7 Most Energy Efficient Window Air Conditioners – (Reviews & Guide 2019)

This post examines the most energy efficient window air conditioners by reviewing a series of window air conditioners currently available on the market. Energy efficiency is determined by several factors, including power usage, the size of a room, and extra features that improve the unit’s overall efficiency.

There is also the official seal of approval, known as ‘Energy Star Rating.’ The energy star rating is an American government program that was put together in 1992 by the Environmental Protection Agency (EPA). Any products that have this rating comply with the energy standards laid out by this program. So, without further ado, let’s examine some of the best energy star window air conditioners.

7 Most Energy Efficient Window Air Conditioners Reviews

1. Frigidaire FFRA0511Q1 Window Air Conditioner

The Frigidaire FFRA0511Q1 is a wonderfully economic example of a high-efficiency window air conditioner. It uses a standard 115-volt plug, so it can be powered by the same voltage of electricity as most other appliances in your home.

While it’s not officially energy star certified, it stills boasts an energy efficient rating (EER) of 9.7. This is still considered to be an energy efficient model.

The purchase price and the estimated yearly cost both highlight the fact that it doesn’t consume too much energy: for a mere $46 running costs a year, it’s clear that the Frigidaire FFRA0511Q1 is not only a cheap window air conditioner but also a cost and energy efficient way of cooling a 150 square foot room.

If the energy consumption weren’t impressive, you would soon see this reflected in your utility bill. Moreover, its 5000 BTU output allows this window air conditioner to start up without using a lot of power.

At the same time, it keeps the air dry by dehumidifying 0.8 pints of water per hour. The antibacterial filter also keeps the air clean by removing microbes, so all in all this model gives you a lot of bang for your buck and can be deemed energy efficient.


  • Low power start-up
  • Includes mounting kit
  • Great price


  • Not Energy Star Certified


2. Kenmore Smart 04277107 Room Air Conditioner

The EPA has given the Kenmore Smart 04277107 their official seal of approval. That’s right: it is energy star certified. To be energy star certified means that a product has the government’s seal of approval with regards to its energy consumption. Thus, any customer who is concerned about their energy use or the environment, in general, can rest assured that this window air conditioner is officially deemed to be energy efficient.

Moreover, the Kenmore Smart boasts a lot of features that make it even more conducive to saving energy in the home.

For example, it features a Smart AC app that allows you to hook up your smartphone to your window air conditioner and monitor it from anywhere. As long as you have Wi-Fi where you are, you can log on to the app and check the specifics of your air conditioner when you’re at work, out shopping, or hanging out with friends.

This allows you to save even more energy and money because you can tailor your home’s temperature to suit your routine. If no one is at home, you can increase the temperature by a few degrees or even switch the device off. Then, you can program it to come on again shortly before a household member arrives home, so it’s nice and cool for their arrival.

Evidently, the Kenmore Smart window air conditioner has been designed with the modern, technologically- savvy consumer in mind. It can cool a room up to 500 square feet and is even compatible with Alexa. Smart technology is conducive to an energy-saving lifestyle, so it’s no surprise this model is a little bit more expensive than others — you’ll undoubtedly save money in the long run. It’s also one of the quietest window air conditioners on the market.


  • Can be used with Amazon Alexa and smartphones
  • Energy Star certified


  • Price a bit higher than other energy efficient window air conditioners


3. Koldfront WAC10002WCO Window Air Conditioner

The Koldfront WAC12002WCO boasts a wide variety of energy saving features and an impressive BTU rating of 10,000 BTUs. For a purchase price of around $400 to $500, it initially seems that this model is more expensive than the average window air conditioner and almost the same price as casement window air conditioners.

However, the cost usually goes up in proportion to the BTU rating. The higher the BTU, the higher the price. This is because a higher BTU window air conditioner can cool a bigger room. This model can cool up to 550 square feet, so it is suitable for large dining rooms and living room spaces. The price is still reasonable when you consider this factor.

