Air conditioners may be considered a luxury in some places, but in others they’re pretty much essential to keep your cool as the weather and the climate warm. Window air conditioners, portable air conditioners, and central air conditioning systems are more affordable than ever and, thankfully, have vastly improved in energy efficiency. But, while A/C isn’t the energy hog it used to be, there’s still lots to consider when looking for an eco-friendly air conditioner.

Energy efficient air conditioners

To get an Energy Star rating, air conditioners must be 10 percent more efficient than similar models. In addition to looking for the Energy Star rating, you may want to account for the likelihood of brownouts (power outages) where you live; some air conditioners work even under brownout conditions.

Consumer Reports test air conditioners in a special climate-controlled chamber by turning up the heat to 90 degrees Fahrenheit and seeing how quickly a unit can drop the temperature by 15 degrees. They also note how well the unit holds to the set temperature, and make sure to adjust the test chamber to properly assess small, large, and medium window A/Cs.

Many folks have harangued Consumer Reports for not testing air conditioners over 12,500 Btus, noting that these units are inadequate to cool a stonkingly hot apartment in many places. While this may be true in some cases, there’s not necessarily an advantage to a bigger A/C and there could be several disadvantages, including the cost of energy.

If you have any control over the enclosure of your building, the best way to ensure energy efficiency in an A/C is to make your home leak-proof. This means adding insulation, caulking, cladding, installing thermal windows, draught excluders, etc. After all, if your home is leaky and letting in hot air, your A/C is going to be working way harder than it needs to.

Fun Fact: Energy Star estimate that if all room air conditioners sold in the U.S. were Energy Star certified, this would prevent more than 6 billion pounds of greenhouse gas emissions annually – the equivalent of the emissions from over 570,000 vehicles (R).

Go big or go… small?

It may be tempting to choose the biggest air conditioner you can afford or accommodate when buying a new A/C. This isn’t always the best option, though, as a unit that is too big for the room will cool down the air too fast, leaving moisture in the air. The result? A cold, clammy space that feels rather unpleasant.

An A/C that is too small, however, will struggle to effectively cool a room and is likely to be less energy efficient overall.

So, how do you figure out what size unit is best for your space? First, you’ll need to know the square footage (approximately) of the room or rooms you want to cool. To do this, multiply the room’s width by its length. If you’re trying to cool a room that adjoins another room without a solid door, you’ll have to add together the square footage of both rooms. Other things to consider include:

  • The room’s sun exposure or degree of shade during the day (plus or minus ten percent respectively)
  • The number of people using the room – for more than two people, add 600 Btu for each extra person
  • Add 4,000 Btu if the unit is intended for use in a kitchen
  • Consider the height of your ceilings – low ceilings mean less air volume overall and require less cooling than higher ceilinged rooms
  • The size and number of any windows and doors that may affect air flow and sun exposure
  • Window insulation – non-thermal windows will mean you need a higher cooling capacity during the day (but heat will escape faster at night)
  • Wall, floor, and ceiling insulation
  • Other sources of thermal mass (see above)
  • Your location – if you live in a high-rise surrounded by other high-rises, you’ll need to account for the heat island effect (especially with everyone else pumping hot air from their own windows!)

Unfortunately, if the last condition applies to you, as it does to many in built-up cities and downtown cores, even the largest of the window and portable air conditioners might not be up to the task of cooling your apartment by itself. In such cases, you may need two separate units beavering away at their highest settings. You can help reduce your use of A/C by keeping shades drawn during the day and installing a ceiling fan to keep cool air circulating.

Energy Star offer the following handy guide to work out the right Btu for a room air conditioner.

Area To Be Cooled (square feet)Capacity Needed (BTUs per hour)
100 up to 1505,000
150 up to 2506,000
250 up to 3007,000
300 up to 3508,000
350 up to 4009,000
400 up to 45010,000
450 up to 55012,000
550 up to 70014,000
700 up to 1,00018,000
1,000 up to 1,20021,000
1,200 up to 1,40023,000
1,400 up to 1,50024,000
1,500 up to 2,00030,000
2,000 up to 2,50034,000

Remember, the square footage above is for a single room, not the whole square footage of your home. Taking some time to measure your space could save you a lot of hassle and expense and is well worth doing some quick math.

Don’t forget noise pollution

When we think about an eco-friendly home, we sometimes forget to consider noise pollution. If an otherwise eco-friendly appliance runs loud, this in itself can make a living situation unpleasant. This is definitely something to consider if you value a quiet living space and find intermittent or loud noise disturbing while you sleep.

