You don't need me to tell you how hard it is to get anything done when you're sweating away in a hot, humid room. A good window air conditioner is a must in these situations. Fortunately, most of the best air conditioners are Energy Star-certified to not only cool your room but to also do it efficiently and economically.
One of the most efficient ACs available is the LG Dual Inverter Smart Window Air Conditioner, which uses state-of-the-art inverter technology to keep your energy costs down while keeping your room at a comfortable temperature.
I've tested dozens of ACs for our guides to the best ACs, and this one took home the title of "best for large rooms" after our rigorous evaluation. I've also used this unit for more than a year now in my own home; below are my experiences with it. (We recommend window ACs versus portable ACs for most people, but if you can't fit a window unit in your come, check out our guide to the best portable air conditioners.)
Design and specs
Btu: 14,000
Recommended room size: 800 square feet
Window opening requirements: 16 inches vertical by 27 to 39 inches wide
CEER: 14.7
Energy Star-certified: Yes
Warranty: 1 year
Smart connectivity: Yes
Extras: Dehumidifying, fan, remote control, foam seals, side curtain insulation, window security brackets, delay on/off, smart home compatibility
The LG Window Air Conditioner (model number LW1517IVSM) has a 14,000 Btu capacity, which makes it ideal for rooms of about 800 square feet. It's Energy Star-certified with a Department of Energy-tested combined energy efficiency ratio (CEER) of 14.7, which makes it one of the most efficient air conditioners available. The estimated yearly energy cost is $68.
The appliance has four modes of operation: standard (with four cooling speeds), energy saver, fan, and dehumidifying. It can be controlled via a smartphone app or the included remote control, though the app offers more functionality.
Setup process
You can use onboard controls to set the temperature and fan speed, but the AC also comes with a remote control and smartphone app. James Brains/Insider
Everything you need for installation is in the box, including window security brackets and insulating foam to provide a good seal. You'll need to use your own tools for the installation. In particular, it's helpful to have Phillips-head and flat-blade screwdrivers, an adjustable wrench, a level, a tape measure, a knife, scissors, and a pencil on hand.
Installation was a major pain and took me two hours. Here are the steps:
Unscrew the cabinet from the AC and remove the innards.
Put window sash seals on the window.
Attach the curtains to the unit, which involves awkwardly screwing in eight screws that don't line up well.
Put the cabinet in the window.
Install the sill brackets.
Screw the cabinet into the sill brackets.
Stretch the curtains out to fit the window and screw them in.
Reinstall the AC's innards.
Add the foam strip to the gap between the window panes.
Install the window security bracket.
Install the heatproof foam insulation over the curtains.
Attach the face, which involves holding it awkwardly and making sure the vent and cord stuck through and that and everything was lined up just right.
All this to say, I recommend having a friend help you with the heavy lifting.
After the grueling installation process, I was relieved to find that connecting the AC to the LG SmartThinQ app was seamless. It paired with my Android phone in no time, and I found the controls useful. You can set a schedule for when your AC runs, adjust the thermostat, and more.
Review of the LG Dual Inverter Air Conditioner
The LG LW1517IVSM is special because it utilizes dual inverter technology. Most air conditioners turn the compressor on or off to regulate the temperature. Inverter ACs feature variable-speed compressors that make micro-adjustments to the temperature. In Department of Energy's tests, this LG model achieved efficiency scores 25% better than the minimum Energy Star requirement.
But, how does it perform? When I test ACs, I set the heat in my house to 75 degrees and then blast the AC on high to see how much it reduces the heat in a 650-square-foot room. This LG model performed better than any other AC I've tested, reducing the temp by 3.3 degrees in an hour.
Additionally, I used the LG LW1517IVSM all summer in our family room, where we spend most of our time. It kept us perfectly cool in the humid Michigan heat. We typically use "energy saver" mode, which takes full advantage of the inverter technology.
Installation was a pain, but once it was up and running, the AC cooled the room quickly. James Brains/Insider
Another reason why this model is excellent for our family room is its quiet operation. On high it registered 53 decibels, which is only slightly louder than your average home or quiet office. Plus, the transition between motor speeds was smooth. I never noticed any jolting, obnoxious sounds during my months of use.
Cons to consider
The biggest negative with the LG LW1517IVSM Window Air Conditioner is the installation process. And, in Michigan, it gets so cold you can't leave window ACs in place during the winter. So, I have to relive the trauma of moving this 100+ pound behemoth each fall and spring.
I appreciate how the unit connects easily to my phone. Unfortunately, I couldn't get it to connect to Amazon Alexa. I also wish I could sync the unit with my ecobee SmartThermostat, but without Alexa as an intermediary, I wasn't able to get that to work either.
