Air conditioners are essential on those hot and humid summer days, but that relief can come at a price. An AC can quickly drive up a utility bill. The average window air conditioner uses 900 watts of energy per hour, while a central air conditioning unit can use upward of 3,000 watts per hour on hot days. At the average utility rate of 10 cents per kilowatt-hour, a central AC unit can add as much as $90 to your monthly utility bill.
Fortunately, there are energy-efficient models that can slash those utility expenses. These Energy Star–rated air conditioners use smart technology, inverters, and other cutting-edge technologies to decrease the amount of energy an air conditioner uses. Read on to learn more about what makes an air conditioner energy efficient, and don’t miss our list of the best energy-efficient air conditioners on the market.
- BEST OVERALL: Lennox SL28XCV Air Conditioner
- BEST BANG FOR THE BUCK: Keystone Energy Star 5,000 BTU Air Conditioner
- RUNNER-UP: Amana AVXC20 Air Conditioner
- BEST WINDOW AIR CONDITIONER: LG 18,000 BTU Smart Window Air Conditioner
- BEST MINI SPLIT: MRCOOL DIY Gen-3 Mini Split Air Conditioner
- BEST PORTABLE: Whynter ARC-14S 14,000 BTU Portable Air Conditioner
- BEST THROUGH-THE-WALL: Frigidaire 8,000 BTU Through the Wall Air Conditioner
- BEST INVERTER: Midea U Inverter Window Air Conditioner
Types of Energy-Efficient Air Conditioners
From central AC units to portable models, air conditioners come in various shapes and sizes to suit different needs.
Split Air Conditioners
A split air conditioner, often referred to as a central air conditioner, pairs a compressor and condenser placed outside the home with an indoor unit that consists of the evaporator, air handler, and filters. This type of system uses ductwork that runs throughout the house to cool all living areas in the home.
Packaged Air-Conditioning Systems
A packaged air-conditioning system consists of a compressor, coils, and air handler that are all located in a single metal cabinet. This design saves indoor space by housing all the AC’s components outside. Similar to a split air conditioner, a packaged air conditioner distributes the cold air it creates through a network of ducts.
Window Air-Conditioning Units
A window air-conditioning unit consists of a metal box that contains all the components of an air conditioner: compressor, coils, and air handler. The box is mounted between the sash and sill of a window and works by drawing air in from a room, cooling it, then recirculating the chilled air to cool a single room. Warm air and moisture that the window unit creates as a byproduct of the cooling process is expelled outside.
Portable Air Conditioners
Portable air conditioners consist of a stand-alone unit that houses a compressor, coils, and fan that sits on wheels. The air conditioner draws air in, cools it, then redistributes it back into the room. Since portable air conditioners do not sit in a window, they have hoses that must be attached to a window to vent the warm air and moisture it creates.
Ductless Mini-Split Air Conditioners
A ductless mini-split air conditioner has a compressor condenser outside of the home that connects to a small air handler inside one room of the home to heat that particular space.
Through-the-Wall Air Conditioners
Through-the-wall air conditioners are very similar to window air conditioners in their construction. Rather than mount to a window, through-the-wall air conditioners mount to an opening in an exterior wall. This type of AC is ideal for those who want to preserve the windows in a room.
Inverter Air Conditioners
Inverter air conditioners include some ductless, through-the-wall, window-mount, and split air conditioners. This type of unit includes an inverter that regulates the amount of electrical current an AC unit receives. Whereas a standard AC unit provides 100 percent of the air conditioner’s wattage whenever the compressor is running, an inverter regulates output in small increments, only giving the compressor the amount of energy it needs to cool the room. This design makes the AC unit’s compressor up to 40 percent more energy efficient than a standard air conditioner.
What to Consider When Choosing the Best Energy-Efficient Air Conditioner
Air conditioners are assigned energy-efficiency ratings that are helpful when shopping for the best home air conditioner—but only the shopper knows what they mean. Ahead, learn about the three types of energy-efficiency ratings and other important factors to consider when choosing the best AC unit, including size, BTUs, and smart capability.
Size and Square Footage
Finding the right-size AC unit to suit the space is critical. A unit that’s too small will run constantly to try to keep the temperature cool. An air conditioner that’s too large will cool the space too quickly, turning on and off in short bursts that put undue wear on the compressor. With this in mind, it’s crucial to make sure the cooling capacity of the air conditioner suits the square footage of the space it’s cooling by looking at its BTU rating.