The Koldfront WAC12002WCO is a great choice for homeowners who wants to reduce their energy consumption. It is energy star rated and has an impressive energy efficiency ratio of 12.0. The energy saving features include a check filter alert, thermostat, energy saver mode, and sleep mode. The check filter alert ensures the filter will always be changed when necessary, thereby ensuring it runs at optimum capacity and doesn’t drain energy. The thermostat allows you to control and monitor the temperature, so it doesn’t run consistently even when the room is cool enough.

The energy saver mode turns off the compressor when the temperature matches your requirements and uses the fan to keep things cool until it goes above the set temperature. This ensures that the compressor isn’t running unless it’s necessary. The sleep mode adjusts the temperature by 2 degrees while you’re asleep, and will return to the set temperature within six hours.


  • Energy Star certified
  • Uses a standard 115v plug
  • Energy saving features


  • Running costs higher than other energy efficient models with lower BTUs


4. LG LW1816HR Window Air Conditioner

At 126 pounds, the LG LW1816HR is one of the heaviest energy-saving air con on this list. If you’re installing the system yourself, you’ll need help with this one! Still, it has many positive attributes with regards to energy efficiency.

The first thing you’ll notice is that it’s a multifunctional AC (it’s an AC and heater), allowing you to enjoy all-year comfort in your home no matter what season it is. The BTU rating of this differs according to the heating and cooling functions: it offers 18,000 BTU for cooling rooms up to 1000 square feet and 12,000 BTU for heating rooms up to 550 square feet.

These stats are pretty impressive for a heating/cooling system. Remember the heater is only efficient if it is used to supplement your primary heating system. It’s not intended to be the main source of heat for your home during the cold winter.

The LG LW1819HR also has a high energy efficiency ratio of 11.2 for cooling, meaning that it is a highly efficient system for keeping things cool. It also has an oscillating air vent, which circulates the air more efficiently. With its multiple cooling and heating speeds, you can ensure this model is energy efficient: you can turn down the speed when things are getting a bit too hold or cold.


  • Heats and cools


  • Requires a special 230 volt electrical outlet


5. hOmeLabs Window-Mounted Air Conditioner

The homeLabs 5000 BTU window-mounted air conditioner might have a small BTU rating, but it’s also a low energy air conditioner. The installation package includes side panel leaf covers and window seal foam, allowing you to ensure correct installation and energy efficiency from the moment you install.

The leaf covers will prevent debris from collecting in the unit. Debris can seriously hinder your unit’s performance, so this thoughtful detail ensures longevity and optimal running performance. The installation package also includes window seal foam. This ensures that there are no gaps in the installation, which could result in costly repairs.

With added features of seven speeds, two-way airflow, and adjustable fan settings, this small unit certainly packs a lot of punch. It can cool small rooms of up to 150 square feet in less than ten minutes, allowing you to conserve energy and money by switching it off when your room has reached the desired temperature. The multiple speeds and reusable, washable filter both will enable you to get the most out of your product by changing the speed to suit your needs and washing the filter regularly to ensure it doesn’t become clogged.

It also boasts dual cooling and fan settings so that you can switch back and forth between the two. If your room is cold enough, but you want to enjoy the cool air, you can use the fan which will save power and energy. Then, when the temperature becomes a little too warm for your taste, switch back to the cooling setting.


  • Impressive installation package


  • Not suitable for larger rooms


6. BLACK+DECKER BWAC12WT Window Air Conditioner

The Black & Decker BWAC12WT is an interesting window air conditioner model. It is certainly a contender for the best energy star air conditioner. It’s energy star rated and has a BTU rating of 12,000. The price of just under $300 is very reasonable for a window air conditioner capable of a 12,000 BTU output, and the estimated yearly running cost of $90 also makes it a competitive addition to this list. With an energy efficiency ratio of 12.1 and the official approval of the EPA, it’s clear that the Black & Decker BWAC12WT is highly efficient.

These specifications ensure that the unit is energy efficient, but any consumer must still factor in the BTU output into the equation. A 12,000 BTU unit is going to expend more power than a lower BTU one, so buying an over-sized unit can increase your utility bills and negatively impact the environment. Still, if your room is big enough to require a BTU of this size, you can rest assured it won’t drain energy.

