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How to Select the Best Window Air Conditioner

by on June 04, 2019
in Health and Home, Home Improvement, Tips & How-Tos :: 25 comments

Techlicious editors independently review products. To help support our mission, we may earn affiliate commissions from links contained on this page.

There is no need to suffer through summer heat when inexpensive, energy-efficient air conditioners are widely available. Since October 26, 2015, all ENERGY STAR rated room air conditioners have been required to meet a new standard, ENERGY STAR 4.0, that sets maximum power use at 10% less than older models following the 2014 guidelines. And, when used to provide cooling only where they're needed, room air conditioners are less expensive to operate than central units. This guide will help you find the model that is right for you.

Energy efficiency of room air conditioners

A room air conditioner's efficiency is measured by the energy efficiency ratio (EER). The EER is the ratio of the cooling capacity (in British thermal units [Btu] per hour) to the power input (in watts). The higher the EER rating, the more efficient the air conditioner. Each increase of 1.0 on the EER scale represents a 10% increase in energy efficiency.

When buying a new room air conditioner, information about the EER can be found on the EnergyGuide label for the unit. Look for an EER of at least 12 and the ENERGY STAR label. Earning the ENERGY STAR means a product meets strict energy efficiency guidelines set by the U.S. Environmental Protection Agency and the U.S. Department of Energy. 

Properly Sizing a Room Air Conditioner

The required cooling capacity for a room air conditioner depends on the size of the room being cooled. Room air conditioners generally have cooling capacities that range from 5,500 Btu per hour to 14,000 Btu per hour.

Many people buy an air conditioner that is too large, thinking it will provide better cooling. However, an oversized air conditioner is actually less effective — and wastes energy at the same time. Air conditioners remove both heat and humidity from the air. If the unit is too large, it will cool the room quickly, but only remove some of the humidity. This leaves the room with a damp, clammy feeling. A properly sized unit will remove humidity effectively as it cools.To figure out which size unit is best for your cooling needs, see the Air Conditioner Cooling Needs Calculator below.

Other factors to consider when buying

Verify that your home's electrical system can meet the unit's power requirements. Room units operate on 115-volt or 230-volt circuits. The standard household receptacle is a connection for a 115-volt branch circuit. Large room units rated at 115 volts may require a dedicated circuit and room units rated at 230 volts may require a special circuit. If you are mounting your air conditioner near the corner of a room, look for a unit that can direct its airflow in the desired direction for your room layout. If you need to mount the air conditioner at the narrow end of a long room, look for models that have a “turbo” fan mode that can drive air further into the room. Other features to look for:

  • A filter that slides out easily for regular cleaning
  • Logically arranged controls
  • A digital readout for the thermostat setting, and
  • A built-in timer.

Do you need a smart air conditioner?

For those that keep to a regular schedule and don't have smart home devices installed in their home, a timer will help save money (about $100 on the air conditioner itself and your energy bill) and save you from coming home to a hot, stuffy home. For many, though, the ability to control a room air conditioner from anywhere can be a huge help and cost savings, especially if you don't stick to a schedule. And, you can connect them to other smart home devices so they fit seamlessly into your daily routine.

Our Picks

Small rooms (up to 150 square feet)

Frigidaire FFRE0533U1 room air conditioner

The Frigidaire FFRE0533U1 ($309.00 on Frigidaire, check price on Amazon), rated at 5,000BTU, gets high marks for its cooling and dehumidification capabilities of up to 1.1 pints per hour. The unit, which has an EER of 12.2, two cooling and three fan speeds, a 24-hour programmable timer, built-in thermostat with digital temperature readout, remote control and a four-way adjustable vent to direct air flow.

Medium rooms (up to 350 square feet)


The LG LW8016ER ($279.99 on LG, check price on Amazon) delivers 8,000 BTUs, enough to cool a room up to 350 square feet, with an EER of 12.1. The unit has 3 fan speeds, three cooling speeds, and 2-way slanted louvers that direct airflow in an upward, circular motion for even cooling. You can create a custom 24-hour schedule or use the dedicated remote control. And, it has a built-in dehumidifier that can remove up to 2.2 pints per hour. 

Installing and operating your room air conditioner

A little planning before installing your air conditioner will save you money and energy. The unit should be level when installed so that the inside drainage system and other mechanisms operate efficiently. If possible, install the unit in a shaded spot on your home's north or east side. Direct sunshine on the unit's outdoor heat exchanger decreases efficiency by as much as 10%. You can plant trees and shrubs to shade the air conditioner, but do not block the airflow.

Don't place lamps or televisions near your air-conditioner's thermostat. The thermostat senses heat from these appliances, which can cause the air conditioner to run longer than necessary.

Set your air conditioner's thermostat as high as is comfortably possible in the summer. The less difference between the indoor and outdoor temperatures, the lower your overall cooling bill will be. Don't set your thermostat at a colder setting than normal when you turn on your air conditioner; it will not cool your home any faster and could result in excessive cooling and unnecessary expense.