BTU, or British Thermal Unit, is a measure of how much heat an air-conditioning unit removes from a home in 1 hour. An AC unit’s BTU measurement is crucial for determining what size air conditioner is needed for a home or room. Air conditioners need about 20 BTUs for each square foot of living space. This means an 8,000 BTU window air conditioner is suitable for a 400-square-foot room; a 54,000 BTU central AC unit can cool up to 2,700 square feet.
Temperature and Energy-Efficiency Settings
Air-conditioning units vary the sophistication of their temperature controls. Split air conditioners and most mini-split AC units connect to thermostats that allow the user to dial in specific temperature settings. While some window and through-the-wall models also allow for specific temperature settings, some lower-end units have less-specific “high” and “low” settings.
Some window air conditioners also have energy-saver modes that reduce the amount of power the AC unit uses. When in this mode, the air conditioner alternates between cooling mode and fan-only mode, reducing the amount of electricity the air conditioner uses but also reducing its cooling power.
High Energy-Efficiency Ratings
Several ratings are used to delineate how energy efficient an air conditioner is. Energy Efficiency Ratio (EER) measures how efficiently an air conditioner operates and is determined by dividing the air conditioner’s BTU rating by its wattage. The higher an air conditioner’s EER, the more efficient it is.
CEER (Combined Energy Efficiency Ratio) is the standard by which the Department of Energy rates the energy efficiency of window-mount air conditioners. The rating reflects a window AC unit’s energy use when it’s running and when it’s in standby mode.
SEER is the rating most commonly used to measure the efficiency of central air conditioners, also known as split air conditioners. SEER ratings measure how well an AC unit will cool the home for an entire season. The higher an air conditioner’s SEER rating, the more efficient it is. The average central AC unit has a SEER rating of around 12; energy-efficient models might have a SEER rating of 14 or higher.
The best AC units have an Energy Star rating, which means the air conditioner meets federal guidelines for energy efficiency. Most Energy Star–rated window air conditioners must have an EER of around 12, which is significantly higher than the 8.5 EER rating the average window AC unit has. A central air conditioner must have a SEER rating of at least 14.5 to qualify for an Energy Star rating.
Many air-conditioning units are able to connect to a home’s Wi-Fi network, enabling smart features. Users can control a WiFi-enabled air conditioner via an app on a smartphone, scheduling on and off times as well as temperature changes. While these features add to the up-front cost of an air conditioner, they also improve its energy efficiency by allowing the user to turn the AC off or bump the thermostat up a few degrees when the room or home is not in use.
Our Top Picks
The models below are some of the best air conditioners on the market for energy efficiency. They are Energy Star rated and loaded with features that help the owner regulate their use for maximum energy savings.
The SL28XCV takes over for Lennox’s XC25, which had been widely regarded as being the most energy-efficient central AC unit money could buy with its 26 SEER rating. The SL28XCV takes it up a notch by achieving sky-high efficiency ratings of 28 SEER and 17.6 EER, thanks to a variable-speed inverter compressor. Those ratings put it well above the government’s minimum efficiency rating of 14.5 SEER for Energy Star–rated air conditioners.
Additionally, a user can cut costs even further by pairing the SL28XCV with Lennox’s iComfort S30 smart thermostat to program on/off times and set schedules. The inverter compressor also has the added benefit of being quieter than most AC units at just 56 decibels. And while the high efficiency comes with a high price tag, the Lennox can make up for those costs fairly quickly in energy savings, as the SL28XCV is 63 percent more efficient than a 10 SEER unit. The SL28XCV comes in four sizes ranging from 22,400 to 57,000 BTUs.
- Energy efficiency: 28 SEER
- Type: Split with inverter compressor
- BTUs: 22,400–57,000
- High SEER rating
- Quiet operation thanks to inverter compressor
- Works with Lennox’s iComfort S30 smart thermostat
- One of the most expensive AC units on the market
Get the Lennox SL28XCV through a licensed HVAC contractor.
The operating modes and energy-efficiency rating of this small window air conditioner make it an excellent option for anyone needing an affordable way to cool a single room. With its 12.1 EER rating, this Keystone model is among the most efficient window air conditioners on the market. In addition to its Energy Star rating, it features operating modes that allow it to cut even more energy costs, including an energy-saver mode and an on/off timer the user can program to turn it off when the room is not in use.
At 5,000 BTUs, the Keystone is capable of cooling spaces up to 150 square feet, making it one of the best small air conditioner options on the market. It also comes with a remote control that doubles as the unit’s thermostat, making it easier to operate while also ensuring an even temperature throughout the space.