It includes a thermostat with a wide range of temperature settings, allowing you to get the room to the exact temperature you find most comfortable. It also has a timer function, allowing you to turn your unit on or off depending on when you need the room to be at its coolest.

For example, you might want to set the thermostat to a higher temperature or off entirely if the room is already cool enough. The sleep function allows you to save even more energy by adjusting the temperature and fan speed while you sleep. With three cooling and fan speeds, you can customize your indoor environment to suit your specific needs.

There may be times when the temperature is cool enough, but you want the air to circulate around the room. This is the ideal time to take advantage of the fan setting, so you can enjoy the cool air without having to actually turn the compressor on.


  • Energy Star rated
  • Reasonably priced


  • Another heavy model


7. COSTWAY Window-Mounted Air Conditioner

The Costway 5,0000 BTU might not have the most impressive BTU rating, but it is still one of the smallest energy efficient window air conditioner.

First, it only requires a low level of power for start-up, helping you to avoid surges of energy consumption every time you turn it on. It is capable of cooling a room up to 120 square feet and dehumidifies 1.16 pints per hour at the same time.

It has three cooling speeds: low, medium, and high. This allows you to customize the cooling output depending on the weather: when it’s pretty cool outside, you can operate it at the low setting and switch it off when the environment is at a comfortable temperature. It also has two modes: cool and fan. The cool mode is for when you need to inject cold air into the room, and you can then adjust it to the fan setting to ensure even circulation once the temperature reaches the desired level.

With a ten level thermostat control, the Costway 5,000 offers a decent amount of options for energy conservation. It’s a solid choice for any consumer who wishes to purchase a relatively low-priced unit for a smaller room that doesn’t cost a lot to run.


  • Low power start-up
  • Competitive Price
  • Compact Design


  • Limited BTU capacity


Energy Efficient Window Air Conditioners Buying Guide

Now that we’ve reviewed some of the best energy efficient air conditioners currently available on the market let’s look at factors to consider when making a purchase.

The good news is that since October 26, 2015, all Energy Star Rated window air conditioners are required to meet the new Energy Star 4.0 rating. This new standard means that as long as you’re buying an air conditioner manufactured in 2016 or later, you’re guaranteed to save at least 10% more on energy compared to earlier air conditioners.

That said, though, you’ll still be choosing from dozens of models coming from different manufacturers. The following section should help you pick the right air conditioner.

How to Choose an Energy Efficient Window Air Conditioner

We’ll focus on three primary areas;

  • What to look for when buying a new energy-efficient air conditioner
  • How to choose an air conditioner size
  • How to read an air conditioner’s energy guide label

What to Look for When Buying a New Energy Efficient Air Conditioner

There are four principle considerations when buying a window air conditioner to help you save energy and keep your energy bills at a minimum;

Size of the AC

Many people tend to go with larger ACs assuming that bigger should equate to better performance. Sadly, this isn’t true for air conditioners.

While larger conditioners do a terrific job cooling indoor air, they aren’t very effective at removing humidity. As such, your home may be left clammy and damp.

Smaller ACs, on the other hand, may not generate enough power to meet the desired indoor temperatures. This often results in the AC unit trying too hard which can result in faster wear and tear.

For these reasons, it’s essential to get the sizing right. We’ll discuss how to find the right AC size for your home in a short while.

EER and SEER Ratings

An air conditioner’s efficiency is rated based on the unit’s Energy Efficiency Ratio (EER) and Seasonal EER (SEER).

EER is the ratio of an AC’s cooling capacity (in British Thermal Units (BTU)) per hour. SEER is the cooling capacity per hour during a typical cooling season. The EER or SEER rating of an AC is calculated by dividing the cooling output during a given period by the electrical energy input during that period.

EER rating is displayed on the outside of every AC unit. SEER ratings, however, may or may not be shown. If you can’t find your SEER rating, the Air Conditioning, Heating, and Refrigeration Institute (AHRI) has developed a broad directory to help consumers find the units’ scores. The higher the EER or SEER rating, the more energy efficient an AC unit is.

