Window vs Portable AC: Which One is Better?

What’s better, a window AC or a portable AC? They each have their pros and cons, but an affordable window air conditioner is hard to beat for cooling a room. On the other hand, a portable air conditioner is a little easier to move, and it can be installed up to 6 feet out into a room, better able to get cooled air to the further reaches of the area.

But we’re getting ahead of ourselves…

Window Air Conditioner vs Portable Air Conditioner

Approximately 118 million homes in the U.S. use air conditioning to help cool their living space. Of these, about 32 million use individual AC units; that is, air conditioners that are not part of a central AC system. The two basic types of individual AC units are window air conditioners and portable air conditioners.

If you don’t have central air and are considering purchasing a room air conditioner to cool and dehumidify the room you occupy the most during hot weather, this article may help you decide what is best for your situation.

We look at pros and cons of window air conditioners vs pros and cons of portable air conditioners, their differences, costs and much more. You’ll understand the window AC vs portable AC challenge as it relates to your needs.

Window Air Conditioners

Window air conditioners are self-contained units that are designed to sit on the sill of an open window. Any remaining space around the AC unit is sealed to keep out hot air, insects and dust. The vast majority of window AC’s will only fit in a single-hung or double-hung window that opens from the bottom up, though a few models designed to fit in a casement window can be found. Check out our Guide to Casement/Sliding Vertical Windows here.

About three-quarters of the unit will be outside the window and one-quarter of it will be inside the room. Larger window air conditioners  require some sort of shelf or special braces to support the part that is outside. These Top 15,000 BTU Window Air Conditioners are examples. Most window AC units operate on 115 volts and are plugged into a standard wall outlet. Some of the larger units can also function as heaters, and these usually require 230 volts and special wiring.

How a Window AC Works

Window air conditioners perform the two basic functions of any true air conditioning system; cooling and dehumidifying. Warm air from inside your living space is drawn into the unit, passes through an air filter and then over a component called an evaporator that is very cold. Moisture from that warm air condenses on the cold evaporator coils and drips into a pan on the bottom of the unit. Because of this, the window AC should be mounted with a very slight outward tilt so that water that has been removed from the air in your living space will run out a drain tube to the outside of the building.

Key Point – This is a huge way in which a window air conditioner is better than a portable AC – the condensed moisture immediately and completely leaves your home.

Having passed over the cold evaporator, the cooled air is now blown back into your room. Meanwhile, the heat from the warm room air has been transferred to condenser coils on the back of the unit and blown into the outside atmosphere. The overall result is that both heat and humidity have been removed from the room, giving you a much more comfortable space to live in. Window AC units are generally only designed to cool a single room or living space rather than the entire home, as does a central AC system. However, some of the largest units will do a fair job of cooling a small apartment with a fairly open floor plan.

Advanced Window AC Features

Modern window air conditioners have many functions that were not found on older models. Some have programmable thermostats, humidistats and timers, LED readouts, remote controls, Wi-Fi and Bluetooth compatibility as well as being able to connect to smart technology devices.

Their modes include AC/Cool, Dehumidify (dry but not cool the air – ideal for cool, clammy days), and Fan Only that simply moves the air.

Key Point 2 – If you don’t have central air conditioning, a window air conditioner is the most efficient way to cool and dehumidify your living space – and they don’t take up any floor space.

Portable Air Conditioners

Portable air conditioners are relatively compact air cooling systems that are free-standing and are completely inside your living space while operating. Because of this, they are usually quite stylish and are available in several colors and finishes to blend in with the interior of your home. They cannot sit against a wall, and should have at least 20 inches of clear space on all sides.

Key Point – Portable ACs perform the same basic functions of cooling and dehumidifying the air inside your home as a window air conditioner, but at a reduced level.

Because of their design, they are only marginal in dehumidifying when the humidity level in your room is above 70%. In some areas of the U.S. this is the case much of the summer cooling season; in the western regions it is not. Some models have a water tank to collect the moisture that must be emptied regularly. Others claim to send most of the moisture out with the hot air, but this is usually qualified to only apply in low humidity environments.

