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After new tests, our picks are changing: We recommend the Vornado Transom as a first option and the Bionaire Twin Reversible Airflow Window Fan as a budget pick. Shaker Sifter
Window fans may seem like a viable alternative to window air conditioners. They’re not. But they can come in handy in certain situations, such as in mild, dry summer weather, or when you need ventilation and air circulation and can’t spare the floor or shelf space for a standard room fan. For those situations, get the Vornado Transom. It’s quieter and significantly more powerful than any other window fan we’ve tested in nearly a decade, yet it uses half as much energy to get the job done.
The quietest, strongest, and most efficient window fan we’ve tested stands apart from all competitors, though it is a bit more expensive.
This variant of our top pick adds voice commands and smart-home capabilities.
This model is the most powerful of the standard twin window fans we’ve tested, but it’s not without its shortcomings.
The quietest, strongest, and most efficient window fan we’ve tested stands apart from all competitors, though it is a bit more expensive.
In our tests, the Vornado Transom produced a powerful yet pleasant breeze that filled the entire room with enough strength to shake strings and sheets of paper more than 24 feet away—and it did that while using half as much energy as the competition. It’s roughly half as tall as the competition, too, with a sleek modern design and sturdy foam side pads that help you get a much tighter seal on the window frame. In addition, the Transom comes with plenty of other thoughtful features, including an auto-dimming LCD control panel, a remote control, and a weather-resistant design, as well as a reliable five-year warranty. It’s not the easiest fan to clean, but otherwise it’s the best window fan we’ve tested in more than seven years of firsthand comparisons.
This variant of our top pick adds voice commands and smart-home capabilities.
The Vornado Transom AE is identical to our top pick in every way but replaces the remote control with the convenience of built-in Amazon Alexa integration. This version is simple to set up, and natural voice commands make it easy for you to turn the fan speed up or down, to switch the fan from intake to exhaust after you accidentally burn your dinner, or even to turn the fan on from the comfort of your bed.
This model is the most powerful of the standard twin window fans we’ve tested, but it’s not without its shortcomings.
The Bionaire Twin Reversible Airflow Window Fan was nearly as powerful as our top pick, producing robust breezes up to 10 mph that could make a string dance from 24 feet away, about 8 feet farther than other, similar dual-blade window fans could reach. Clearly marked buttons allow you to control speed and temperature, and another button reverses the fans’ direction, switching them from pulling in fresh outdoor air to expelling indoor air. But this fan has drawn some buyer complaints—and among those concerns are problems we’ve encountered ourselves in retests of this model. Bionaire has been inconsistent in its customer service, too. Still, it’s the best version of a basic window fan we’ve found, outperforming similar competitors in spite of its flaws.
We’ve been reviewing window fans since 2016. Between this guide and our guide to the best fan, we’ve spent more than 100 hours researching, testing, and living with fans to understand what it takes to move air effectively throughout a room. We’ve interviewed several researchers who have devoted their entire careers to understanding how to most effectively cool spaces, including Danny Parker, a principal research scientist at the Florida Solar Energy Center; Paul Raftery, PhD, a researcher at UC Berkeley’s Center for the Built Environment; and Edward Arens, PhD, the director of UC Berkeley’s Center for Environmental Design Research.
Circulate and ventilate, while saving space: If you live in a moderate, low-humidity climate with warm days and cool nights, a window fan can circulate outdoor air into your home without taking up any floor space. As a bonus, it can also ventilate a room—if your kitchen doesn’t have a range hood, for example, and you’re concerned about emissions from your gas stove, or if you want a quick way to clear out the stench from popcorn that spent too long in the microwave.
Set up a continuous breeze: If you can install a pair of window fans, to draw cool outside air in from the shady side of your home while blowing hot indoor air out on the sunny side, that’s ideal. As Danny Parker of the Florida Solar Energy Center explained, this setup creates a continuous, full-house cross breeze, which makes the fans even more effective at circulating air and cooling the space.
Keep storage needs in mind: If you need to use the window, the fan gets in the way. To open the window, shut it, or use it for a window air conditioner, you have to remove the fan and stow it somewhere.
