Are Portable Air Conditioners a Lot of Hot Air?

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 portable air conditioners: Despite their claims, these machines barely got a room below sweltering, let alone the 78° F that’s widely 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.
“A portable air conditioner is an alternative—but not an ideal one,” says Chris Regan, who oversees Consumer Reports’ air-conditioner tests. Portable units are typically bigger, noisier, and more expensive, and use more energy. In fact, retailers report that many portable air conditioners are returned each season by dissatisfied customers.
How Portable Air Conditioners Work
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. It’s also a reason for the less-than-capable cooling: The portable unit uses 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.
How Portable?
And it’s debatable how portable they are because once the hose is connected to the kit in the window, you won’t want to move the unit, which typically weighs 50 to 80 pounds—sometimes even more.
How We Test Portable AC
In our tests, we measure how long it takes a portable air conditioner to lower the temperature from 90° F to 75° F in a room appropriate for its claimed size. But few make it even 80° F after 100 minutes. None makes our list of recommended air conditioners. But if you have no alternative, consider the Friedrich ZoneAir P12B, $580. While the unit earned only a Fair rating for cooling, it was a champ in our tests simulating brownout conditions, as were most of the other models.
If a Portable Is Your Only Choice
Install it right. All 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 fan. Create a cool breeze by running a ceiling fan or using a box fan.
Block the sun. Close the curtains and shades to keep the sun from overheating your room during the day.

Best Window Air Conditioners for the Hot Days Ahead

All of the window air conditioners in Consumer Reports’ latest tests do a good enough job at keeping you cool. What distinguishes one window unit from another is how quickly and quietly it cools a room—and how easy it is to operate.
Even if your home has central air conditioning, you might want to consider a room unit to cool areas not served by the main system, such as a home office or a finished room in the attic. If you do, go with a window air conditioner. They’re a better choice than portable air conditioners, which struggle in our tests.
And you don’t have to pay a lot to get heat relief. Most window air conditioners in our tests range from $150 to $400. The outlier? The Friedrich Kuhl SQO8N10D, $710, a strong performer with a streamlined look.
To help a window unit run more efficiently, look for a model equipped with insulating panels. “Most new window ACs come with panels you place over the plastic adjustable side panels to boost efficiency,” says Chris Regan, CR’s senior test engineer for air conditioners. Adding weatherstripping around the perimeter will also prevent air from leaking in or out.
How We Test Window ACs
After installing the unit in a double-hung window in our testing chamber, we crank up the chamber’s heat to 90° F, then measure how long it takes the AC to cool the room by 10° F (the best units do it in less than 15 minutes). We also gauge how accurately the AC reaches the set temperature, whether each model can recover after a brownout, how intuitive the controls are, and how loud each unit is on the lowest and highest settings.
Below, grouped alphabetically by the size room they can cool, are some of CR’s top-performing window air conditioners. For more on getting the best fit, find out how to size a window air conditioner. You’ll find even more choices and a broader price range in our full air conditioner ratings and recommendations.

Amana AMAP061BW

CR’s take: The Amana AMAP061BW, a newcomer to our test labs, turns out to be a cool addition. It capably cools the test chamber and is a champ at recovering from brownout conditions when the voltage is low, earning an Excellent rating on that test. It comes equipped with a remote control, built-in timer, and dirty-filter indicator. But it’s a bit noisy on both low and high settings.

GE AHM05LW

CR’s take: A CR Best Buy, the GE AHM05LW earns a Very Good rating for comfort but, like the Amana, can be a bit noisy at any speed. It quickly recovers from brownout conditions and has a full suite of features, including a remote, built-in timer, and dirty-filter indicator.
Friedrich Kuhl SQO8N10D

CR’s take: The Friedrich Kuhl SQO8N10D makes an effort to blend in with your décor with a flat front instead of a grille. It aces the cooling test, earning an Excellent rating in that test, and runs quietly on low speeds, although gets a tad noisier on high. Controls are a cinch to use, and it’s equipped with all the conveniences of a timer, remote, and more. This 85-pound model comes with a slide-out chassis that makes it easier to install.
Kenmore 77080

CR’s take: With an Excellent rating for cooling—and intuitive controls—the Kenmore 77080 is a good bet for a midsized room. It’s pretty quiet on the lowest setting, but you’ll hear it running when you crank it up to high. At 52 pounds it weighs considerably less than the Friedrich above. It comes with a remote, built-in timer, and dirty-filter indicator.
LG LW1216ER

CR’s take: A CR Best Buy, the large, feature-filled LG LW1216ER has digital controls, and cooling is top-notch. It weighs 85 pounds, but its slide-out chassis makes it easy to install. It has all the convenience features—remote control, built-in timer, and dirty-filter indicator. It’s a good choice for a large living area and earns a Very Good rating for noise on low, which means it won’t annoy you if you’re watching TV.
SPT  WA-12FMS1

CR’s take: Another candidate for large spaces, the SPT WA-12FMS1 is top-notch at cooling, although it’s noisier than the LG at both low and high speeds. On the plus side, our testers found the controls were more intuitive; it earns a Very Good rating for ease of use. It also comes with a full range of features, including a remote, timer, and dirty-filter indicator.