Most portable air conditioners will only effectively cool one room or a very small open-design apartment. Many of the larger models have wheels to make them easier to move from one place or room to another. Some models also have the ability to function as a room heater instead of an air conditioner.

Two Portable Air Conditioner Designs: Single Hose and Dual Hose Units.

There are important distinctions between the designs that affect their performance and ability to cool and dehumidify the space.

1. Single Hose Portable Air Conditioners

Single hose portable AC units pull air from within the room (usually from the back) and blow cooled air out the front. They then expel some hot air produced by the air conditioning process and some moisture from the room air through a single hose that is connected to a special “window kit” that is usually provided. These units have a water tank to collect much of the moisture removed from the air. The tank must be emptied on a regular basis, or connected to a floor drain through a tube or hose.

Dual hose portable ac1

Portable AC’s Pull in Warm, Humid Air – a Disadvantage

A downside of this type of air conditioner is that they create “negative air pressure” in the room because while they are operating, air is constantly being pushed out of the room through the hose connected to the window kit. As a result, the air in the room has to be replaced with air from somewhere else.

Air leaving the house must be replaced: To understand this better, think of what happens when you drink a beverage out of a full container (cup, carton, bottle, whatever) through a straw. In this analogy, the container is your room, the liquid is the air in your room, the straw is the exhaust hose on the portable AC unit, and your mouth is the air outside your home. When you draw the liquid out of the container through the straw into your mouth, what happens? Air from outside the container is drawn in to take the place of the liquid that has been removed.

In the same way, when a single hose portable air conditioner takes air from your room and blows some of it out of your room into the outside air, it creates a negative (lower pressure) atmosphere in the room which causes other warm air to come in. This might come through cracks under the door, around the windows, through the wall outlets or wherever it can. And about that hose – it gets hot and it radiates heat. And since it’s inside your room, it only adds to the problem of trying to cool the room.

Key Point – Portable air conditioners with one hose are about half as efficient: The net effect of all this is that it also makes the single hose portable AC unit much less efficient than a window air conditioner. This will be noted on the rating sticker that will be found on the box that the unit is packaged in. By law, there will be a BTU rating by ASHRAE (American Society of Heating, Refrigerating and Air-Conditioning Engineers) and another BTU rating by the DOE (Department of Energy).

Don’t believe the ASHRAE Rating: To state it simply, the ASHRAE rating does not figure in the negative effects that are inherent in the design of portable air conditioners when operating inside your room. The DOE rating does. What this means is that the actual, or “effective” amount of cooling is truly seen in the DOE number. It’s usually anywhere from 25-50% less than the ASHRAE rating. This is the number you should look at if you are considering any portable air conditioner.

2. Dual Hose Portable Air Conditioners

There’s good news and bad when considering a dual hose portable AC.

The Good News

Higher efficiency and moisture control: Dual hose portable air conditioners are more energy efficient and therefore cool a room more quickly than their single hose counterparts. They also will dehumidify, and are much better at removing the moisture from the room than single hose units. In very humid environments, excess water will be diverted to a holding tank. This will vary greatly from one brand and model to another. Some models also have the capability of having a drain tube connected to the tank to drain continuously.

How the Two Hose Design Works

Dual hose portable ac2

The dual hose design has two separate hoses that are connected to a window kit to the outside of the building. One hose (intake) will draw air in from the outside, and a second one (exhaust) will blow air back outside. The room air is drawn into the AC unit where it is cooled inside the unit and then blown back into the room. The process of cooling this air generates heat inside the unit, just as it does in all air conditioners. So the outside air comes through the intake hose to cool the unit’s compressor and condenser coils – which are very hot - then is blown out the exhaust hose.

The Plus Side of Dual Hoses

The advantages of the dual house design are in its ability to cool an area more efficiently and quickly than a single hose unit, while requiring less work for the portable air conditioner. Dual hose units can cool a room 40-50% faster than a single hose unit, which results in a higher efficiency rating.

The Bad News

In spite of their better performance, there are relatively few dual hose portable air conditioners on the market. The majority of those that are available are quality units with good to excellent customer reviews.

