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How to Choose the Best Window Air Conditioner

Marc McCollough

By Marc McCollough
Updated March 15, 2022

A window air conditioner (A/C) cools you off and helps you manage energy costs. We’ll share some useful tips on how to choose and install the best window air conditioner unit for your home.

A bright bedroom with a window air conditioner installed.

How Do Window A/C Units Work?

A window air conditioner, also known as an A/C, conveniently cools a single room. It can be an easy-to-install alternative to a central air conditioning system if you don’t need to cool the whole house.

Most window air conditioners have multiple operating modes. The cooling mode reduces the temperature and humidity of the room’s air and then recirculates it with a fan.

Some models allow you to select from several preset cooling levels to help you keep your room at a climate that’s right for you. Other models let you set a desired temperature for the unit to maintain. The air conditioner operates using a sensor, turning off when the air reaches the preset level. When the actual temperature rises above the specified setting, the unit starts cooling the air again.

The fan-only mode uses less energy because it doesn’t use A/C. Instead, the appliance circulates and filters the air in the room much like a fan would. Some window air conditioners even have a heating mode. As with the cooling function, you set the desired temperature, and the heating system cycles on and off to maintain it. Always refer to the air conditioner manufacturer’s instructions for safety, installation and operation information.

Proper Air Conditioner Sizing

It’s important to choose the right size window air conditioner for your room. An undersized unit may not be able to completely cool the room, while one that’s too large won't remove enough humidity, leaving the air feeling damp. Proper air conditioner sizing starts with determining the square footage of your room by multiplying your floor’s length by its width.

Next, compare your room size to the window air conditioner’s British thermal unit (BTU) rating. A BTU rating indicates the amount of heat an A/C can remove from a room. Look for a unit with a higher BTU rating to cool a larger room.
 

Here are some general guidelines for choosing the appropriate BTU for your room size:

  • 150 to 350 square feet: 5,000 to 8,000 BTU
  • 350 to 550 square feet: 8,000 to 12,000 BTU
  • 550 to 1,050 square feet: 12,000 to 18,500 BTU
  • 1,050 to 1,600 square feet: 18,500 to 25,000 BTU
     

For added efficiency, consider factors that may reduce or increase the cooling need, such as how much shade or sun your room receives. Keep in mind that as the BTU rating increases, so will the size and weight of the air conditioner. You also want to keep in mind the window air conditioner energy-efficiency ratio (EER) since choosing appliances with a higher EER rating is important to create an energy-efficient home.

Window Air Conditioner Features

A small white window air conditioner.

Once you’ve determined the best window air conditioner size for your needs, it’s time to think about what features you’d like in your unit. Here are some common window air conditioner features:

  • A programmable timer lets you set the unit to turn on and off at specific times, helping you reduce energy consumption.
  • Smart air conditioners can be controlled via your phone and connected app.
  • Mechanical controls allow you to manually adjust fan speed and cooling level with ease.
  • Electronic controls allow you to set a specific temperature for the air conditioner to maintain. There are window air conditioner models that can gradually ramp up their cooling. This keeps the temperature mild while reducing noise at night.
  • Electronic ionizers can remove impurities, like pollen, from the air.
  • Venting options let you choose between recirculating room air or drawing outside air into the room while exhausting room air to the outside. Air conditioners remove humidity from the air as they operate. Look for a dehumidification rating that removes pints of moisture per hour to prevent mold and odors.
  • A remote control enables you to adjust settings and turn the air conditioner on and off from across the room. Some remotes also function as portable temperature sensors to keep your room evenly cooled, activating the air conditioner when the air around the remote reaches a specified temperature.
  • Filter sensors let you know when the air filter needs cleaning for better air quality. Choose a model with a washable filter for easy cleaning.
  • Some models are fitted with an extra-long cord that’s useful when your chosen window isn’t close to a power outlet.

How to Install a Window Air Conditioner

The front of a programmable window air conditioner.

Most window air conditioners fit standard windows with glass that you can raise or lower. Measure the inside dimensions of the installation window carefully to make sure you select a conditioner that fits. Window air conditioners are heavy, so it’s important to have someone help you with the installation.

Before installing a window air conditioner, keep in mind:

  • Installing the air conditioner in a shaded window will help it operate more efficiently. Choose a north-facing window since it’ll be in the shade for most of the day. 
  • The window you select for installation needs a suitable power outlet nearby. The manufacturer may specify that you plug the device directly into the outlet with no extension cord. The outlet’s circuit must be able to handle the electrical load of the air conditioner. Models have particular plug shapes and power needs, meaning that some will require a modified outlet to handle the energy load. Make sure the air conditioner you select is compatible with your outlet by checking the product description carefully before purchase.
  • Contact a licensed electrician if you have any doubts or questions or to determine what parts or accessories you might need to finish the job.

Here are some ways to help your A/C cool your home:

  • Make sure air can flow freely around the entire air conditioner. Keep the unit clear of obstructions, such as bushes that could get caught inside of the A/C. Make sure indoor items, like window treatments and furniture, are clear of the unit.
  • Keep the cool air in the room by closing fireplace dampers and floor or wall registers. Consider closing your shades or blinds when it’s sunny outside as long as the airflow isn’t blocked.
  • Maintain correct insulation and weatherstripping throughout your home. Read our guide on How to Weatherstrip Your Windows for more information.
  • Accessories such as weatherstripping and foam side panels help you seal and insulate the area around the air conditioner.
  • Keep your energy usage in check by using appliances, like dishwashers and dryers, primarily during the cooler hours of the day.

Window Air Conditioner Maintenance

Regular air conditioner maintenance ensures that your new window unit will remain efficient for years to come. Always remember to unplug your air conditioner before performing maintenance.

You should regularly perform the following tasks:

  • Clean or replace the air filter as specified by the manufacturer. A clean air filter keeps your A/C efficient and reduces dust. Extend the life of an air conditioner filter by vacuuming or washing it with water and mild soap. Allow it to dry before reinstalling.
  • Wipe down the cabinet gently as needed, avoiding the control panel.
  • If necessary, prepare the unit for seasonal storage according to the manufacturer’s instructions.

 

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