How to Size a Window Air Conditioner

Size matters when you’re buying a window air conditioner. An AC that’s too small will struggle to keep the room at a comfortable temperature; a model that’s too big will cool the room too quickly without removing enough humidity from the air.
Choose just right and you’ll feel just right—and save money, too. Consumer Reports tests air conditioners in rooms that are the same size as the ones they’re intended to cool. That makes it easier for you to select the best model for your needs.
How we test window ACs. After installing a window air conditioner in a double-hung window in our lab, we crank the heat up to 90° F in the surrounding area and measure how long it takes the AC to cool the room by 10° F.
“The best models in our tests can cool the room in less than 15 minutes,” says Chris Regan, the engineer who oversees CR’s air-conditioner tests.
We also gauge how accurately the AC reaches the set temperature, whether each model can recover after a brownout, how intuitive the controls are, and how loud each unit is on its lowest and highest setting.

The Rules for Keeping Cool
Window air conditioners typically have a cooling capacity ranging from 5,000 to 12,500 British thermal units (Btu/hr.). As a rule of thumb, an air conditioner needs 20 Btu for each square foot of living space.
But don’t buy by Btu alone. Other considerations, such as the ceiling height and the size of your windows and doorways, might call for for more cooling power.
To measure your room, multiply the length of the room by the width. Add together the size of rooms that aren’t separated by doors because the air conditioner will need to cool both spaces. Energy Star recommends that you make adjustments for the following circumstances:
• If the room is heavily shaded, reduce capacity by 10 percent.
• If the room is very sunny, increase capacity by 10 percent.
• If more than two people regularly occupy the room, add 600 Btu for each additional person.
• If the unit is used in a kitchen, increase capacity by 4,000 Btu.

What is Air quality?

An air quality index (AQI) is a number used by government agencies  to communicate to the public how polluted the air currently is or how polluted it is forecast to become. As the AQI increases, an increasingly large percentage of the population is likely to experience increasingly severe adverse health effects. Different countries have their own air quality indices, corresponding to different national air quality standards. Some of these are the Air Quality Health Index (Canada), the Air Pollution Index (Malaysia), and the Pollutant Standards Index (Singapore). Definition and usage
An air quality measurement station in Edinburgh, Scotland
Computation of the AQI requires an air pollutant concentration over a specified averaging period, obtained from an air monitor or model. Taken together, concentration and time represent the dose of the air pollutant. Health effects corresponding to a given dose are established by epidemiological research.[4] Air pollutants vary in potency, and the function used to convert from air pollutant concentration to AQI varies by pollutant. Its air quality index values are typically grouped into ranges. Each range is assigned a descriptor, a color code, and a standardized public health advisory.
The AQI can increase due to an increase of air emissions (for example, during rush hour traffic or when there is an upwind forest fire) or from a lack of dilution of air pollutants. Stagnant air, often caused by an anticyclone, temperature inversion, or low wind speeds lets air pollution remain in a local area, leading to high concentrations of pollutants, chemical reactions between air contaminants and hazy conditions.
Signboard in Gulfton, Houston indicating an ozone watch
On a day when the AQI is predicted to be elevated due to fine particle pollution, an agency or public health organization might:
advise sensitive groups, such as the elderly, children, and those with respiratory or cardiovascular problems to avoid outdoor exertion.
declare an “action day” to encourage voluntary measures to reduce air emissions, such as using public transportation.
recommend the use of masks to keep fine particles from entering the lungs
During a period of very poor air quality, such as an air pollution episode, when the AQI indicates that acute exposure may cause significant harm to the public health, agencies may invoke emergency plans that allow them to order major emitters (such as coal burning industries) to curtail emissions until the hazardous conditions abate.
Most air contaminants do not have an associated AQI. Many countries monitor ground-level ozone, particulates, sulfur dioxide, carbon monoxide, and nitrogen dioxide, and calculate air quality indices for these pollutants.
The definition of the AQI in a particular nation reflects the discourse surrounding the development of national air quality standards in that nation. A website allowing government agencies anywhere in the world to submit their real-time air monitoring data for display using a common definition of the air quality index has recently become available.
Indices by location
Canada
Main article: Air Quality Health Index (Canada)
Air quality in Canada has been reported for many years with provincial Air Quality Indices (AQIs). Significantly, AQI values reflect air quality management objectives, which are based on the lowest achievable emissions rate, and not exclusively concern for human health. The Air Quality Health Index or (AQHI) is a scale designed to help understand the impact of air quality on health. It is a health protection tool used to make decisions to reduce short-term exposure to air pollution by adjusting activity levels during increased levels of air pollution. The Air Quality Health Index also provides advice on how to improve air quality by proposing behavioral change to reduce the environmental footprint. This index pays particular attention to people who are sensitive to air pollution. It provides them with advice on how to protect their health during air quality levels associated with low, moderate, high and very high health risks.
The Air Quality Health Index provides a number from 1 to 10+ to indicate the level of health risk associated with local air quality. On occasion, when the amount of air pollution is abnormally high, the number may exceed 10. The AQHI provides a local air quality current value as well as a local air quality maximums forecast for today, tonight, and tomorrow, and provides associated health advice.