- Energy efficiency: 12.1 EER
- Type: Window air conditioner
- BTUs: 5,000
- Excellent energy-efficiency rating
- Remote control with integrated thermostat for even cooling
- Programmable on/off timer
- Only suitable for smaller rooms
Get the Keystone Energy Star 5,000 BTU Air Conditioner at Walmart, The Home Depot, or on Amazon.
Amana’s Energy Star–rated AVXC20 ranks as one of the most efficient central air conditioners on the market, thanks to its 24.5 SEER rating. Like other high-efficiency air conditioners, Amana achieves this rating with an inverter varied-speed compressor that keeps energy use low. The AVXC20 is also equipped with Amana’s ComfortNet thermostat, which offers more potential for cost savings by giving the user the ability to control the system remotely and set schedules to increase the temperature when no one’s home.
ComfortNet will also monitor the system and let the user know when it requires maintenance. In addition to being energy efficient, the AVXC20 is quiet. Its design includes a sound-reduction cover consisting of high-density foam.
- Energy efficiency: 24.5 SEER
- Type: Split air conditioner
- BTUs: 24,200–53,000
- High energy-efficiency rating of 24.5 SEER
- Comes with ComfortNet smart thermostat system
- Quiet operation design
Get the Amana AVXC20 through a licensed HVAC contractor.
With its inverter technology, this window air conditioner from LG is both efficient and quiet. This Energy Star–rated air conditioner puts out 18,000 BTUs on just 1,250 watts, giving it an EER of 14.4 and making it the best window AC unit on the market when it comes to efficiency. With its ability to cool spaces up to 1,000 square feet, it’s suitable for large family rooms and open floor plans.
This air conditioner also has smart controls, so the user can turn the unit off or on remotely and set schedules via a smartphone, which can save money by setting it to a higher temperature when the room is not occupied. The LG is one of the quieter window air conditioners on the market, too, putting out just 44 decibels while in sleep mode.
- Energy efficiency: 14.4 EER
- Type: Window air conditioner
- BTUs: 18,000
- High efficiency rating
- Wi-Fi connectivity allows the user to control it remotely with a smartphone.
- Capable of cooling large rooms
- Quiet operation
Get the LG 18,000 BTU Smart Window Air Conditioner at The Home Depot or Lowe’s.
While this Energy Star–rated air conditioner’s 20 SEER efficiency rating is impressive, what really sets this 18,000 BTU AC unit from MrCool apart from other energy-efficient mini-splits is its smart connectivity. It can connect to Wi-Fi, allowing the user to turn the air conditioner off or on, set schedules, and adjust the temperature—all via a smartphone. It’s also compatible with Google Assistant and Amazon Alexa, and there’s a wall-mounted thermostat and remote control.
The device’s Follow Me function allows it to sense temperatures through the remote for more even cooling. This unit is also ideal for those who don’t care to pay installation charges: It’s DIY-ready with lines that are pre-charged with freon and fitted with quick connectors that make it easy to install.
- Energy efficiency: 20 EER
- Type: Mini split
- BTUs: 18,000
- High SEER rating
- Wi-Fi connectivity allows for smartphone control
- Follow Me function promotes even cooling
- Design for DIY installation
Get the MRCOOL DIY Gen-3 Mini Split Air Conditioner at The Home Depot.
One won’t find any Energy Star–rated portable air conditioners—the federal government doesn’t include them in the program—but if they did, Whynter’s ARC-14S would certainly deserve the rating. With an 11.2 EER rating, it’s the best room air conditioner on the market when it comes to energy efficiency. Its rating is due in large part due to its use of auto-drain technology, a process that recycles moisture collected during the cooling process to create more cool air, and the use of two exhaust hoses, a design that improves its ability to create cool air.
Those technologies give the ARC-14S an impressive 14,000 BTUs, enough to cool up to 500 square feet. In addition to being powerful and efficient, the ARC-14 also isn’t the eyesore that some portable AC units are, thanks to its sleek black design and digital controls. Despite weighing 80 pounds, the ARC-14S remains movable as a result of four ample casters that allow it to be rolled from room to room.
- Energy efficiency: 11.2 EER
- Type: Portable
- BTUs: 14,000
- Can cool larger spaces
- Sleek design and digital controls
- Auto-drain technology creates more efficient cooling
- One of the most expensive portable air conditioners
Get the Whynter ARC-14S 14,000 BTU Portable Air Conditioner on Amazon, at Wayfair, or at The Home Depot.
With its Energy Star rating, this 8,000 BTU air conditioner from Frigidaire is a great option for those looking for a through-the-wall option. It comes with a remote control that allows the user to set specific thermostat temperatures or engage one of its many modes. It also comes with an energy-saver mode and a timer that allows the user to program the unit to automatically turn off or on.