Energy Star Certification

Always buy an Energy Star Certified air conditioner. Why? Because, without costing any more than standard ACs, these units consume way less energy and thus save both money and the environment. One study even shows that you could save up to $1,000 yearly just by choosing Energy Star Certified appliances.

To determine whether an AC unit is Energy Star certified or not, check both the package and unit for a square, blue Energy Star Certified sticker.

You can opt for window air conditioners under $100 to save even more on the initial cost if you’re really tight on budget.

Additional Considerations

Aside from the factors mentioned above, keep the following in mind as well;

  • Energy-saving settings: While most modern window air conditioners are designed to save energy, those with energy-saving settings do the job even better. That’s because this category of ACs automatically turn off the compressor as well as the fan once your space has cooled off, thus conserving energy.
  • Programmable temperature settings: In this modern age, you want to find a unit with a digital display that allows you to set precise temperatures. Programmable air conditioners are designed precisely for this. Additionally, they will enable you to schedule your AC to turn OFF when you leave and turn back ON when you get back home.
  • Wi-Fi compatibility: Finally, a great modern window air conditioner should also be Wi-Fi compatible. A Wi-Fi enabled AC can be controlled using a smartphone, meaning you don’t have to leave the sofa. This greater control often leads to increased energy savings.

How to Choose an Air Conditioner Size

Now, let’s go into detail on AC sizes. What size should you choose for optimal performance and comfort? Let’s begin with a mistake a lot of people make;

It’s about cooling capacity, not the unit’s dimensions.

For most people, when they hear the air conditioner size mentioned, the first thing that comes to mind is the physical dimensions of the unit. Don’t make that mistake. In the AC world, size doesn’t mean how large, wide, or tall the unit is; it means cooling capacity measured in BTUs.

Begin with some quick math

Now, to determine how many BTUs you need to cool your home, some quick math is necessary. The most common method of determining the correct number of BTUs necessary cool a space is known as the Manual J Residential Load Calculation. Manual J is a complicated procedure that takes into account a range of factors, including;

  • The size of the rooms in your home
  • The materials used to build the home.
  • The quality of the home’s insulation
  • Number and locations of windows in the home

Instead of learning this method, however, many experts recommend simply dividing the square footage of your home by 600. If you choose this approach, do not include your garage or basement. Here are the best basement window AC units.

Aside from size, the age, orientation, and layout of the home may also determine the number of BTUs. For instance, a modern, energy efficient home may require less air conditioning compared to an old architectural home built in the 70s. The following adjustments are also recommended;

  • If the room is too sunny, increase the BTU value by 10%
  • If the room is heavily shaded, reduce the BTU capacity by 10%
  • If you intend to place the AC unit in the kitchen, increase the size by 4,000BTU
  • If more than two people will be occupying the space at any given time, increase the capacity by 600 BTU

Once you’ve obtained an approximate BTU number, proceed to compare it with what your HVAC professional recommended. Ideally, the figures should be within 6,000 BTUs of each other. Otherwise, speak to your window AC Brand technician.

Locating the AC size on your AC Unit

Armed with the approximate required AC size calculated above, you can now begin shopping. Most air conditioners have the size displayed prominently on the appliance. If not, check the model number. For example, the model number GCGD18 means the AC has a maximum capacity of 18,000 BTU.

Now, go on and pick the right size.

The following is a simple chart showing average cooling requirements for different space sizes. Just remember that these average values and should therefore only be used for guidance rather than as final figures.

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Sometimes AC sizes are given in tons. Converting BTU to tones is simple; 1 ton = 12,000 BTU. An 18,000 BTU AC, therefore, has a cooling capacity of 1.5 tons.

How to Read an Air Conditioner’s Energy Guide Label

To help consumers better understand the appliances they’re buying, the Energy Labeling Rule requires all AC units to be accompanied by a bright yellow Energy Guide Label (shown below).

Here’s what each section of the label means.

