Portable air conditioners are independent, movable units with exhaust hoses that are easy to install and vent out of a variety of window types. Window air conditioners are generally less expensive than portable air conditioners, but they are more difficult to install and only fit in standard-sized windows. Both unit types must be vented to the outside to function properly and are better as a supplemental cooling source, rather than a home's sole source of cooling.
Neither portable air conditioners nor window air conditioners are intended to cool entire homes or apartments. They are meant to be room air conditioners and are often used to help supplement central air conditioning.
Portable air conditioners are designed to be more flexible than window air conditioners, which can only be carefully installed in standard-sized windows. While portable air conditioners must still be vented to the outside, their exhaust hoses are bendable and extend somewhere between five to seven feet, meaning the unit can be moved as needed. This allows for more direct cooling in different parts of a home throughout a day. The downside to portable air conditioners is that many, though not all, models have no good mechanism with which to properly dehumidify a room, but instead function like regular dehumidifiers, collecting water in a dish that must occasionally be emptied.
Window air conditioners are designed to be compact, affordable, and relatively efficient; some also double as heaters for wintertime. They are able to dehumidify a room through their system, without the need of a tray to collect water. The downsides to window air conditioners are that they cannot be moved very easily and that if they are improperly installed they may not function correctly or may even prove dangerous (e.g., fall and hurt someone).
To learn more about the main differences between the two types of air conditioners, check out the video below.
Which Provides Better Cooling?
Whether a portable air conditioner or a window air conditioner will better cool a room depends on a lot of factors, such as how large the room is, what the room is used for, local climate, and the energy efficiency of the unit itself. Regardless of air conditioner type, one of the best ways to cool a room is to choose the right sized unit.
Window air conditioners are usually quite loud as they work and rumble against window sills. The noise levels of portable air conditioners vary, with some models being as quiet as a fan and others being as noisy, if not noisier, than a window air conditioner. If noise is a major concern for the room that the air conditioner will go in, a quiet portable air conditioner is almost certainly the better choice.
The larger and more powerful the air conditioner, the more it will cost upfront. A high upfront cost is worth it, though, if it means buying the right size air conditioner.
Portable air conditioners are usually around $100 more expensive than window air conditioners of the same cooling capacity. Also, because portable air conditioners are generally larger and start at a higher BTU/h, they will be more expensive than window units with a lower BTU/h.
Where to buy
Amazon.com usually has a large variety of air conditioners. The bestsellers list on Amazon can be quite useful:
Portable air conditioners are typically easier to install than window air conditioners, even with "easy install" kits that now ship with most good A/C units.
One possible issue for those installing a unit alone is weight. Even with casters (wheels), some portable air conditioners can be very bulky and heavy to move. Likewise, window air conditioners can weigh up to 100lbs (45kg), making lifting difficult for most.
Whether dealing with a portable air conditioner or a window unit, it is important to buy the correct size for the room the unit will be cooling. Too small, and the unit will be quiet, but run constantly in an attempt to cool a room that is too big. Too large of a unit, and the air conditioner will be noisy and shut down too soon for the dehumidifying process to begin, which will leave a room feeling humid.
When it comes to window units, the window the unit will go in should be carefully measured. While modern window air conditioners can be installed in a variety of window sizes, they are still mostly standard sizes; for oddly-shaped windows, a window air conditioner is unlikely to fit.
To choose the right size air conditioner, calculate the area of the room (how to find the area of a room) and select the right BTU/h accordingly. BTU stands for "British Thermal Unit" and is the standard unit of measurement for air conditioners. It is the amount of energy required to heat or cool one pound of water by one degree in Fahrenheit. The higher the BTU/h, the larger and more powerful the air conditioner will be.
|Area of Room in Sq. Ft.||Recommended Cooling Capacity in BTU/h|
|100 to 150||5,000|
|150 to 250||6,000|
|250 to 300||7,000|
|300 to 350||8,000|
|350 to 400||9,000|
|400 to 450||10,000|
|550 to 700||14,000|
|700 to 1,000||18,000|
|1,000 to 1,200||21,000|
Other factors can affect how well a room air conditioner functions. When choosing the BTU of an air conditioner, consider the following:
- Poorly insulated rooms do not hold in cool air. If the room being cooled is poorly insulated, a more powerful air conditioner may be required. Alternatively, seek out ways to better insulate the room.