Thankfully, Consumer Reports takes noise output into account in their testing process. They measure how loud each unit is on its lowest and highest settings. Any unit rated Fair for noise is liable to disturb light sleepers even on a low setting and are a real noise nuisance on their highest setting. If noise is a consideration or you’ll need your A/C working overtime where you live, look for those with an Excellent or Very Good rating for noise from Consumer Reports. These units are very quiet and only really produce a low sound from the fan.

Central Air Conditioners

Central air conditioning is the quietest method of air conditioning and is built-in for many single-family homes these days. Simple to use, easy to control, and largely out of sight, central air has some serious advantages for many homes.

Central air does have some drawbacks, however. It can be a real pain to set up, is expensive to install, and is liable to be beleaguered by pressure imbalances and duct issues, even if you have the most wonderful contractor in the world. There’s also the fact that you can’t typically control the temperature in different zones, so the system will be working continually to keep your bedroom the same temperature as your kitchen, which doesn’t make a lot of sense in terms of energy efficiency.

Speaking of energy efficiency, central air conditioners are subject to different testing criteria than window and portable air conditioners in order to qualify for Energy Star certification. Arguably, the testing requirements give a skewed view of the energy efficiency of central air compared to window air conditioners. That’s because central air is tested for its Energy Efficiency Rating (EER) and for Seasonal Energy Efficiency Rating (SEER). Window air conditioners are just tested for EER.

Why does this matter? Well, because it may well be that manufacturers go all out to perform highly on SEER only to compromise actual performance in a home set-up (R).

Central air is also rarely an option for apartments, but it does have the advantages of helping to manage humidity, which most window air conditioners don’t do. For hot and humid southern states, this can be the clincher when deciding between central air and portable or window units.

One other thing to note is that because central air is so quiet and unobtrusive, you’re more likely to forget to turn it off when you leave the house. All that supposed energy efficiency means nothing if you’re running central air all day and night, cooling every room in your house whether they’re occupied or not. The good thing about the noise of a window air conditioner is that it reminds you to turn it off every once in a while!

Window Air Conditioners

Window air conditioners are an excellent option for most homes. They are relatively inexpensive, easy to install and maintain, and allow you to do zone cooling, unlike central air conditioning systems with all their ducts, pressure imbalances, and need to maintain the whole house at the same temperature.

In general, window air conditioners have a cooling capacity of around 5,000 to 12,500 British thermal units (Btu). As a rough guide, the cost of the unit correlates with the amount of square footage it can cool effectively: a $100 unit can cool around 100 square feet; a $600 unit can cool around 600 square feet, and so on.

Smaller units range from 5,000 to 6,500 Btu and are suitable for cooling around 100 to 300 square feet of space. Most such units cost between $150 and $250.

Medium-sized window A/Cs have a cooling capacity of 7,000 to 8,200 Btus and can cool around 250 to 400 square feet of space, making them suitable for many small bachelor or 1 bedroom apartments, if you only intend to cool the main living space or bedroom. These units cost between $200 and $400.

Larger window air conditioners have a cooling capacity of 9,800 to 12,500 Btus and can cool between 350 and 650 square feet, meaning they’re a good option for a single room in a larger house or apartment, or for a whole open plan bachelor or one bedroom apartment (depending on whether this is a loft apartment, has floor to ceiling windows and lots of sun exposure, etc.).

Larger units are large, bulky, and awkward, not to mention hard to install without professional help. They may also be banned by many condominium councils, so check the by-laws before you buy! These units range from around $350 to $600.

Speaking of by-laws, some condominiums don’t allow exterior facing window A/Cs at all. If this is the case, or if you’re looking for a single unit that can be moved from room to room as needed, a portable air conditioner is the way to go. Portable air conditioners are also a good idea if your window configuration won’t accommodate a window air conditioner.

How to install a window A/C

Most window air conditioners are designed to fit double-hung windows, i.e. windows that open vertically. A through-the-wall A/C unit may be the better option if you have casement windows, i.e. windows that slide left or right to open. Some casement window A/C units are available, however, and you could always rig up a bespoke air-tight system or switch out your windows.

Newer window air conditioners often have better insulating materials than older models as well as clearer instructions that help you position the unit with a good seal to minimize leaks.

To help ensure your window A/C runs efficiently, follow these top tips:

  • Make sure your unit is level in the window, so that it drains properly.
  • Position your A/C away from heat sources – these include lamps, televisions, and baseboard heaters
  • Make sure you can get to the unit’s filter, so you can clean it regularly
  • Clean the unit’s filter regularly!

Use the smart features on your air conditioner to control and adjust the unit. This way, you can avoid having the unit on all day and instead set it going an hour or so before you get home. Some let you do this on a timer, and some hook up to an app. so you can do it remotely.

