Several window air conditioners in an apartment building facade.

Apartment living has its trade-offs. Sure, I never have to mow the lawn or shovel snow, but living in New York City, I also can’t just turn on the central air conditioning

In fact, my friends and I think of apartments with central air as unicorns—I’ve never actually been in one, or known anyone who has. We're faced with two options come summer: drown in our own sweat or install a window air conditioner.

MORE ON AIR CONDITIONERS

I’ve installed window air conditioners in a number of apartments, and let me just say, there’s definitely a learning curve. Below are answers to some key questions—like whether you need permission first and whether it’s okay to put one in the fire escape window—so you can avoid the mistakes I've made, no matter where you live.

Before you buy a window AC, make sure it’s the right size for your room. And check out CR’s air conditioner ratings and recommendations. Our air-conditioner tests show that performance varies quite a bit, so we can help you avoid a dud.

To jump to a specific question about installing a window air conditioner in an apartment, click on it here:

• Is one AC sufficient to cool a tiny apartment?

• Do you need permission to install a window AC?

• Do window ACs fit in any kind of window?

• Does the AC require its own designated electrical outlet?

• Can you install an AC in a window over a fire escape?

• Which window should the AC go in?

• How do you make sure the AC is securely installed?

• What if the AC falls out of the window? (Asking for a friend.)

• What should you do with the AC come winter?

• How do you properly dispose of an old AC?

Is One AC Sufficient to Cool a Tiny Apartment?

That depends on a lot of factors, like just how small are we talking about, and how many rooms are there? If it’s a studio apartment, one AC can easily get the job done. It gets trickier the more rooms and hallways you have. If you have ceiling fans, you can use them to help circulate the cool air (set them to rotate counterclockwise in summer, to force the air down and make you feel cooler). If the unit is in the main living area, placing a fan outside your bedroom door may also help direct cool air into it.

Generally, you can figure out how powerful an air conditioner you need by combining the square footage of each room, then looking for an air conditioner with enough Btu (British thermal units) to cool your space. Assuming you have the standard 8-foot ceilings, you need about 20 Btu for each square foot of living space—for example, 8,000 Btu can cool a space of 400 sq. ft. 

That's a pretty basic formula, though. You can customize the size you need by factoring in these aspects of your space, according to Energy Star:

  • If the room your AC is in is extra sunny, increase Btu by 10 percent.

  • If more than two people occupy your apartment, add 600 Btu for each additional person.

  • If the unit is used near the kitchen, add 4,000 Btu.

A window AC can reach upward of 30,000 Btu, but keep in mind that the physical size of the unit increases with cooling power, which means it may not fit in a standard window. Some larger models also won’t work on a standard 120-volt outlet (they require 230 volts).

Do You Need Permission to Install a Window AC?

A work permit isn’t usually required for installing a standard window AC unit, but you should still get permission from your building manager. “Most leases require that a tenant obtain prior landlord approval,” says Anna Liu, a real estate lawyer based in San Francisco. “Some even require professional installation.” Some supers will install it for you (mine charges $25 per unit), but some won’t touch it because of the liability. For more on that, see “What if the AC falls out of the window?” below.

Do Window ACs Fit in Any Kind of Window?

Windows can be weird, especially in a place like NYC, where a crack in the facade can be labeled a window. Because there is no standard window size, be sure to measure the height and width of the window opening to make sure your AC will fit.

Note: Most window ACs are made for double-hung windows—the kind that slide up and down to open. If you have a sliding or casement window, you may need a specially designed vertical window AC. Or opt for a portable air conditioner.

Does the AC Require Its Own Designated Electrical Outlet?

Some air conditioners can be electricity hogs and may need their own circuit—so don’t plug your hair dryer or toaster oven in an outlet on the same circuit, which may trip the breaker. Every apartment I’ve rented has had a designated outlet for a window AC, usually near the window sill. But a normal outlet works fine, too, as long as the cord can reach it. CR doesn’t recommend powering air conditioners via extension cords because that can be a fire hazard.

Can You Install an AC in a Window Over a Fire Escape?