- A room that is in direct sunlight will require a more powerful air conditioner to stay cool; consider increasing capacity by 10%. In contrast, if the room is heavily shaded, decreasing capacity by 10% is possible.
- If the air conditioner is going to be in a kitchen where lots of heat is generated, increase capacity by 4,000 BTUs.
- A room that regularly has lots of people in it may feel warmer than one that usually only has a single person or couple in it. Energy Star recommends adding another 600 BTU for every person that is regularly in the room with the air conditioner.
Portable air conditioners have a larger cooling capacity and start at around 10,000 BTU/h, while window air conditioners start around 5,000 BTU/h.
As both types of air conditioners extract hot air from a room, they need a place to send it. Ventilation to the outside is how air conditioners take hot air from an area and replace it with cool air.
Portable air conditioners vent to the outside by way of a flexible exhaust hose. Some portable units have two exhaust hoses, one for venting hot air out and one for taking air in from the outside. Exhaust hoses are easily installed in open windows with the help of a window installation kit. While venting out of a window is the easiest and most common method of ventilation, a portable air conditioner can also be vented through a ceiling, door, or wall. Although it is possible to extend the exhaust hose, it is not advisable because doing so may void the warranty or even overheat the unit.
Window air conditioners sit on window sills, with the front of the unit inside a room and the bulk of it outside the window. If they do not fit snugly in a window, there is a risk of leakage, either of the hot air the unit extracts or the cool air it produces.
Efficiency and Power Consumption
It is easier to find an energy-efficient window air conditioner than it is to find an energy-efficient portable air conditioner. In the U.S., there are no federal regulations to mandate the energy efficiency of portable air conditioners, and so no portable air conditioner is given Energy Star ratings. This does not mean portable air conditioners cannot be energy efficient or that other laws do not govern efficiency, only that defining and determining portable air conditioner efficiency, specifically, is slightly more difficult.
EER ratings can be used to determine efficiency in both types of room air conditioners. EER stands for "energy efficiency ratio" and is the ratio of an air conditioner's cooling capacity—its BTUs/h—to the amount of power it uses in watts. (BTUs / Watts = EER rating. So a 10,000BTU unit that uses 1,000 watts of power will receive an EER rating of 10.0.) Room air conditioners with a high EER rating are more efficient than those with a low rating.
National standards require all air conditioners—including portable units—to have an EER rating of 8.0 or greater. Units with an EER rating of 10.0 or above will be very efficient.
Air conditioner efficiency can be affected by other factors, such as nearby lamps or electronic devices that might lead the unit to believe a room is warmer than it actually is. In higher humidity, fan speeds should be set low to help remove moisture.
Replacing air filters regularly is also important for unit efficiency. Most filters need to be changed every three months.
Air conditioners are noisy—there's no way around that. Both portable and window air conditioners are equally noisy but noise levels vary by manufacturer and model. So look for the decibel rating (dB) of a unit before buying; the lower the dB level, the quieter the unit will be.
The pros of portable air conditioners are:
- portability: can be moved from one room to another very easily
- easier to install: there is some work involved in getting the exhaust hose properly venting outside the window but it's easier than installing a window AC unit.
- more venting options: special install kits are available for portable air conditioners to vent through a door or the ceiling
- no ugly protrusions from the window outside
The advantages of window air conditioners are:
- No clutter in the house
- Better energy efficiency
- Are there Energy Star qualified portable air conditioners? - Energy Star
- BTU and EER - HowStuffWorks
- Common Portable Air Conditioner Mistakes - Air & Water
- Common Questions About Window Air Conditioners - Overstock.com
- How to Vent Your Portable Air Conditioner - Air & Water
- Is central air conditioning more energy efficient than window units? - Slate
- Portable Air Conditioners (Video) - Home Depot on YouTube
- Properly Sized Room Air Conditioners - Energy Star
- Room Air Conditioners - U.S. Department of Energy
- Understanding Energy Efficiency Ratios - Air & Water
- What Does It Cost to Run a 5000 BTU Air Conditioner? - SF Gate
- Wikipedia: Air conditioning
- How to Install a Window Air Conditioner - Lowe's