You'll also have to make sure you have windows large enough to accommodate this beast. Measure and make sure you have a width of at least 27 inches but no more than 39 inches. The window should also open to a height of 16 inches.
What are your alternatives?
I've tested dozens of ACs over the years, and despite the above cons, I still think the LG Dual Inverter Smart Window Air Conditioner is among the best. That's why I made it a top pick in our guide to the best air conditioners. That said, it's best if you have large windows, a large space to cool, and are willing to front-load the cost of an expensive air conditioner (though it will save you money in the long run).
If you're looking for similar energy efficiency that works for smaller rooms and windows, the only unit I think comes close to achieving the energy efficiency of the LG model is the Midea U Inverter. It's a lot easier to install and has a unique design that allows you to open and close your window as needed while it's installed.
If you're debating between a window AC vs a portable AC, we think window units are best for most people. However, if you don't have windows to accommodate a traditional unit, check out our guide to the best portable air conditioners.
The bottom line
The LG LW1517IVSM is one of the best window air conditioners you can buy. It's efficient, powerful, quiet, and easy to use.
Based on my testing, I think the LG air conditioner is the best for most people. James Brains/Insider
If you have a room you want to cool that's 800 square feet or so and that has a double-hung window at least 27 inches wide, the LG Dual Inverter AC is your best option for getting the job done. There are several ACs out there that cost less than this LG unit, but long-term, you will save on energy costs with this model.
If you don't have $550 available to purchase an AC, many sellers offer plans with affordable monthly payments and 0% APR for those who qualify.
What model should you get?
While it might be tempting to pick the most powerful model, we recommend choosing the right air conditioner for your room size. If the room is too big, the AC will constantly run on top speed, which will cause your utility bills to skyrocket. If the room is too small, it will feel cold and clammy as the room cools faster than the AC can wick the moisture away.
Fortunately, the LG Dual Inverter is available in several sizes:
The LG LW1019IVSM is ideal for 450-square-foot rooms.
The LG LW1517IVSM is best for 800-square-foot rooms. (This is the model we tested.)
The LW2217IVSM is best for rooms of 1,300 square feet.
Pros: Smartphone app and remote control, uses energy-efficient dual-inverter technology, quiet operation, did the best job of cooling my home of any AC I've tested
Cons: Can only be installed in windows that are at least 27 inches wide, underwhelming warranty, pain to install
Check price at WalmartJames Brains Senior Reporter, Business Insider Reviews James is a Senior Reporter for Business Insider Reviews, specializing in sleep, HVAC, and kitchen appliances. He has tested more than 90 mattresses from startups like Casper and legacy brands like Tempur-Pedic, using his background in experimental psychology to develop objective tests and evaluate comfort, support, motion transfer, and more. He authors our guide to the best mattresses. In addition to being Business Insider Reviews' mattress expert, James has extensively covered air fryers, bidets, air conditioners, air purifiers, and anything you put on your mattress, including weighted blankets and pillows.He's a multifaceted writer who has covered everything from health and fitness to consumer technology. His mission is to help people get the most value for their money by guiding them in making informed buying decisions.James lives in Lansing, Michigan, with his wife, two kids, and a kitty. When James isn't testing products and writing for Business Insider, he runs a popular local Facebook group, Lansing Foodies; hosts a local news segment called Foodie Friday; and puts on the Olive Burger Festival.Contact info: jbrains@businessinsider.comLearn more about how our team of experts tests and reviews products at Insider here.Learn more about how we test kitchen products. Read more Read less
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LG LW1517IVSM Dual Inverter Smart Window Air Conditioner Check price at Walmart 
James Brains Senior Reporter, Business Insider Reviews James is a Senior Reporter for Business Insider Reviews, specializing in sleep, HVAC, and kitchen appliances. He has tested more than 90 mattresses from startups like Casper and legacy brands like Tempur-Pedic, using his background in experimental psychology to develop objective tests and evaluate comfort, support, motion transfer, and more. He authors our guide to the best mattresses. In addition to being Business Insider Reviews' mattress expert, James has extensively covered air fryers, bidets, air conditioners, air purifiers, and anything you put on your mattress, including weighted blankets and pillows.He's a multifaceted writer who has covered everything from health and fitness to consumer technology. His mission is to help people get the most value for their money by guiding them in making informed buying decisions.James lives in Lansing, Michigan, with his wife, two kids, and a kitty. When James isn't testing products and writing for Business Insider, he runs a popular local Facebook group, Lansing Foodies; hosts a local news segment called Foodie Friday; and puts on the Olive Burger Festival.Contact info: jbrains@businessinsider.comLearn more about how our team of experts tests and reviews products at Insider here.Learn more about how we test kitchen products. Read more Read less