A 350-cubic-feet-per-minute fan provides ample circulation for this AC unit, which can cool larger rooms. The thermostat located in the remote control allows for more even cooling throughout the room.
- Energy efficiency: 11 EER
- Type: Through-the-wall
- BTUs: 8,000
- Includes remote control with thermostat
- Multiple modes for energy savings
- Quick-cool function rapidly chills a room
- More expensive than other 8,000 BTU through-the-wall models
Get the Frigidaire 8,000 BTU Through the Wall Air Conditioner on Amazon.
This 8,000 BTU window air conditioner uses inverter technology, which varies the flow of energy to the unit based on demand, to achieve an impressive 13.3 energy-efficiency rating. That translates to 35 percent more energy savings over standard window air conditioners. Inverter technology also makes the unit much quieter, with operating noise levels as low as 42 decibels.
This unit’s U-shaped design allows a window to close significantly farther than would be possible with traditional window AC units, helping to limit air loss. This novel design has the added benefit of allowing the window to be opened without uninstalling the air conditioner. And, since it’s Wi-Fi equipped, the user can control the unit and set on/off schedules remotely via an app.
- Energy efficiency: 13.3 EER
- Type: Window
- BTUs: 8,000
- High 13.3 efficiency rating
- Quiet operation
- Wi-Fi equipped
- Mounting style allows the window to open and close.
- More expensive than other 8,000 BTU models
Get the Midea U Inverter Air Conditioner on Amazon, at The Home Depot, or at Overstock.com.
With a SEER rating of 28 and smart features that make it easy to optimize its operation, the Lennox SL28XCV is one of the best energy-efficient central air conditioners available. For those looking to cool a single room efficiently, the Keystone Energy Star is a worthy choice.
How We Chose the Best Energy-Efficient Air Conditioners
We used a variety of criteria to review more than two dozen air conditioners of all types. Given that our goal was to include the best energy-efficient models, we limited our search to those with Energy Star ratings. Of those Energy Star–rated models, we leaned toward the ones with the highest efficiency scores.
We also favored those with features such as Wi-Fi connectivity and timers that allow the user to further control air-conditioning costs by ensuring the air conditioner isn’t running at full capacity when the room is unoccupied. While cost wasn’t a primary factor, we did favor energy-efficient air conditioners that offer the best bang for the buck.
Understanding how to maintain and operate an air conditioner to get the most out of it is key to keeping that utility bill in check during the summer months. Ahead, learn about the most efficient way to run an air conditioner and learn how upgrading your aging AC unit to a newer model can save you money.
Q. Do new air conditioners use less electricity?
A new air conditioner generally uses less electricity because it is more technologically advanced than older models. Air-conditioner compressors also cool less efficiently as they get older, forcing them to work harder and use more energy to cool the room.
Q. How can I reduce the power consumption of my air conditioner?
There are several ways to reduce the power consumption of an air conditioner. The most obvious is turning up the thermostat to a higher temperature. Clean the air conditioner and replace the filter regularly to ensure the air conditioner is in peak condition. If possible, switch to a smart thermostat that allows you to schedule on/off times for the air conditioner, so it isn’t running when it doesn’t have to.
Q. Is it cheaper to leave the air conditioner on all day?
It is cheaper to leave the air conditioner on all day during hot temperatures. Turning off the air conditioner during hot and humid weather can quickly cause heat and humidity to build up in the home. This places a strain on the air conditioner to cool the home when you turn it back on. A better option is to adjust the air conditioner by a few degrees when you’re not home.
Q. Is it cheaper to run AC or a fan?
Fans are much cheaper to operate than air conditioners because they do not use a compressor. It’s a good idea to use fans in combination with air conditioners to make the air feel cooler, allowing you to increase the thermostat a few degrees.
Q. How efficient is a 20-year-old AC?
A 20-year old air conditioner is much less efficient than today’s models. An older air conditioner may use 6 kilowatt-hours of electricity to cool an average house, while a modern system can use less than 2 kilowatt-hours to cool the same space.
Q. Which AC is more energy efficient: window or mini-split?
A mini-split air conditioner is much more efficient than a window unit. The average mini-split consumes 40 percent less energy than a window air conditioner to cool the same space.
Q. Is it cheaper to run a window air conditioner or central air?
It depends on what you’re trying to cool. If your goal is to cool a single room, then a window air conditioner is the best option. If you need to cool an entire home, it’s more economical to use a central air conditioner than placing a window unit in every room of the home.