how to choose window air conditioner

We’ve been putting it off because the temperatures haven’t really hit the 30s yet, but the time has come to start thinking about how you plan on staying cool this summer. If you want to keep a room or two chilly but don’t want to freak out when you see your energy bill, a window air conditioning unit is a great choice.

There are quite a few benefits to these self-contained units. They will cool off an entire room without taking up a lot of space, they’re much more efficient than the old ‘window shakers’ of the past, and many of them are Energy Star rated so you’ll know you’re still choosing an eco-friendly appliance. Plus, they’re easy to install and easy to use.

How to choose a window air conditioner

vertical air conditioner in window

There are a few things you should consider when choosing a window air conditioner. Start with the size of your room. If the square footage of your room is 300 square feet, you’ll have to choose a window air conditioner that’s at least 8000 BTUs.

New adjustments to BTU

BTUs or British Thermal Units is a term used to measure heat. The higher the BTU rating, the more efficient the cooling power. To avoid any confusion when shopping for an air conditioner, one thing you’ll want to keep in mind is that rating labels for portable air conditioners have recently changed. The US Federal Trade Commission (FTA) and the Department of Energy (DOE) have come up with a new label to describe how efficiently these units can cool your room.

The new DOE labeling takes into account the heat generated by the machine. That means the new ratings will lower the effective cooling power of portable air conditioners. For example, if a portable air conditioner you’re looking at is rated at 12,000 BTU, there will also be another label listed at 7,500 called Seasonally Affected Cooling Capacity (SACC). With the heat generated from the machine itself included, the new label reduces the cooling capacity by 4,500 BTU.

Because a window-mounted unit will sit on your window sill and is exposed to the outside, any heat generated from the window air conditioner itself will be kept outside, so the new labels don’t currently apply to window air conditioners. At this time you’ll only see BTU on product listings.

There is a post you can reference on how to properly size your air conditioner, but for quick reference, here’s a handy chart:

100 to 150 square feet 5,000 BTUs
150 to 250 square feet 6,000 BTUs
250 to 300 square feet 7,000 BTUs
300 to 350 square feet 8,000 BTUs
350 to 400 square feet 9,000 BTUs
400 to 450 square feet 10,000 BTUs
450 to 550 square feet 12,000 BTUs
550 to 700 square feet 14,000 BTUs
700 to 1,000 square feet 18,000 BTUs
1,000 to 1,200 square feet 21,000 BTUs


Besides the square footage of your room, you should also consider whether or not the room has high ceilings if it’s a kitchen you’re trying to cool, and whether your room is in direct sunlight or partial shade. All of these factors will affect how well your window air conditioner performs.

How to mount a window air conditioner

window air conditioner

If you’ve ever seen a window air conditioner hanging precariously from a window, you’ve probably ducked and run. All it would take is one good slam of an inside door and it could tumble to the ground.

Mount it in a window

Knowing how to install and hang a window air conditioner properly is the key to air conditioning success. To install a window air conditioner, you’ll need to mount it in a window. Double-hung windows will easily accommodate standard sizes like 12,000 BTU.

Vertical or horizontal?

You can also hang a window air conditioner unit in a vertical window, but you may have to pick up or create a custom enclosure to prevent the cool air from heading outside.

Make sure it’s level

The window air conditioner must sit level, with the warm air release facing to the outside and the cool air facing inside. If it’s not properly supported, it could easily crash to the ground, so be sure you install it according to the manufacturer’s directions.

Enjoy your new window air conditioner

vertical air conditioner

Once your air conditioner is installed, all you’ll have to do is kick back and enjoy the cool air. There’s nothing quite like knowing you’ll sleep like a baby during the hottest days of summer, all because you took the time to install a window air conditioner.

Check out a few of the great window air conditioning units that are ready to keep you cool, and if you’d like more information on air conditioners, take a look at the buying guide Air conditioning 101.

Don’t forget to take a peek at all of the fans, dehumidifiers, and air conditioners available right now on Best Buy.

Shelly Wutke
Editor TV & Home Theatre
I'm a Vancouver freelancer and tech enthusiast. When I'm not writing you'll find me on my farm with my alpacas, chickens, and honeybees. Visit my website Survivemag