Most Energy Efficient Window Air Conditioners in 2021

As one of the major reasons for global warming is due to air conditioners, you would want to find the most energy efficient window air conditioners in order to avoid the high costs of utility and electrical bills that the window ac will definitely generate.

As such, we have compiled a list of the most energy efficient window air conditioners in 2021.

Why Are Some Window Air Conditioners More Energy Efficient?

Some window air conditioners are more energy efficient than others due to the reason that they require less power and electricity to operate. As time goes on, the advance in technology related to window air conditioners has made it possible for modern window air conditioners to consume less power but still be able to produce more cool room air.

Features that the certain window air conditioner has to do this would be, for example, recycling their cooling water in order to ensure it lasts longer. Other techniques that help save energy include side panels that block off and trap cooler inside room air while still blocking the warmer air from outside.

As such, you will definitely be able to save a couple of bucks when utilising one of the suggested window air conditioners.

How different is one of the energy efficient window air conditioners from another?

There is no simple way to directly answer this question as in reality, the common energy efficient window air conditioner does not exhibit a lot of differences in properties from other air conditioners.

There is one basis of energy rating that you can refer to which means the higher the rating, the higher the efficiency of the energy efficient window air conditioner. A good example is that a 12 EER energy efficient window air conditioner will consume more energy than a window air conditioner with a 13 EER.

Overall, all energy efficient window air conditioners serve one purpose which is to extract out all hot air from your room and then produce cold air into the room at the same time without increasing cost, which will result in lesser pressure placed on your bills.

Factors to Consider When Selecting an Energy Efficient Window Air Conditioner

There would be some factors that you still have to consider when selecting your air conditioning.

Energy efficiency

Obviously, the first thing to look for on your window air conditioner will be the energy efficiency or energy star that is placed on the unit. This is because you would want to stay cool without incurring a high cost of deciding to implement a central air conditioning system.

You should keep an eye out for Energy Efficient ratio (EER Rating) or energy star rating that determine how efficient your window air conditioner is as it is a good comparison when measuring energy efficiency.


A window air conditioner that does not cool you off is useless so you would get yourself a window air unit that will be able to consistently provide and deliver cool air to you effectively on a basis that is reliable. This is so that the ac unit, once turned on – you can effectively forget about it and also be hot completely.

Ease of use

Your window air conditioner should have clear and easy to use instructions in order to work well for you. You do not want a window air ac unit that needs constant work and fiddling in order to work the way you want to set the room temperature correctly. As such you should select a window air conditioner that has simple setting systems.

Size increases result in efficiency decreases

Not all air efficient window air ac units come in the same sizes, instead, there are probably several sizes that you would be able to choose from. This is the same whether you select a central air unit or mini-split ACs.

However, there is one general rule that every window air conditioner follows and this is that the larger the ac unit is, the less of an energy efficiency rating it will get. Energy Star ratings take this into consideration as showcased below.

A 10.8 CEER 6,000 BTU air conditioner unit will not meet Energy Star requirements while a 10.8 CEER 24,000 BTU air conditioner will meet Energy Star REquirements.

You should not look out and depend on most online lists of energy-efficient window air conditioners as they mostly only show between 6,000 BTU and 8,000 BTU models. What happens if you require a larger window air conditioner?

No matter how efficient your air conditioner is, it is meaningless if your efficient window air conditioner is not able to cool the area it is supposed to cool. It is useless for a 6,000 BTU Air conditioner that is designed for up to 250 square feet used to cool an area that is 500+ square feet and it will not do the job.

As such, efficiency is meaningless if the air conditioner is not big enough to cool your room.

One large efficient window-mounted air unit vs several small window units

It would seem a little obvious that it is probably cheaper to just purchase one large window mounted unit vs two or three smaller window mounted units, but there is a hidden issue to this solution.
How effective the one large energy efficient window air conditioner will largely depend on the floor plan of your home.

Open Floor Plan

If your home has an open floor plan – which means when airflow is not restricted by any doors and walls, the choice of one large window unit air conditioner is easy.

This is because the large energy efficient window ac would probably have enough wattage power to push all cool and dehumidified air to every square foot of your open floor plan. You will still need to decide to strategically place the energy efficient window unit so that the air will go where it needs to

Closed Floor plan

Some older types of homes would have floor plans that are not as open with more individual rooms and as such, the best way would be to get several window ac as a room air conditioner. If this is the case, you should get ac units that are smaller for saving energy use.

This option is great especially if one of the rooms in your home is being used as a home office and your plan is to limit any noise from other parts of your home. Some people try to only use one larger window ac unit and utilise a few fans to push the air where they want but what just ends up happening is that it creates a lot of noise and uses up quite a lot of electricity.