Set the fan speed on high, except on very humid days. When humidity is high, set the fan speed on low for more comfort. The low speed on humid days will cool your home better and will remove more moisture from the air because of slower air movement through the cooling equipment.

Also, consider using an interior fan in conjunction with your window air conditioner to spread the cooled air more effectively through your home without greatly increasing electricity use. We like the Haiku Home L Series 52-inch Indoor/Outdoor fan ($688.00 on Big Ass Fans, check price on Amazon), which provides coverage for indoor or outdoor space of up to 15 by 15 feet. It has a built-in LED light (40-watt equivalent) with 16 brightness settings. And, with the optional Haiku WiFi module ($50 on Big Ass Fans, WiFi included in models on Amazon), you can use your smartphone, Alexa or Google Assistant. 

And, if you can't install a room air conditioner in your window, consider a portable unit. You can check our picks for portable air conditioners.

Updated with new picks 6/4/2019

[Image credit: Window air conditioner via BigStockPhoto, Frigidaire, LG]

Air Conditioner Cooling Needs Calculator

To determine the correct size Air Conditioner for your room, follow these easy steps:

  1. Determine the square footage of the area to be cooled.
  2. Using the square footage and the chart below, determine the correct cooling capacity. Cooling capacity is measured in British thermal units (BTUs) per hour.
  3. Make any adjustments for the following circumstances:
  • If the room is heavily shaded, reduce capacity by 10 percent.
  • If the room is very sunny, increase capacity by 10 percent.
  • If more than two people regularly occupy the room, add 600 BTUs for each additional person.
  • If the unit is used in a kitchen, increase capacity by 4,000 BTUs.
  • For the purpose of this chart, rooms that are connected by permanently open entryways wider than five feet ought to be considered as one room and their square footage should be combined.
Area to be Cooled
(Square Feet)
Capacity Needed
(BTUs per Hour)
100 to 150 5,000
150 to 250 6,000
250 to 300 7,000
300 to 350 8,000
350 to 400 9,000
400 to 450 10,000
450 to 550 12,000
550 to 700 14,000
700 to 1000 18,000
1000 to 1200 21,000


Discussion loading

Cooling a dog house

From Kevin G. on June 10, 2014 :: 2:43 pm

We have a 6’d x 8’w x 7’h (interior dimensions) dog house for our great dane and other large dog. The dogs are kept outside during the day and we allow them in our house when we are home from work.

We insulated the dog house for the winter and added a space heater. This works well as they are both short haired dogs.

Our question is what is recommended to keep them cool in the summer. It’s already in the nineties here. We were considering an A/C unit but that may be overkill given the size of the room.


There are AC units for outdorr sheds/doghouses

From Josh Kirschner on June 11, 2014 :: 8:21 am

There are AC units made specifically for outdoor applications like a shed or doghouse. We covered one of the models in our story on Summertime Tech for Your Pet. You can learn more here:


Amazing product reviews.

From Audrey Miller on October 01, 2014 :: 11:07 am

I can’t agree more with your opinions and reviews. All these are definitely remarkable and needs to be noted. This can surely help those who’re having problems with choosing the right air conditioner for their home. This is a must share.


AC That "Samples" The Air?

From Richard Longley on March 02, 2015 :: 1:02 pm

The trouble with all room air conditioners that I have owned is that when you run them in the Energy Saver mode they never seem to turn back on until the room becomes over heated.  I have a room heater that once it warms the room and shuts off it “samples” the room air temperature every 15 minutes by running it’s fan for a few seconds.  That feature works great. Is there a room air conditioner that has this air temperature sampling feature?  If there isn’t there should be.


Energy saver mode

From Ernie on June 19, 2017 :: 7:44 pm

Get an LG room air conditioner. There energy saver setting works!!


night time use

From curiousburke on July 20, 2015 :: 12:06 am

I like the easy way to calculate AC size with just a few modifiers, but it seems like there is one missing.  How would you modify the calculation in the case that you only plan to us the AC at night in a bedroom.


nice share

From toko on October 14, 2015 :: 5:27 am

thanks for the article..tremendous review.great worked! now i deeply understand about air conditioner.i try to figure out lately until i find your blog.god bless u..i will bookmark your site


Great Reviews

From Citicool on June 30, 2016 :: 11:49 pm

Thanks for the reviews! Great tips for those looking to get a window air conditioner for their home as well.


Great Article

From Barbera Peters on July 12, 2017 :: 10:49 am

I wanted to thank you for your information on choosing an air conditioner. I agree that the size of the room determines the size of the machine. You make a really great point on looking at the controls arrangement and checking for built in timers.Since the summer is finally hear and my apartment has zero air conditioning this is my first time buying an air conditioner. I wasn’t sure what to look for but this really helped. Thanks for the great advice.


Great post...!