Portable air conditioners

Portable air conditioners have a cooling capacity of between 9,000 and 15,500 Btu but tend to be less effective at cooling than many manufacturers claim, according to Consumer Reports. For similarly sized units, portable air conditioners are generally noisier, more expensive and use more energy than window units.

Portable air conditioners typically cost between $300 and $700 and can weigh around 50 to 80 pounds. Most, fortunately, have wheels, making them easy enough to roll around. If you have to move an A/C from one floor of your house to another, however, you’ll want to be sure you can comfortably and safely lift the unit before buying.

Should I put an air conditioner in my bedroom or living room or both?

Only you can decide if it makes sense to have a single portable air conditioner you move from room to room as needed or have an A/C unit in one or more rooms of your apartment or house.

As a general rule, you will get most benefit from an A/C in the bedroom as it’s important to have a cooler space to sleep at night. Your living room or other room of your home where you spend most time is the next-most important area to consider an A/C unit.

The least helpful place to put an A/C is in a kitchen that is closed off from the rest of the apartment or house. If you are cooking regularly, you may be fighting a losing battle to keep temperatures down, and it’s likely you’ll also have windows open or a hood fan on to help dissipate cooking odors, which make A/C much less effective. You may even want to consider a mostly raw food diet in summer, especially if it’s in line with your nutrigenomic profile!

Air conditioner features to look out for

A quality air conditioner will have easy to use controls that give you a good degree of flexibility in how you use the unit. This means things like a digital temperature display (avoid those with ‘warmer’ or ‘cooler’ settings only), built-in timer, remote control capacity, and buttons that are clearly labelled and easy to use even when fumbling in the dark.

Some units let you change the direction of airflow, which is especially helpful if you have an oddly shaped room or need to install the unit in a strangely situated window. Some units are better at directing airflow one way only, so be sure to look for one that meets your particular needs.

Energy-saving units typically have a feature where the fan stops when the compressor is off. Timers also help save energy by enabling you to start the unit just before getting home and turn it off when you’re out.

If you live in a more humid climate, look for an A/C with a dehumidifying mode. This is particularly helpful on spring and fall days. And, if you live in a temperate climate and may just want to use your A/C for ventilation and fresh-air intake without cooling, look for a model with this capacity (sometimes known as an ‘exhaust setting’).

One other thing you’ll want to look for is whether the unit has a variable speed compressor.

Single speed vs. Variable speed compressors

Most air conditioners have a single stage compressor, especially if they are central air conditioners. These are standard in many homes in the U.S., having been used for decades. So, why all the fuss about variable speed compressors and why should you look for one in your new A/C?

First, a single stage compressor turns on and runs at 100% capacity whenever indoor temperatures exceed the temperature you have set on your thermostat. It blasts cold air into your home and then turns off again once it reaches the required temperature. Sounds good, right? Not really.

Because single stage compressors turn on and off throughout the day, they actually use way more power than an A/C that runs almost continuously at a lower capacity. That’s because most of the energy used by an A/C is used to start the unit running, not to keep it running.

Second, a single stage compressor drops the temperature quickly, which doesn’t give the unit a lot of time to also strip moisture from the air. The result is that the room can feel cold and clammy instead of refreshingly cool.

In contrast, a variable speed compressor operates continually at below 100% capacity. Often, a variable speed compressor functions at just 25% or 30% of capacity and may well hum along all day on the hottest summer days. This cuts down on the stop-start action that uses up most of the energy in a single stage compressor. It also has the advantage of helping to dehumidify, so you actually feel cooler even at a higher temperature. That means you can set your thermostat a few degrees higher and still feel comfortable.

A variable speed compressor provides a steady stream of cold air to help achieve and maintain the temperature you want in your room or home. A single stage compressor blasts out short bursts of cold air in an on-off cycle, which is both noisy and energy-intensive (this is called ‘short-cycling’ and is bad news for your pocket book).

It’s worth mentioning that there is a middle ground between the two: the two stage or dual stage compressor. These types of compressor units have a high and a low level, so you can really blast the cold air to quickly cool down a room, or have the unit run at a lower capacity to maintain a comfortable temperature. These units cycle on and off less frequently than a single stage compressor, but you have to toggle the high and low levels manually and there are only two speeds.

So, variable speed compressors are definitely your best bet if you live somewhere humid and hot. If you’re used to a single speed compressor and switch to a variable speed compressor, try setting your thermostat a few points higher than you’re used to; you’ll very likely find you’re even more comfortable than with your old unit set super low.