Bedrooms of a home are a special challenge due to the closed-off nature of the rest of the house. As this is the case, it is recommended to get one small window ac for any bedrooms and you will be able to just turn off the larger ac window unit in the main part of your house in order to keep energy use to a minimum.

This means that you will always have the option to either just keep the bedroom or bedrooms cool at night with just one small window unit.

Window AC Units vs Central Air Conditioner Units

If there is talk about cooling large, main areas which include the bedroom and home office, then central air conditioning would be an option especially for homes in areas that are usually humid and warm.

However, for houses in cooler climates, there is always another alternative especially if days generally get warm but cool down during the evenings and night so a central ac unit is actually not required.

You could consider a whole house fan as they are able to exchange all the hot air indoor and cool outdoor air with time.

Is it worth it to pay more for higher efficiency air conditioning?

If you are living in an area with a hot climate, then you should probably get the most energy efficient window ac that you can. This is because of the following facts.

1) Your utility bill on electricity will increase by 20-30% depending on the models in the list is compared

2) You will spend about 15%-30% more for one of the energy efficient window ac compared to a window ac with low efficiency.

3) The hotter the climate your house is in, the more efficient you are able to recover the 15% to 30% extra that you paid for. It is more common for 7-12 years of payback in cooler climates while in warm and hot climates the payback usually occurs within 3-6 years.

Effects on the environment

As the climate is constantly changing, we should still strive to reduce the negative effects on Earth as much as we can, and as such, energy efficient air conditioners are more eco friendly than an air conditioning that has high energy use.

Currently, on the market, the window AC’s that are most environmentally friendly are those with high Energy Star energy efficiency rating and also one that possesses an R32 refrigerant as the R32 refrigerant is widely regarded as one of the most significant steps forward that is able to cut global warming potential by over 50%.

How to Select Your AC

The first step in selecting an AC model will be to compare the space and size correctly which can be broken down into a three-step process.

Step 1

Firstly, calculate the area by multiplying the floor’s length by its width in order to determine the floor area. If your floor area is more rectangular, then you will need to take the triangle’s base length and multiply that by its height and then divide it by half.

Step 2

You will need to multiply the number you get by 20 times which will give you the approximate BTU of the AC unit that you will need to purchase. It is okay if you want to multiply it by 22 or 23 as it is just a rule of thumb and not exact since some rooms can get especially hotter so a higher BTU number is fine if you can afford it.

Step 3

With step 1 and 2 in mind, you will then select the air conditioner with the highest possible EER rating and determine how much electricity it will use when converting warm air into cool dry air.

Most Energy Efficient Window Air Conditioners in 2021

1 ​Friedrich Chill Series CP10G10B Window Air Conditioner, 10,000 BTU, 115v, Energy Star

The Friedrich Chill Series CP10G10B 10,000 BTU window ac is a great choice when you are talking about cooling capacity and energy saver window ac units. THis is because it has a high- efficiency rating so you will know that the price you use to pay for the unit will be worth it.

This option is highly recommended if you already possess a central ac unit but do not really want to spend a lot more on a unit that you want to use just to cool your bedroom since the cooling of your whole house is already done.

This unit is also quiet, as during night time it will not make a lot of noise until the point it keeps you awake as both the fan and compressor on this unit are quiet and do not produce rattling noises.

The fully functional remote control that comes with a timer control would definitely be convenient to the point that it makes your life easier as you can set it to turn right on before you get home from work. It is easy to install and has a removable external chassis which makes it easy to take the unit itself outside for cleaning while the case is still sealed inside of the window and can be easy to install for even just one person.

The only drawback is that it could be quite cumbersome when you want to change the cooling filter.


  • Dry mode for humid days
  • Sturdy and well built
  • Reliable
  • Full function remote control available
  • Oscillating vent


  • The effort required to change filter
  • Low-quality customer service

2 LG LW8017ERSM Smart Window Air Conditioner (Wi-Fi), 8,000 BTU 115V, White

The LG LW8017ERSM Smart Window Air Conditioner has just a few drawbacks compared to the ​Friedrich Chill CP06G10B 8, 000 BTU Window Air Conditioner but only in small steps as this unit offers some impressive convenience features which include the remote control option to close the outside vent in order to block any unpleasant smells that may originate from outside your home.

This 6000 BTU unit also possesses some side panels that function as an energy saver by sealing in as much cool air as possible. The vent is located and faced upward on the unit so that if you install this unit in the bedroom, the cold air will not be blowing into your face but instead smoothly dissipate throughout the whole room. This effect is greatly enhanced with rooms that are 340 square feet and below.

There is a remote control that comes with this unit so that it can be adjusted from far away as well as a direct control panel on the unit itself to control fan speeds.

The best feature about this LG cooling unit is that it is energy-saving to the point that it still works during “brownout” periods which are when your local utility companies lower the power wattage provided due to higher outdoor temperatures as well as their associated risks. This cooling unit will be able to help save you money as well as be easier on the environment.