From Ramayan Supply on August 12, 2017 :: 7:07 am

Hey Suzanne Kantra, Great post. I read your article and the tips which you mentioned here…I shared the same tips with my friend, who was looking for Air conditioner 1 week ago. He is impressed and found the right air conditioner for his home. Thanks for sharing information.!


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Multi room window units

From Ron Escamillo on August 30, 2017 :: 8:18 pm

I have a 500 square-foot bachelor apartment attached to a large three car garage that I converted into a one bedroom apartment. It’s now 650 sq ft. with a kitchen, a living room and a bedroom.  I think it’s too small to install central air. Is there a window unit large enough to cool off three rooms?


There are air conditioners that

From Suzanne Kantra on August 31, 2017 :: 9:45 am

There are air conditioners that can cool off spaces that large (look for a 1400 BTU model), but the issue will be getting the air circulate through the 3 rooms. You might be able to do it with fans, but you’re probably better off purchasing units for each room.


HELP! 5500 BTU Window Unit on 100W Solar Panel?

From Jess on April 17, 2018 :: 11:51 pm

Hi! My landlord will not allow us to put a window air-conditioner in even though we pay all the utilities. It gets up to 108 degrees in summer, I have multiple skylights, and work from home. Is it possible to run a unit on a 100W Solar Panel with 8.5 amp for 12-volt battery? Or is there anyone who has set any portable or window air-conditioning system up on alternative energy at all? If so, could you provide me any specs? IE: What maximum BTU’s I can operate, What type/size of inverter I’d need, and if I can plug inverter directly into panel or amp thing or if I need the battery in between the two. I’m sorry - I have googled the crap out of this question and cannot find a straight answer (or at least one that I comprehend—not my field of brilliance…)

I’m not worried about how many hours a day it will run it, I’m just curious if it will at all. (I think we are going to go ahead and use this part time and if extra is needed just plug it in and use the electricity (since we pay for it!!) but it needs to be “functional” for him… I know, deceitful, but I can’t afford to set his house up with solar power and I’m desperate to be able to work in cooler conditions.

Thank you so much for any input!


Go with portable

From Josh Kirschner on April 18, 2018 :: 8:32 am

That’s pretty crappy of your landlord, and it may even be illegal, depending on where you live. You may want to check into that angle.

In any regard, if his objections are one of safety from window units falling out or damaging the window, perhaps you should consider a portable unit. They’re around the same price of a window unit and you can move them from room to room, so you need fewer of them. Plus, your landlord may not even notice you have it, since it just requires a small venting space in the window when operating.

A quick search on Amazon will give you a ton of options, some under $300:

If your landlord is concerned about the house’s circuitry being able to deliver the necessary current for your AC and other items, then the solar option may work. Though it will be far more expensive than a portable unit, require installation on the roof (which your landlord would also likely object to) and not give you the portability.


For more options, check out

From Suzanne Kantra on April 18, 2018 :: 8:42 am

For more options, check out our portable air conditioners guide:


Multiple Features

From Maya on May 04, 2018 :: 7:02 am

Thanks for sharing an informative article. If you really want to make your life more comfortable then get Cielo Breez and use with your window AC.


Recharge Window AC Conditioner

From Salina Hocutt on August 02, 2018 :: 8:23 am

Thank you for sharing this wonderful article. I have one window AC in my bedroom which have 3 years old. Now, its cooling is less. So, I should refresh it?


I wish I had a better AC unit!

From JK on August 30, 2018 :: 3:56 pm

This is the summer I wish I had gotten a new AC unit. I’m dying…


AC Repair Service

From hassaninfo214 on October 19, 2018 :: 4:34 am

Nice Post.I have one window air conditioning in my room. Presently, its cooling is less. Things being what they are, I ought to revive it Thanks for sharing this information.


Window/Portable air conditioners

From Barbara J Ward on June 05, 2019 :: 12:53 pm

I’d love to see a post about hard to fit windows, small sized, casement, sliders and room cooling.


We have an article on that

From Josh Kirschner on June 05, 2019 :: 3:11 pm

We don’t cover all those hard to fit issues directly, but we have an article on our favorite portable air conditioners that can solve many of those issues.


Wall units?

From Josephine on June 05, 2019 :: 2:40 pm

I need a sleeve wall unit. Can you recommend one?


We don't have a specific recommendation

From Josh Kirschner on June 05, 2019 :: 3:23 pm

We don’t have a recommendation for a specific through-the-wall, unit. There are tons of choices out there, so I would focus on those models that have a large number of positive ratings and offer the features you’re looking or that fall within your budget. These models all get 4-stars and up on Home Depot and Amazon.


Cold outside now

From Fran Brown on October 15, 2019 :: 9:51 pm

My kitchen/living room are about 350 sq. ft. Remainder of home (2br, 1bath, hallway combined are about 400 sq.ft. Central heat and air. I have a window unit in the kitchen to help with the larger kitchen/living room area. Two questions (1) When the house is unoccupied, should I turn off the central and window unit-or leave them on, or use a timer? (2) should I close bedroom doors and close those vents when bedrooms are unoccupied?


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