its efficiency and is calculated by dividing the unit’s BTU rating by the unit’s wattage. The U.S. Department of Energy recommends air conditioners with an EER rating of 10 or over if you’re prioritizing efficiency.

3. What is its Energy Star status?

Energy Star is a joint program between the E.P.A. and the U.S. Department of Energy that promotes energy efficiency. The Energy Star symbol on any appliance in the U.S. certifies that the appliance uses a minimum of 10 percent less power than other comparable models.

Additionally, most states in the U.S. offer rebates with the purchase of Energy Star products, making them even more attractive to budget-minded consumers looking for maximum efficiency.

Best Energy Efficient Window Air Conditioner FAQs

Are window air conditioners better than portable air conditioners?

In terms of efficiency and performance, window air conditioners are better than portable air conditioners. Portable air conditioners are, as a rule, far less efficient and offer far less cooling power than even the lowest-BTU window units, making their main selling point simply their portability.

Are window air conditioners energy efficient?

Window air conditioners offer the most efficiency and best cost-to-performance ratio for small rooms 150 square feet and under. That's the size range of 5000 BTU window air conditioners, which are by far the most efficient air conditioners by BTU class, even more so than lower-BTU portable models. For very large spaces, wall-installed or central air systems may be more efficient, depending on various factors.

How do I know if an air conditioner is energy efficient?

After the BTU rating of an air conditioner, the easiest way to determine if a unit is energy efficient is to look for an EER rating of at 10.0 per the U.S. Department Of Energy's recommendation, and Energy Star certification, indicated by the presence of the Energy Star symbol somewhere visible on the unit.