12345678910+
Risk:Low (1–3)Moderate (4–6)High (7–10)Very high (above 10)
Health RiskAir Quality Health IndexHealth Messages
At Risk population*General Population
Low1–3Enjoy your usual outdoor activities.Ideal air quality for outdoor activities
Moderate4–6Consider reducing or rescheduling strenuous activities outdoors if you are experiencing symptoms.No need to modify your usual outdoor activities unless you experience symptoms such as coughing and throat irritation.
High7–10Reduce or reschedule strenuous activities outdoors. Children and the elderly should also take it easy.Consider reducing or rescheduling strenuous activities outdoors if you experience symptoms such as coughing and throat irritation.
Very highAbove 10Avoid strenuous activities outdoors. Children and the elderly should also avoid outdoor physical exertion.Reduce or reschedule strenuous activities outdoors, especially if you experience symptoms such as coughing and throat irritation.

The AQI is based on the five “criteria” pollutants regulated under the Clean Air Act: ground-level ozone, particulate matter, carbon monoxide, sulfur dioxide, and nitrogen dioxide. The EPA has established National Ambient Air Quality Standards (NAAQS) for each of these pollutants in order to protect public health. An AQI value of 100 generally corresponds to the level of the NAAQS for the pollutant.[10] The Clean Air Act (USA) (1990) requires EPA to review its National Ambient Air Quality Standards every five years to reflect evolving health effects information. The Air Quality Index is adjusted periodically to reflect these changes.
Computing the AQI
The air quality index is a piecewise linear function of the pollutant concentration. At the boundary between AQI categories, there is a discontinuous jump of one AQI unit. To convert from concentration to AQI this equation is used:[35]
If multiple pollutants are measured at a monitoring site, then the largest or “dominant” AQI value is reported for the location. The ozone AQI between 100 and 300 is computed by selecting the larger of the AQI calculated with a 1-hour ozone value and the AQI computed with the 8-hour ozone value.
8-hour ozone averages do not define AQI values greater than 300; AQI values of 301 or greater are calculated with 1-hour ozone concentrations. 1-hour SO2 values do not define higher AQI values greater than 200. AQI values of 201 or greater are calculated with 24-hour SO2 concentrations.
Real time monitoring data from continuous monitors are typically available as 1-hour averages. However, computation of the AQI for some pollutants requires averaging over multiple hours of data. (For example, calculation of the ozone AQI requires computation of an 8-hour average and computation of the PM2.5 or PM10 AQI requires a 24-hour average.) To accurately reflect the current air quality, the multi-hour average used for the AQI computation should be centered on the current time, but as concentrations of future hours are unknown and are difficult to estimate accurately, EPA uses surrogate concentrations to estimate these multi-hour averages. For reporting the PM2.5, PM10 and ozone air quality indices, this surrogate concentration is called the NowCast. The Nowcast is a particular type of weighted average that provides more weight to the most recent air quality data when air pollution levels are changing.[40][41] There is a free email subscription service for New York inhabitants – AirNYC.[42] Subscribers get notification about AQI values changes for selected location (eg home address), based on air quality conditions.
Public Availability of the AQI
Real time monitoring data and forecasts of air quality that are color-coded in terms of the air quality index are available from EPA’s AirNow web site.[43] Historical air monitoring data including AQI charts and maps are available at EPA’s AirData website.[44] Detailed map about current AQI level and its two day forecast is available from Aerostate web site.[45]
History of the AQI
The AQI made its debut in 1968, when the National Air Pollution Control Administration undertook an initiative to develop an air quality index and to apply the methodology to Metropolitan Statistical Areas. The impetus was to draw public attention to the issue of air pollution and indirectly push responsible local public officials to take action to control sources of pollution and enhance air quality within their jurisdictions.
Jack Fensterstock, the head of the National Inventory of Air Pollution Emissions and Control Branch, was tasked to lead the development of the methodology and to compile the air quality and emissions data necessary to test and calibrate resultant indices.[46]
The initial iteration of the air quality index used standardized ambient pollutant concentrations to yield individual pollutant indices. These indices were then weighted and summed to form a single total air quality index. The overall methodology could use concentrations that are taken from ambient monitoring data or are predicted by means of a diffusion model. The concentrations were then converted into a standard statistical distribution with a preset mean and standard deviation. The resultant individual pollutant indices are assumed to be equally weighted, although values other than unity can be used. Likewise, the index can incorporate any number of pollutants although it was only used to combine SOx, CO, and TSP because of a lack of available data for other pollutants.
While the methodology was designed to be robust, the practical application for all metropolitan areas proved to be inconsistent due to the paucity of ambient air quality monitoring data, lack of agreement on weighting factors, and non-uniformity of air quality standards across geographical and political boundaries. Despite these issues, the publication of lists ranking metropolitan areas achieved the public policy objectives and led to the future development of improved indices and their routine application.