Portable air conditioners work a lot like any other kind of air conditioner, whether a window unit or a central air conditioning system. Chemical refrigerant flows through a series of coiled tubes and absorbs the heat from indoors. The heat is then released outside through an exhaust hose. The main difference is that with window AC, the heat is released by the portion of the unit that hangs out of the window. For portable units, warm air is guided outdoors through a single or dual hose that looks like a flexible dryer vent. A portable AC unit will typically come with a single hose and a window kit that allows you to set up the venting system quickly and easily.

It’s a bit of a misconception that portable air conditioning systems can be moved into different rooms on a whim. Because of the need to exhaust air through a window, moving a unit around will require also moving its exhaust vent. This is simpler with a window kit, but many people will not find it as convenient as carrying a space heater from room to room.

It’s no secret that cool air isn’t cheap. Air conditioners use a lot of electricity to keep your home cool, and that’s true regardless of what kind you use. Your total cost will be based largely on how often your portable or window air conditioner cycles on — and how long it stays on. This will depend on several factors:

NewAir Portable Air Conditioner 14,000 BTUs. Photo taken by @thatstrangebunch

The hotter it is outside, the more hot air you’ll have to remove from your house. It doesn’t take as much energy to cool a room to 72 degrees on a 77-degree day as it does to get cool on a 95-degree day. You can mitigate how much you spend by turning your thermostat up on the hottest days. You’ll still feel cooler inside than you would outdoors, but your portable air conditioning or window AC unit won’t have to work so hard. You can also help your air conditioner do its job by making sure your space is well insulated and by closing blinds and curtains to block out bright sunshine.

For your air conditioning to have enough cooling power to actually make your rooms noticeably more comfortable, it needs to be sized properly. One window air conditioner, for example, will never provide enough cooling for an entire house. An undersized air conditioner will run all the time, cost you big bucks and still not make you happy.

To make sure your portable air conditioner is sized properly for the room you plan to cool, you need to look at its BTU rating, which measures the unit’s cooling power. For smaller rooms of 200 square feet, a unit with 8,000 BTUs should suffice. For a large living room of 600 sq. ft., look for a portable air conditioner with 14,000 BTUs.

If you’re trying to cool a kitchen, you should size up when it comes to cooling power. All those appliances create a lot of extra heat, which will make your unit work even harder to get the job done.

How much you spend to run your portable air conditioner will vary greatly based on the price of electricity in your area. These costs tend to rise with demand during the hottest summer months, so getting cool during a freak heat wave in May probably won’t cost you as much as seeking relief in August. If you’re subject to prices that fluctuate during peak periods, it may even be cheaper to run your portable AC at night than it is during the day. This is all to say that your mileage may vary as to whether you find the cost of running a portable air conditioner to be a reasonable concession on a hot day or if you’d prefer to stick things out with a fan or an evaporative cooler instead.

• It gives you access to your windows.For apartments with only a few windows, blocking the only source of natural light with a chunky window unit could be a non-starter. Portable air conditioners also allow you some flexibility about where you place the unit to work with the traffic flow in your room. Window units, not so much.
• It’s ready to use right out of the box.You don’t need any help installing a portable air conditioner — or a friend to help you lift it into place in your window. You won’t even need any tools if you get a handy window kit to fit the exhaust hose in place with your window a few inches ajar. All you have to do is plug it in to beat the heat.

• It’s generally less efficient. Portable air conditioners often take more BTUs — and therefore use more electricity — to cool the same square foot space as a window unit. This is likely because they generate waste heat indoors instead of outside, creating more overall heat for the unit to deal with. For example, a 10,000 BTU window unit will cool 450 square feet, but a 10,000 BTU portable AC unit will cool only 300 square feet.
• It could get loud. Portable air conditioners have all their working parts right inside the same room where you may want to eat or watch TV, so the noise level may be disruptive. You can adjust settings to slow down the fan speed to help with this, or you could roll the unit to a farther corner if your exhaust hose is long enough.

NewAir Portable Air Conditioner 14,000 BTUs. Photo taken by @annawho13

Portable air conditioners can be remarkably convenient for many homeowners and renters, and they are an affordable way to bring a little cool air into your living space. They can also be a lifesaver if your regular air conditioner is broken — you can get them up and running quickly while you wait for repairs. If you decide to give portable air conditioning a try, be sure to measure your room so that you purchase a unit that is sized properly for the space, and you’re likely to enjoy a comfortable home all summer long.