Variable speed compressors are more efficient and effectively dehumidify the air, which also offers another advantage: air purification. That’s right, your shiny new A/C with variable compressor can help eliminate the growth of mold by reducing humidity in your home. And, because they run for longer, they filter the air for longer, meaning that indoor air has fewer contaminants. They may even help reduce the activity and presence of insects, dust mites, and other critters while being quieter than single or two stage compressors.

One downside of variable speed compressors is the cost. This will likely come down over time, but for now these units are quite a bit more expensive upfront compared to single stage compressors. Their running costs are lower, however, and you may find that you don’t need a separate air purifier, saving you money overall.

If your single stage compressor A/C doesn’t yet need replacing, but you are concerned about humidity in your home, your best bet is to go for a whole home dehumidifying system instead. And, if you have a single speed compressor you need to replace, but you love that blast of cold air and don’t live in an area with an especially humid climate (no more than around 55 relative humidity), choose a model with a better energy efficiency rating than your od model.

Now we’ve gotten all that out of the way, let’s look at some of the most energy-efficient, eco-friendly air conditioners available.

The best air conditioner brands

Hands down, LG get top marks for energy efficiency for room/window air conditioners overall. No other brand comes close to LG for Energy Efficiency Ratings, with several models rated at 14.7 and a few more rated above 14. The next best brands carry much lower ratings and include:

  • GE
  • Frigidaire
  • Danby
  • Arctic King
  • Emerson
  • Midea
  • Sea Breeze
  • Thermal Zone.

LG is a well-know, reputable, national brand available at a wide variety of independent and regional appliance retailers. Window units range in price from $150 to $500, and in Btu from 6,000 to 24,500. They’re generally your best option for energy efficiency for both single stage and variable speed compressors for every range of Btu, with the exception of 10,000-13,999 Btu.

Here are the best brands for the most energy efficient air-conditioners broken down according to cooling capacity:

  • 6,000-7,999 Btu – LG
  • 8,000-9,999 Btu – LG
  • 10,000-11,999 Btu – Gree and GE
  • 12,000-13,999 Btu – Soleusair, Cool Living, and Toscana
  • 14,000-19,999 Btu – LG
  • 20,000 Btu and above – LG.

Let’s look at these in more detail, with recommendations for the top pick in each category. I’ve listed the CEER for each unit, which is a Combined Energy Efficiency Rating based on the power used while the unit is running and while it is in standby mode.

A/C units with 6,000-7,999 Btu

The LG – LW6018ER is the winner in this category, followed by another LG model, Kenmore and Soleus Air.

Air conditioner brand/modelBtuCEER* Variable Speed CompressorAnnual Energy Use (kWh/yr)
LG – LW6019ER6,00012.4362.9
Soleus Air – WM1-06E-026,00012.1384.3
Kenmore Elite 770606,00012.1371.9

*CEER is the Combined Energy Efficiency Rating.

Both the LG-LW6018ER and the LG-LW6019ER are recommended by Consumer Reports with matching scores of 78. They offer the highest Energy Star ratings in this category and use 362.9 kWh/yr to provide 6,000 Btu. The 6019ER model costs $270 and tends to blow air to the right of the unit, while the 6018ER model costs $200 and has more even air flow.

The key difference between the two models is that the 6018ER model has been discontinued, seemingly replaced by the more expensive 6019ER which is not yet widely available for sale. I suspect that sales listings for the 6018ER at Amazon and other online retailers will soon be updated to the 6019ER, so take note of some of the measurement and weight differences between the models before buying.

Both the 6018ER and 6019ER models have an auto restart mode, use a standard 115-volt/15-amp electrical outlet, can cool a room up to 260-sq. ft. and dehumidify up to 1.8 pints per hour. The 6018ER weighs 62 pounds, measures 19.4 x 19.6 x 12.4 in. and has a slightly larger maximum window width of 38 in. compared to the 6019ER’s of 37 in. The 6019ER model measures 19 9/16″ x 12 3/8″ x 19 3/8″ and weighs 56 pounds. Other than that, they appear to have the same functionality and offer the same decent CEER. Given their similarities, it’s likely the 6019ER will share the same great reviews as the 6018er.

If you don’t manage to snap up a bargain $200 LG – LW6018ER before they run out, you might want to consider the Kenmore Elite 77060. This A/C has a Consumer Reports score of 73, a little lower than the LGs, and is a 6,000 Btu unit ideal for cooling a room up to 250 sq. ft. It costs around $220 and dehumidifies up to 1.3 pints of moisture per hour (31.2 a day). Th e Kenmore has a full-function remote control with sleep mode, timer, fan speed, and temperature controls, but is non-smart (neither are the LGs, for the record).