A fire escape is exactly that: an escape route for fleeing or fighting a fire. So you don’t want to block it. Plus, it’s illegal. However, there is one exception. “You can put the AC in one window if you have another window that goes out onto the fire escape,” says Warren Kindler, director of the National Fire Escape Association. But that second window has to be large enough for a person to pass through (no, the little bathroom window doesn't count). And there still needs to be a 2-foot clearance on the fire escape walkway between the back of the AC and the railing.

Which Window Should the AC Go In?

“It's best to avoid placing an air conditioner in a window that gets a lot of direct sun,” says Chris Regan, CR’s resident air conditioner expert. “It’ll be forced to work harder.” Look for a window that's shaded by trees, an awning, or another building. Or opt for a north-facing window, which receives the least sunlight.

Also, check to see where your upstairs neighbors put their air conditioner and pick another window if you can. If their unit drains water, that constant drip, drip, drip onto your AC could drive even the mellowest people mad. But you do have one recourse if you have to install your AC right under your neighbor's: Place a sponge on top of the unit where the water drips to help buffer the noise. You won't see this tip in any books, my friends. It's from my own learned experience. And you're welcome.

How Do You Make Sure the AC Is Securely Installed?

I know it’s tempting to simply open the window, balance the AC on the sill, then close the window and hope for the best. But this method not only forces the window sash to bear all the weight of the air conditioner but also may tilt the unit and prevent it from draining properly. Worst-case scenario? It falls out (see below).

If your landlord allows it, get a support bracket. (Most of them mount to the outside wall directly under the window.) Once in place, you can rest your AC on the bracket while you install the AC. The alternative is precariously balancing the (heavy) AC on a high-floor window sill with one hand while shutting the window with the other—not an easy, or safe, task. The bracket also makes the AC more secure, period. Plus, it may be required by your landlord or local building code. 

CR doesn’t test AC brackets or recommend any specific models, but you can buy one for $30 to $100 (they don’t come with the unit).

What If the AC Falls Out of the Window? (Asking for a Friend.)

Didn’t I literally just tell you to use a bracket? 

Okay, what’s done is done. Hopefully, the AC didn’t hurt anyone or damage any property—that’s the best-case scenario (although, if a cop happened to witness it fall out your window, you can be fined by the city). If it did damage property or injure someone, “the landlord, tenant, installation company, and property manager could all be liable, depending on the manner in which the AC was installed and who installed it,” says Liu. Meaning, you can get sued. 

The best way to cover your butt is to have personal liability coverage in your renters insurance policy. Which means you need to get renters insurance. Opt for coverage that goes beyond simply protecting your belongings and add personal liability coverage, in case anything you own accidentally hurts someone or damages another person's property.  

What Should You Do With the AC Come Winter?

If you don’t have space in your apartment or building to store the AC, you can leave it in the window and protect it with a slip-on cover during winter months—some go on the part of the AC that’s outside the window to protect it from freezing rain and snow, and some slip over the part that’s inside your apartment to keep out chilly drafts. I find that those plastic shrink-wrap window insulation sheets work great to keep out the cold, too.

If you want to remove the air conditioner, reverse your installation steps and set the unit onto a thick towel or newspapers spread on the floor to collect any moisture still in the unit. Wipe it down with a damp cloth, put all the screws and brackets in a zip-top plastic bag and tape it to the unit, then store it in a dry spot. “Mold can grow inside the ducts where the cool air exits,” says Regan. “You should always check for visible mold on your window air conditioner at the start of each season. If you see any, there’s likely a lot more mold deep inside the unit.” If there is, you’ll either need to get it professionally cleaned or get a new one.

How Do You Properly Dispose of an Old AC?

You can’t just toss an air conditioner in a dumpster or leave it out with the rest of your trash to be picked up. You could be fined by the city, and it’s also bad for the environment. Air conditioners contain refrigerant gases (for cooling the air) that need to be removed following regulations from the Environmental Protection Agency. Your city's sanitation department can usually do this, so contact them to find out what to do.

Okay, that about covers it. All there is to do now is pray that there's not a brownout or blackout in your area during any heat waves.