Portable Vs. Window AC Units: Pros, Cons, & Costs

When you live in a small space such as a studio apartment or a single-floor home, you probably don’t need all the power of a central air conditioning system to cool your indoor air. Smaller, more affordable types of air conditioners can typically provide all the cold air you need to stay comfortable. As long as you pick the right one for your home, that is.

Small homeowners and people who rent apartments often use portable air conditioners or window-mounted units to cool their living spaces. While there are some similarities between these two types of AC units, important differences could make either one better for your situation.

In general, the higher efficiency, greater affordability, and lower decibel levels of window-mounted units make them better for most people. That said, portable units aren’t without their charms (namely convenience).

Keep reading, and we’ll compare the virtues and drawbacks of both types of HVAC units to help you decide which is better for your situation.

Quick comparison

Pros and cons of window air conditioners

As you might guess, window air conditioning units are designed to sit between window sills and open window sashes. Image source: Home Depot

As their name suggests, window AC units are installed directly into windows, and depending on size, they can take up most of a window’s frame. Inside a window AC unit sits many of the same components you’ll find in a central AC system, including a compressor, an evaporator, condenser coils, and a fan. 

A window air conditioner works to cool your space in two ways. First, it pumps fresh air from outside the home through the condenser, cools the air with refrigerant, dehumidifies and filters it, and then blows the cool air into the living space. While this happens, the unit also sends hot air inside the living space outdoors.

Window air conditioners come in various sizes and output levels, and high-end options can sometimes exceed 20,000 British thermal units (BTUs) of cooling power. For reference, this is usually enough power to cool a space that measures 1,000 square feet. Since the Department of Energy holds window ACs to high-efficiency standards, they’re also relatively cheap and environmentally friendly to operate. 

Window units also run with relatively little noise. Most of their loudest components, like fan motors and condensers, are located in their back halves. Since the back half of a window AC sits outside a window when installed, most of the noise these units make during operation can’t be heard indoors.

The main downside is that window units are fairly cumbersome and hard to install. DIY installation is sometimes possible as long as you follow your unit’s installation instructions to the letter. For large and heavy units, hiring a pro for installation is the best way to ensure your unit is securely fixed and won’t fall out. 

Similarly, while some window units can just plug directly into a standard home’s power outlet, some powerful window units require dedicated, high-voltage circuits. If you get one of these high-output units, you’ll also need to have a circuit installed by an electrician.

In short, window units are powerful, efficient, and whisper-quiet but aren’t the most convenient way to beat the heat. 

Pros and cons of portable air conditioners

Most portable AC units are meant to sit on the floor beside a window. They typically feature exhaust hoses to pump hot air outside. Image source: Home Depot

The main benefit of a portable AC unit is convenience. Portable units don’t get installed in window frames. They stand upright on the floor, usually on wheels. This design is more convenient for two main reasons. 

Firstly, it means portable units don’t have much of an installation process. You simply unpackage your unit, plug it in, funnel its exhaust hose (and return hose if you get a dual-hose model) through a window, and set the thermostat to your taste. Just like that, the unit is ready to cool your air. Secondly, because these AC units usually feature wheels, they can easily be rolled from room to room for targeted cooling. 

Portable ACs feature many of the same mechanical components as a window unit and work similarly. The main functional difference is that a single-hose portable AC draws in and cools inside room air instead of sourcing new air from outside. It then expels hot air into the great outdoors using its exhaust hose. Dual-hose models operate slightly more like window units, bringing in new air to cool from outside using return hoses. 

Unfortunately, portable units fall short of window ACs by most metrics. They tend to cost a little more, they usually aren’t as powerful (the output of portable units tops out at about 16,000 BTU), and because every component of a portable unit sits inside the home that it’s cooling, they’re much louder. While portable units have their own efficiency standards, they tend to be less energy efficient than window units and can cost a bit more to operate.

Another drawback is that the low output power of a portable unit means you’d only really want to use it for cooling a small room, but it will take up valuable floor space in that room. This alone makes the portable design less than ideal.

All told, portable ACs are only better than window-mounted models for two kinds of people:

• Those whose landlords or HOAs won’t allow them to install window units
• Those who want to supplement another AC’s cooling power

Other factors to consider

What if you don’t have windows?

Since both portable and window-mounted AC units require window access, neither of them can be used to cool a windowless space. If the living space you need to condition has no windows, then a ductless mini-split AC is probably your best option. 

A mini-split system uses indoor air for cooling. It chills the air, dehumidifies it, filters it, and pumps it into the living space over and over again. This system allows this type of system to cool a space without access to fresh air, though they require outdoor condenser units.

The main downside of this type of system is cost. You’ll likely need a multi-zoned mini-split with multiple cooling units if you have a large space with several rooms. Depending on how large your space is, getting an adequately powerful mini-split system can cost thousands of dollars. 

How to choose your unit

The most important factor in choosing an air conditioner is power output. If you get a system that isn’t powerful enough to cool your space, it will work overtime and still produce subpar results. Alternatively, if you get a system that’s too powerful, it will cool your home just fine, but it won’t operate as efficiently since it will use a lot of unnecessary power.

It’s all about finding the sweet spot. In general, the Department of Energy recommends purchasing a system with at least 20 BTUs of cooling power for every square foot in your living space. 

For example, if you live in a 500-square-foot apartment, you’ll need a 10,000 BTU system. If you live in a 1,200-square-foot space, your system must have 24,000 BTUs of cooling power. Use this formula to find an AC unit with enough output for your space. 

Keep your filters clean

Both window-mounted and portable AC units have air filters that you must routinely clean or replace. In general, you should check your ACs filter every month or two and replace it if it’s noticeably full of dust, pet hair, or pollen. Failing to keep your unit’s air filters clean can reduce its efficiency and cause it to malfunction before its time. 

Filter placement can vary by model, so refer to your operator’s manual to find your unit’s filter. 

Should you get a portable AC or a window-mounted unit?

In most cases, window AC units are a better choice than portable units if you want to conserve space, make your home more efficient, and save money. However, if you need to get some cool air flowing quickly and your landlord won’t let you install a window unit, a portable unit might work better for your situation.