The Kenmore Elite 77060 fits vertical sliding windows that are a minimum of 14 in. high and 23-36 in. wide (the A/C unit itself measures 15.5 x 18.5 x 13.4 in.). It has no vent though, unlike the LGs.

The Kenmore Elite includes adjustable accordion side panels, is Energy Star certified with Energy Saver mode, 8-way air direction, 3 cooling speeds, 3 fan speeds, and a washable filter with check filter alert. The Sleep Timer lasts just 7 hours and this model may be a little noisy, so might not be ideal for use in the bedroom if you like your quiet.

The Soleus Air® WM1-06E-02 is an inexpensive (c$169) 6,000 Btu window air conditioner that can cool a room up to 275 sq. ft. It has an Energy Star rating of 12.1, three fan speeds in cooling or fan-only modes, a digital thermostat and remote control with screen. The MyTemp sensor on the remote control is a smart feature that targets air to cool your location within a room, and this model also features a 24-hour timer, energy saver mode, and sleep mode.

The Soleus Air also has an auto restart mode in case of power outages, a dry mode to turn the air conditioner into a stand-alone evaporative dehumidifier (up to 30.48 pints per day or 1.27 per hour), and a washable and reusable filter. Soleus offers a warranty of 24 months for components and 60 months for the compressor, which is more generous than most in the industry. The Soleus Air weighs 46.3 pounds and measures 15.5 in. deep, 12.625 in. high, and 18.625 in. wide.

Because these models are lighter than the more powerful units that follow, they don’t have a slide-out chassis, so you may well need some help holding the unit during install.

All in all, your best bet in this category is probably to try to snap up the LG LW6018ER before they sell out. After that, prepare to stump up a little more for the LG LW6019ER or consider the slightly cheaper Kenmore Elite 77060. Soleus Air are a smaller company, but offer a much better warranty, so if you can track one down and are looking for a three-in-one A/C, dehumidifier, and fan, this is a great option, especially if you’re on a tighter budget.

A/C units with 8,000-9,999 Btu

In the 8000-9999 Btu range, guess what? LG take top place again.

Air conditioner brand/modelBtuCEER* Variable Speed CompressorAnnual Energy Use (kWh/yr)
LG- LW1019IVSM9,50013.8Yes516.3
LG – LW8019ER8,20012.5No480.0
LG – LW8017ERSM8,00012.0No500.0

*CEER is the Combined Energy Efficiency Rating.

The LG LW1019IVSM has a 9,500 Btu cooling capacity and is a variable speed compressor, meaning that it is more energy efficient than comparable single speed compressor units. Unsurprisingly, this one exceeds the Federal Standard by 26.61%.

The LW1019IVSM has smart connectivity and can be controlled via remote, wi-fi, smartphone app., and through Alexa and Google Assistant. The only downside of this unit is that it is not yet on the market! The Energy Star rating was granted just this month and the company doesn’t yet list the model on its site, so I’m anticipating the rollout soon, hopefully in time for the summer months. Watch this space!

In the meantime, if you need an A/C in this range right now, consider the LG LW8017ERSM, a similar model albeit with a lower CEER (12.0) and cooling capacity (8,000 Btu). It can be controlled via the control panel, remote, smartphone app., Alexa and Google

This model weighs 58 pounds and measures 19 9/16″ x 12 3/8″ x 19 3/8″. It can dehumidify 2.2 pints per hour (52.8 in a day), and is ideal for cooling around 342 sw. ft. This one uses the slightly more eco-friendly R32 coolant, has an auto restart option and energy saver mode, and a 24-hr programmable timer.

If your budget is a little higher and you prioritize a little extra power over smart functionality, go for the LG LW8019ER. This model has almost all the same features as the 8017ERSM model, minus connectivity, but offers 8,200 Btu and has a 12.5 CEER.

A/C units with 10,000-11,999 Btu

Interestingly, in the 10000-11999 Btu range, LG don’t get top place and energy efficiency falls quite precipitously.

Air conditioner brand/modelBtuCEER* CompressorAnnual Energy Use (kWh/yr)
GE – AED10AV10,00012.1No619.8
GREE – GJC10BR-A3NRNF2A10,00012.1No619.8
GREE – GJC10BR-A3NRNF2B10,00012.1No619.8
Emerson Quiet Kool – E*RC10RE110,00012.0No625.0
Kenmore Elite – 580.7710771010,00012.0No625.0

*CEER is the Combined Energy Efficiency Rating.