  1. Lists the type of air conditioner you’re buying, and it’s key features
  2. Contains the make, model, and size of the appliance
  3. Has the approximate projected yearly cost of running the AC
  4. Lists the average cost of running similar machines
  5. Where the EER rating appears
  6. Houses the Energy Star label

Ways to Maximize Your Energy-Efficient Air Conditioner

If you’ve followed the guide up to this point, rest assured of coming away with an incredible window air conditioner.

The next step is to install it and begin enjoying the perks of a modern, energy-efficient AC. As you do that, you should also be thinking of ways to get the most out of the unit without worrying about your energy bills.

The following are top tips to help you achieve this goal.


  • Close windows and doors

Your conditioned air can easily escape through the windows and doors. The only way to stop is by keeping all (or most of) your windows and doors closed most of the time.

  • Plug any air leaks in your home

Air leaks are one of the leading causes of cooling inefficiency. If you want to keep your conditioned air indoors, ensure that all spaces in the attic, under the doors, and around windows are sealed.

  • Maximize airflow around the condenser

Items such as plants and furniture tend to obstruct airflow. Ensure that such things are located at least 2 meters away from the condenser.

  • Change your filters regularly.

Aside from allowing polluted air to enter your rooms, dirty filters also block air flow thus reducing efficiency. Frequently changing your filters should solve this problem.

  • Don’t use registers for temperature control

Registers are good. But, they also interfere with indoor cooling needs. When you open and close your registers, cooling load changes. This can result in cooling inefficiency.

  • Invest in a zoning system

Most homeowners desire a situation where they can turn cooling ON in some rooms and OFF in other places at the same time. This can be achieved with a zoning system.

  • Set the AC to go off when you’re not home

Alternatively, set the thermostat to up a few degrees. Both settings will help you save a lot of energy. Also, shutting down the system for a few hours every day boosts the unit’s life.

  • Install and use ceiling fans

To help with cooling, set the fans to run in a counter-clockwise direction to pull cool air down where it’s most needed. This will also prevent your cool air from rising and escaping.

Tips for Maintaining Window Air Conditioners

Still, on extracting maximum value from your air conditioner, proper maintenance is critical in ensuring that the unit remains in top working condition for as long as possible.

The following maintenance tips should come in handy;

  1. Filter maintenance:

    There are two broad types of AC filters; those that can be replaced and those that can’t. Whichever model you’re using, maintenance is critical. Dirty, clogged filters typically force the AC to work harder to meet cooling needs. This can result in faster wear and tear. For this reason, if using reusable filters, wash them twice a month with unscented detergent. For non-reusable filters, replace them at least once every month.

  2. Evaporator and condenser coil maintenance:

    While regularly changing or washing your filters as necessary goes a long way in alleviating the buildup of dirt and dust in the evaporator and condenser coils, visually inspecting these parts is still essential. Once a year, either vacuum the coils using a brush attachment or remove the unit from its casing, set it outside, and thoroughly wash it. After washing, apply an all natural cleaner, rinse off the filter, and dry the coils before putting them back.

  3. Coil fins maintenance:

    The coil fins on both evaporator and condenser coils can sometimes bend thus compromising the efficiency of the AC. Make it your job to regularly inspect these fins and repair any bent ones. You’ll need a fin comb to straighten bent fins. When buying a comb for this purpose, ensure that the teeth count matches the fins-per-inch count on your coil.

  4. Preventive maintenance:

    Finally, all machines perform much better with preventive maintenance and air conditioners are not different. If you want your AC to last nine years or more, you need to schedule regular maintenance even when the unit isn’t broken. More importantly, the maintenance must be performed by a licensed HVAC professional. Most homeowners perform such maintenance in spring.

Wrap Up

The reviews above highlight the fact that the window air conditioner market is thriving, as different manufacturers compete to offer you the best, and most energy efficient window air conditioner. With models like these to choose from, it’s no surprise that window air conditioners are rising in popularity. Their energy saving and customizable features are certainly giving all round air conditioning systems a run for their money.

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Ronald Watford, the owner of Quality Home Air Care, is a qualified HVACR technician and manages the team of expert writers on this site. He believes that educating homeowners about HVAC systems is one of the most impactful aspects of his job.