Key point – They’re better than single-hose, but not as good as a window air conditioner. Even though the dual hose portable air conditioner is producing more net cool air than a single hose unit of equal size, the actual cooling effect (DOE rating) is still lower than the listed ASHRAE rating. This is because (a) the hot components of the unit are inside the room, and (b) both the intake - and especially the exhaust - hoses are also inside the room. This results in a lot of heat radiated inside the very space that the portable air conditioner is expected to cool. So while they beat their single hose counterparts, they still do not equal the cooling and dehumidifying efficiency of a window air conditioner.

Sizes and Costs

Both window air conditioners and portable air conditioners are available in a variety of different sizes with the ability to provide cooling for a wide range of living spaces. Prices will vary depending on type, brand, size, additional features and where you purchase the product. Here is a chart giving some sample information on units that are available. Some of these units can be found in big box stores or appliance stores, but others can only be found online.

AC Type

Sq. Ft. Rating

BTU Rating

With Heat

Ave. Price

Window






150

5,000


$170.00


250

6,000


$250.00


350

8,000

X

$480.00


550

12,000


$440.00


1,000

18,000


$550.00


1,600

25,000

X

$990.00

Portable 1 Hose






300

8,000 / 6,000


$385.00


550

12,000 / 6,000

X

$390.00


525

14,000 / 8,600

X

$620.00

Portable 2 Hose






425

12,000 / 5,400


$590.00


500

12,000 / 6,500


$610.00


500

14,000 / 9,500

X

$670.00

What About “Ventless” Portable AC Units?

The ventless portable air conditioner is a bit of a misnomer because it isn’t really an air conditioner. They are often sold as such, but they do not operate in the manner of a true air conditioner.

They are properly called “evaporative coolers”, but they are also called, “swamp coolers”. They are not rated by BTU’s, which is a measure of cooling, but simply rated by the amount of air their fan will move through the room. This rating is called, “CFM” which stands for Cubic Feet per Minute.

How They Work

They provide some cooling effect to your living space by drawing the warm room air in and circulating it over water-soaked pads or other types of absorbent material. This water is pumped from a self-contained reservoir which must be refilled every 1-3 days, depending on its size. An exception to this is the very large evaporative cooler that is designed for large, open buildings – like repair garages and warehouses. These will be connected to a permanent water supply. But whatever the size, the principle is the same. The air moving over the wet material evaporates some of the moisture on the pads which causes the air blown back into the room to feel somewhat cooler than before. The residential portable evaporative cooler operates on standard 115 volts.

The major drawback of evaporative coolers is that they provide a cooling effect only when the moving air passes directly over the skin of the occupants of the room. But by raising the humidity level of the space in which they are operating, they also reduce the ability of moisture to evaporate naturally on our skin, which is what helps us feel cooler.

Consider one If you live in a very dry climate. One of these coolers may help by adding some humidity to the room, making it more comfortable. But wherever summer humidity levels regularly reach 60% or higher, you will probably not appreciate the effects produced by these units.

Key Point – Manufacturers of this type of evaporative cooler only recommend them for use in the western half of the U.S. where the weather is generally hot and dry. For the rest of the country, they recommend a true air conditioner. As for sizes and costs, they cover a very wide range. Starting at less than $100.00, you can get a desktop model that only moves 47 CFM (Cubic Feet per Minute). Some large warehouses and other open floorplan buildings might use the model that moves 8,000 CFM and costs almost $2,000. The average room-sized unit moves between 200-500 CFM and the cost ranges anywhere from $150.00 to $500.00.

Conclusion

With the exception of the coldest parts of the country, there are probably summer days when your home is uncomfortably warm.

Most of you will benefit more from a window AC than a portable AC. Window units are:

  • More energy efficient
  • Remove more humidity
  • Come in a wider range of sizes, starting with smaller window ACs perfect for small bedrooms and offices and larger units too to deliver the right cooling and dehumidifying to match your square footage

Fortunately, there is a wide variety of options for you to improve the comfort of your living space if you do not have central air conditioning. Whether you choose a window air conditioner or a portable air conditioner, do your homework, read ratings and customer reviews, and choose the type and size of unit that is right for your situation and climate.

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