The GE AED10AV (and the GE AEM10AV) air conditioner is Energy Star qualified and has a 10,000 Btu cooling capacity, digital thermostat, remote control, wi-fi connectivity, and quiet mode. It is relatively easy to install, has a washable filter, and uses the R410-a coolant.

This model weighs 71 pounds and measures 19.3437 in. wide, 15.75 in. high, and 21.25 in. deep. It requires 115 Volt connection and uses 619.8 kWh/yr, with a 12.1 CEER. The GE can dehumidify 3 pints an hour (72 per day), which is pretty good for a smaller capacity A/C.

Unfortunately, GE no longer seem to be manufacturing either the AED or AEM 10AV models, so if you like the look of this one, grab it while you can. The other top two air conditioners (both by GREE) listed by Energy Star as the most energy efficient in this category don’t appear to be available for sale at all anymore.

Kenmore Elite 77107 10,000 BTU Smart Room Air Conditioner. This one has a 12.0 CEER and can be controlled via a smartphone app, remote control, or control panel as well as by Alexa voice control. It costs around $359, making it a little pricier than other A/Cs with similar capacities but no ‘smart’ functionality. Given that most of the negative reviews of this model focus entirely on how the app. is dysfunctional, you may want to go with a different model if smartphone compatibility is a priority.

The Kenmore Elite requires a minimum window width and height of 27 x 16 inches and a maximum width of 39 inches. The unit itself measures 22.187 inches deep, 15 inches high, and 23.625 inches wide. It is designed to cool spaces up to 450 sq. ft. but doesn’t have a sleep mode, so is probably best for the living room rather than bedrooms.

The Emerson Quiet Kool – EARC10RE1 is probably the most cost-effective option in this category. It has a 10,000 Btu cooling capacity, a CEER of 12.0 and an EER or 12.1, offers 8-way airflow louvers and a 24-hour programmable timer. It costs less than the Kenmore at around $329, largely because it doesn’t bother with any smartphone app. controls and such.

The Emerson has a washable filter, remote control, Eco mode and a sleep mode as well as a low voltage startup to conserve energy and save money. This model also features an auto restart in case of a power failure and, as the name suggests, the Emerson Quiet Kool runs a little quieter than some other models (not in Eco mode, though, where it turns on and off). It weighs 63.9 pounds and measures 19.8 x 21.5 x 14.6 inches

All this said, my top recommendation in this category is… the LG from the previous category. Yep, with its much better energy efficiency rating and greater availability, the LG – LW1019IVSM with a 9,500 Btu capacity just makes a lot more sense than the lackluster options at 10,000 Btu. You’re better off going with the slightly smaller, but more efficient, model and installing a ceiling fan and some nice solar blinds.

A/C units with 12,000-13,999 Btu

In the 12,000-13,999 Btu range, the winners for energy efficiency are… well, nobody really. The Energy Star website is not a useful starting point if you’re looking for something in this range as almost every unit listed has a CEER of just 12 and the site spits these out seemingly at random.

There are many low name recognition brands in this list, including Soleusair, Cool Living, and Toscana Air, alongside bigger brands like GE, Frigidaire, Danby, and LG.

Air conditioner brand/modelBtuCEER* Variable Speed CompressorAnnual Energy Use (kWh/yr)
Soleusair – WS1-12E2-0212,00012.0Unclear (likely not)750.0
COOL LIVING – CLYW-35C1A-HA09AD12,00012.0Unclear (likely not)750.0
Toscana Air – 57H-ID0-MWEUK12CRN112,00012.0No750.0
LG LW1217ERSM12,00012.1 (EER) (no CEER listed)No750.0
LG LW1216ER12,00012.0 No750.0

*CEER is the Combined Energy Efficiency Rating.

The Soleus Air 12,000 Btu window-mounted air conditioner is easy to install and simple to operate. It has remote control capability, digital controls and a programmable thermostat and timer as well as an auto start mode to turn it back on after a power outage. The filter is washable and reusable and there is an alarm setting to remind you when to clean it.

This 12,000 BTU air conditioner is designed to cool a room up to 575 sq. ft. and also has a dehumidifying ‘Dry’ mode that can remove up to 52 pints of water a day to help reduce mold and mildew. There are 6 modes in total – cool, dry, fan, auto, sleep, energy saver – and 3 air speeds – low, med, high – with 4-way directional air louvers and fresh air vent.

This model requires a standard 115-Volt electrical outlet and fits windows with minimum width of 28.13 in. (41.75 in. maximum) and minimum height 18.7 in. A window mounting kit is included.

