Think of portable air conditioners as the cooling choice of last resort. They’re better than a fan but not much. That’s what Consumer Reports discovered in its tests of eight portable air conditioners that, despite their claims, barely got a room below sweltering let alone the 78 degrees that’s considered the upper threshold of indoor comfort. Portable air conditioners are intended for homes in which window configurations or building regulations prevent installation of window units. But getting one is a compromise you may not want to make because they’re typically bigger, noisier, more expensive, and use more energy. In fact, retailers report that many portable air conditioners are returned each season by dissatisfied customers. Unlike a window air conditioner, all the mechanical parts of a portable air conditioner are sitting in the room you’re trying to cool. This contributes to the noise and less-than-capable cooling, as the portable unit is using conditioned air from the room to cool the condenser and exhausts the hot air out an ungainly exhaust hose that resembles a dryer vent.

That creates negative pressure causing unconditioned warm air from surrounding rooms or outdoors to be drawn into the room you’re trying keep cool. And it’s debatable how portable they are, since once the hose is connected to the kit in the window, you won’t want to move the unit, especially since they typically weigh 50 to 80 pounds. While they do have wheels, portable air conditioners can be difficult to roll on carpets and over raised thresholds between rooms.  They also need their space—the hose is 5 to 7 feet long and the air conditioner must be positioned away from any walls or furniture that may block its airflow. In our tests, we measured how long it takes a portable air conditioner to lower the temperature in a room appropriate for its claimed size from 90 degrees to 75. But few made it to even 80 after 100 minutes. None made our list of recommended air conditioners but if you have no alternative, consider the Friedrich ZoneAir P12B, $600. While only fair at cooling, it was a champ in our tests simulating brownout conditions, as were 10 other models.

While we test portable air conditioners the same way we test window units, most manufacturers don’t. The Department of Energy is reviewing the current industry test for portable air conditioner capacity and efficiency. The current test doesn’t account for what is often significant leakage and transfer of hot air into the space being cooled. One alternative being investigated by the DOE is that the industry adopt the window air conditioner test for portables as well, because it more accurately measures actual cooling. This would make it easier for consumers to compare portable and window air conditioners. don’t assume that a portable air conditioner rated at 5,000 to 15,000 British Thermal Units will cool like similarly rated window models. If a portable is your only choiceAll portables come with a kit that you install in a window. Make sure all your connections are tight and seal any air gaps. Get a ceiling fan. Create a cool breeze by running a ceiling fan.Close the curtains and shades to keep the sun from overheating your room.

The best window A/Cs from our tests When buying a window air conditioner, make sure you get the right size air conditioner for your room. Too small and you’ll be uncomfortable, too big and your room will cool too quickly without removing enough moisture from the air, leaving you cold and clammy. fix window unit air conditionerHere’s the top performer for each size.coil in ac unit Small: GE AEM05LS, $210, a CR Best Buywindow unit with heat and ac Medium: LG LW8014ER, $240 Large: LG LW1214ER, $350 —Mary H.J. Farrell (@mhjfarrell on twitter)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. How air conditioners work. 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. 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. 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. To see how portable air conditioners are installed, watch this video. For window units, see this video instead. 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. Home Depot's BTU recommendations for portable and window air conditioners are slightly different from the U.S. government's Energy Star recommendations (found in the table below). 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. Other factors can affect how well a room air conditioner functions. When choosing the BTU of an air conditioner, consider the following: 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. 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.