It has pretty good features that are convenient and will definitely help make your life easier but it is recommended to purchase your own insulation foam for this unit.


  • Quiet and easy to use
  • High cooling capacity
  • Efficient in cooling rooms quickly
  • Great for rooms with a lower number of square feet


  • Hard to read instructions
  • Ineffective insulation foam

3 MIDEA MAW05M1BWT Window air conditioner 5000 BTU with Mechanical Controls, 7 temperature, 2 cooling and fan settings, White

The MIDEA MAW05M1BWT Window air conditioner is a great energy-efficient window ac that cools smaller spaces quickly and is especially great if you are looking for an energy saver unit that can be easily removed and also stored away in a small space during the winter and then reinstalled again if the weather outside is getting warmer.

Our readers report that this unit is incredibly easy to install and uninstall with the whole process taking less than 10 minutes!

Due to its compact size, you will be able to just store it in a small space in either your storage rooms or garage when it is not being used during the cooler seasons. This model also comes with both 6,000 BTU and 8,000 BTU models for that higher cooling power purpose for larger rooms.

Due to the size, it is also small enough that you can mount it on a window without utilising an outside support bracket so there is less work required, and is suitable for windows 23”-36” wide and minimum 13” high and comes with all mounting accessories.

The MIDEA MAW05M1BWT window air conditioner comes with 7 temperature settings, 2 cooling/2 fan-only speeds and also a 2-way air direction to provide you with the perfect amount of cooling every time.

The 5,000 BTU unit would be perfect for cooling a room up to 150 square feet and is energy – efficient with a Combined Energy Efficiency Rate of 11.0 for energy savings and reducing the cost of your electricity bills.


  • Quiet
  • Lightweight
  • Easily installed
  • Cools small rooms quickly
  • Compact size for easy storage
  • Washable filter


  • Does not work as efficient in larger rooms

4 TOSOT 10,000 BTU Window AC with Remote Control, Energy Star Cools Rooms Up to 450 Sq Ft

The Tosot window AC is great as it would be similar to bringing an art gallery back to your home as the unit possesses a minimalistic and sleek look into your home window. It does however require a window opening with a 25-40” W x 22.8” D x 18”H.

It is light and also quiet with the highest noise rating of the unit at 69 dB. The unit also covers up to 350-450 sq feet. It is a great addition to your home as the AC comes with sleep mode, a dehumidifier for those rainy days and also a fan mode which would definitely help to bring more convenience and comfort into your home.

This TOSOT Window AC unit is high Energy Star rated so you will not have to worry about your impact on the environment as well as your wallet when you turn on the unit on those hot days to just cool off. Although the issue of climate change is not something everyone can agree one, we all do agree that a lower electric bill is better.

Most AC’s come with the thermostat located on the unit itself but for this Tosot unit, the thermostat is located on the remote. What this means is that your AC will cool your space based on the temperature around the remote instead of the ac unit.


  • Quiet
  • High Energy Star rated
  • Easy to install
  • Remote control
  • Great Aesthetics
  • 24-hour Sleep mode


  • Price

5 Frigidaire FFRS1022R1 10000 BTU 115-volt Slider/Casement Room Full-Function Remote Control Window AC, 10,000, White

The Frigidaire FFRS1022R1 window AC is a great addition to our list as the feature that stands out the most to us is that this unit is specially designed for being installed on sliding windows or casement windows. The product comes with an installation kit specifically designed for this purpose but it is important to note that it will not be suitable for any standard window installation.

You would definitely want this AC model if you are looking to cool a room up to 450 sq feet. This Frigidaire model also comes with dehumidification of up to 3.4 pints per hour when using a standard 115 V electrical outlet.

Other terrific features that come with the unit includes a 24 hour on/off timer and a fully functional control remote for adjusting the unit at range. It also possesses auto cool, energy saving mode, sleep mode, a 4-way air direction and an easy to use washable mesh filter with a check filter alert when cleaning is required.

The Frigidaire FFRS1022R1 possesses an Energy-efficient ratio of 10.4 so it is definitely energy saving in order to keep utility and electrical costs low.


  • Energy efficient
  • Designed for sliding windows
  • High cooling power
  • Multi speed electronic controls


  • High price point compared to other options on this list

Frequently Asked Questions (FAQ)

Q: What is the most Energy Efficient temperature for air cooling?

The most energy efficient temperature would be between 75 and 78 degrees Fahrenheit and this can save up to 50% of your costs so using your AC between these temperatures will definitely keep your room cool while simultaneously reducing energy consumption.

Q: What does EER stand for?

EER actually stands for Energy Efficient Ratio which is a metric that is mostly used when describing smaller AC units and the EER can help you compare the two different types of models in order to help determine which of the models will be the best in helping you save more energy.

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