Unfortunately, this model uses R410-a coolant, which has higher global warming potential than R32 coolant. However, R410-a is a very effective coolant which may have a net advantage for reduced greenhouse gas emissions by lowering energy consumption overall (R).

The Cool Living CLYW-35C1A-HA09AD 12,000 Btu air conditioner has the same CEER rating as the Soleus and uses the same amount of energy but is less widely available. It measures 30.25 in. high, 25.75 in. wide, and 19.75 in. deep, and weighs just over 116 pounds. The small number of online reviews suggest that this unit may be tricky to install, with poor instructions provided by the manufacturer. This is hard to confirm, however, given that there is very little online about this unit. Even the manufacturer’s website is woefully bereft of useful information. As such, I wouldn’t recommend buying this unit unless it’s your only option.

The Toscana Air – 57H-ID0-MWEUK12CRN1 is another enigma, with little online other than the Energy Star rating. Again, the lack of information makes me hesitant to recommend this unit.

Even LG aren’t doing that great in terms of energy efficiency in this Btu range. One of their best options is the LG LW1217ERSM 12,000 BTU 115V Window Mounted Wi-Fi Control Air Conditioner. This is a best-seller on Amazon, has a 2017 Energy Star EER of 12.1 (the Energy Star website says 12.0 for 2015 CEER), and offers wi-fi and smartphone control. It is a top pick from Consumer Reports with a score of 85, on the basis of testing done on another LG, the LW1216ER, which is not a ‘smart’ A/C but is also rated a 12,000 Btu.

The LG LW1217ERSM can dehumidify up to 3.8 pints per hour or 91.2 per day (compared to the Soleus Air’s 52 pints), and is suitable for cooling a room up to 550 sq. ft. This model weighs in at 81 pounds, and the unit measures 22.2 in. long by 23.6 in. wide and 15 in. tall, to fit a window width of 17 in. minimum (39 in maximum), and a minimum window height of 16 in. This LG uses plastic insulation instead of Styrofoam, which is better for avoiding mold and mildew build-up. It is also quieter than other similar units if properly installed.

The LG LW1216ER costs a little less but is the model actually tested by Consumer Reports. It has all the same features of the LG LW1217ERSM minus the wi-fi and smartphone compatibility.

The Frigidaire FFRA1222U1-12,000 BTU 115V Window-Mounted Compact Remote Control Air Conditioner is another Amazon bestseller and has some great reviews, but it is not Energy Star certified, so there’s no decent information on its performance.

Given that the Frigidaire is very similar to the LG model in most respects, including dehumidifying capacity and cooling capacity, as well as smartphone and remote function, if you’re looking for an A/C with a capacity of 12,000, I’d suggest you go for the Energy Star rated LG LW1217ERSM.

If your budget stretches to it, however, I’d recommend you opt for a 14,000 Btu unit from LG instead. The energy efficiency is far better, and your running costs will be lower overall. If you’re not convinced you need a 14,000 Btu unit, you might consider a 9,500 Btu LG instead, paired with a nice ceiling fan and some other alternatives to air conditioning.

A/C units with 14,000-19,999 Btu

Things improve quite significantly in terms of energy efficiency once we bump up to 14,000-19,999 Btu. This means that if your choice is between a 14,000 Btu model or a 12,000 Btu model, you’re probably better off with a variable speed 14,000 Btu LG than a less efficient 12,000 Btu that uses more power to do less.

Arguably, efficiency improves in this category because LG step in again. Energy efficiency ratings rise to 14.7 for two models with variable speed compressors.

Air conditioner brand/modelBtuCEER* Variable Speed CompressorAnnual Energy Use (kWh/yr)
LG – LW1517IVSM14,00014.7Yes714.3
LG – LW1817IVSM18,00014.7Yes918.4

*CEER is the Combined Energy Efficiency Rating.

The LG – LW1517IVSM with variable speed compressor/dual inverter is the top pick in this category. It is more energy efficient than other models, can cool around 800 square feet of space, runs quietly, and has remote control functionality and is smartphone compatible. If a power outage occurs, this model has an auto restart function to get things going again without you having to lift a finger.

This model also has four-way air direction, so you can tailor it to the needs of your space, and features a 24-hour programmable timer and sleep mode. It even looks pretty nice in the window and can be run on just 120 volts, unlike most other high-powered A/Cs. It weighs 112 pounds and measures 27.9 x 27.3 x 20.7 inches. The slide in-out chassis makes for easier and safer installation.

This model is priced at around $489 and uses a whopping 37.38% less energy than the U.S. Federal Standard!

The 18,000 Btu LG-LW1817IVSM with variable speed compressor also uses 37.38% less energy than the U.S. Federal Standard, is smartphone and wi-fi enabled, runs quietly, has auto restart, four-way air direction, a 24-hour programmable timer, sleep mode, and is priced at around $600. This one requires a 240 volt outlet, however, unlike the 14,000 capacity model.

A/C units with 20,000 Btu and above

Above 20,000 Btu, your best bet is, again, LG. However, only their LG – LW2217IVSM model gets a rating above 10.4, so pickings are slim in this range. Unless you buy the LG, you may well be better off installing central air or taking a serious look at why a 20,000 Btu seems necessary. Is your room really 1,000 square feet in size? Are there other ways to keep it cool, such as solar blinds, more thermal mass from a dark concrete or stone floor, or planting deciduous trees outside to create a shady canopy?

Air conditioner brand/modelBtuCEER* Variable Speed CompressorAnnual Energy Use (kWh/yr)
LG – LW2217IVSM22,00014.5Yes1137.9
Friedrich – YL24N35D-A24,30010.4Yes1752.4
TGM – MWEUT24BR (Not EnergyStar Certified)25,00010.3No1820.4

*CEER is the Combined Energy Efficiency Rating.

The LG – LW2217IVSM is a popular high capacity window air conditioner. It has a dual inverter compressor that makes it a lot less noisy than other high capacity models and also makes it a lot more energy efficient (as you can see from the table above). Typical decibel levels for this unit are 62/59/55/44 indoors for High/Mid/Low/Sleep settings respectively. Noise levels are significantly higher outside at 67/65/63/55 for the same settings.

With 4-way air direction and the capacity to cool around 1300 square feet, this is a great option for larger rooms and open plan spaces. Tech nerds will also like this unit as it boast Alexa and Google Assistant compatibility – yep, you can control the unit by voice alone. There’s also remote control functionality and smartphone compatibility, a 24-hour programmable timer, auto restart option, and energy-saver function. This model even has a filter alarm, so you know when it’s time to clean the filter to maintain efficiency.

The only real downside to this model is that it doesn’t have heating as well as cooling capacity, unlike the Friedrich. However, the LG weighs in at 110 pounds, while the Friedrich weighs in at over 200 pounds. For either model, despite their slide in-out chassis designs, you’re probably going to need some help installing it safely.

The LG model measures 26.2 x 25.9 x 17.7 inches and requires a 230 volt outlet. One thing to note about this model is that it uses R32 as a coolant. This type of coolant has a much lower global warming potential than most other refrigerants currently in use and has a lower risk of acute toxicity. However, it does warrant a California Prop 65 caution warning because it is made using a chemical called dichloromethane (methylene chloride). R32 itself is difluoromethane and is thought to contain no more than 0.003% dichloromethane after production (R). The Friedrich uses R410-a coolant, which has a higher global warming potential but may be more energy efficient overall.

There’s very little information available on the brand and model listed by Energy Star as the number 3 pick for energy efficiency in this category. Indeed, TGM’s model of A/C doesn’t seem to be available for sale in the U.S. and doesn’t even meet the criteria for Energy Star certification as it only exceeds the Federal Standard for energy use by 9.57%, not the required 10%.

Overall, then, the LG – LW2217IVSM is easily the top pick in this category as it is more efficient, uses more eco-friendly coolant, and costs about three times less than the Friedrich (c$600 vs. c$2,000). The Friedrich models also seem to have a lot of issues that are hard to resolve because of the scarcity of parts and authorized repair and service personnel, while LG garner a lot of positive reviews and seem to be robust and durable.

Other top tips for staying cool this summer

Other great ways to stay cool this summer include popping your eco-friendly pillowcases and sheets in the freezer a half hour or so before bed. That way, they’ll be nice and cool when you get into bed, which will help you drift off and sleep well. You could also use your hot water bottle as a cool water bottle by throwing some ice and cold water in there before bedtime to help keep your sheets cool.

You can also keep indoor air temperature down by turning off and unplugging laptops, televisions, and other electronics that pump out heat even when they’re on standby. If you have the option, avoid using a dryer during these warmer months. Line dry when you can or set up a clothing airer with damp clothes by an open window and run a fan next to it as a natural air conditioner.

And, if you live in a city apartment and have a balcony that gets uncomfortably hot in summer, consider using bamboo as a natural screen. This will help block direct sunlight to help keep your apartment and balcony cool, and also acts as a privacy screen and air filter, all while looking great!

One final tip is to check for rebates on Energy Star certified air conditioners where you live. After all, saving some cash can help you keep your cool as the cost of living rises.

Do you have any top tips for alternative air conditioners or a recommendation for an A/C you love? Let us know in the comments!