Consider a room fan: In most cases, we’ve found that room fans can circulate more air and use less energy. Our testing backs up the notion that you can get effects similar to those of a window fan by putting a high-performing room fan near an open window on mild days—or, in hotter weather, using a room fan to amplify the effects of a window AC or a central HVAC’s floor register.
Circulating indoor air can make warm days a lot more comfortable.
We started by compiling an exhaustive list of all of the window fans for sale at major retailers such as Amazon, Home Depot, Lowe’s, and Walmart. We pored over buyer reviews of these fans, keeping an eye out for any patterns of inconvenience, failure, or time-tested durability problems.
With all of that in mind, we looked for several basic criteria:
Most fans have an internal thermostat, which in theory should turn your fan on and off when your room reaches a certain temperature. But in our years of testing, we’ve never encountered one precise enough to work, so we don’t prioritize this feature in making our picks.
We installed each fan in a standard double-hung window and ran it for hours, day and night. We evaluated the setup process and the usability of each fan’s controls, watching for anything clunky or confusing.
Power consumption and noise: We plugged each fan into an energy monitor and checked it at each power setting. We then used a handheld decibel meter to quantify the noise that each fan emitted at various power settings. Because decibel readings don’t perfectly correlate to perceived sound, we used the Audio Spectrum Analyzer iPhone app to pinpoint any problematic frequency ranges.
Wind speed: We first used an anemometer to measure each fan at different settings. Afterward, we evaluated the contenders more subjectively by putting each one on its highest setting and observing the movement of a generic store receipt to measure the effective distance of the breeze the fan created.
The quietest, strongest, and most efficient window fan we’ve tested stands apart from all competitors, though it is a bit more expensive.
We’ve been reviewing window fans since 2016, and the Vornado Transom is the first model we’ve evaluated that actually did all the things we wanted in our tests, and did them well. This model dispenses with the dual-fan design that has become common among window fans, instead offering just one long fan that spans almost the entire width of the unit. As a result, the Transom is shorter than other window fans—about 7 inches tall, as opposed to 12 inches or more—and its stocky shape is much better suited for sitting on a window sill.
It’s the most powerful window fan we’ve tested, by far. We measured an airspeed velocity of about 10 mph coming out of the Transom when it was running on low and 11 mph on high. With those results, it was nearly twice as fast as the Genesis and Holmes models we tested and a bit faster than our former top pick (and current budget pick) from Bionaire. Put into practice, the Transom was capable of moving a string from 24 feet away, while the Genesis and Holmes window fans both barely made it to 16 feet. The draft the Transom created was also much more pleasant throughout the room than the gusting from the similarly powerful Bionaire fan, which felt more like a targeted wind tunnel than a room-wide breeze. That’s because, like most Vornado products, the Transom is designed to circulate air all around a room instead of just pushing it straight ahead.
It uses half as much energy as the competition. In our tests, the Transom consumed about 26 watts on low and 29 watts on high, versus a range of around 50 to 70 watts for the other models we tested. Based on current average US energy rates, this Vornado fan would cost you about $7.50 to run nonstop on high for three straight months (the entire summer, in other words). In contrast, running our budget pick from Bionaire would cost you a little under $18. That $10 might not seem like the most significant energy-cost savings, but after a few years, it more than makes up for the roughly $30 price difference between the two fans, and you get to have a more pleasant experience overall.
It’s noticeably quieter. On the Transom’s highest setting, we measured its noise at about 49 decibels—about as quiet as the other tested window fans on low. There were no ear-splitting stray frequencies, either, just the nice, pleasant white-noise rumble of a fan fading into the background. It’s the kind of sound that might help some people focus or fall asleep.
It has unusually attractive and intuitive controls. These consist mainly of a small LCD screen at the lower-right corner. The panel dims automatically, a feature that we appreciated in a bedroom at night. The clearly marked controls let you turn the fan power up or down, set the (questionable) thermostat, or switch between the intake and exhaust settings.
It’s easier to install than other window fans. The Transom is also more versatile, as it can fit in windows up to 40 inches wide, while the other window fans we tested all maxed out at 37 inches. Because it’s shorter than most other window fans, it’s much more well balanced than tall, floppy dual-fan models. Foam-covered overhangs on the top and bottom improve its seal along the edge of the window, and included in the box is a set of six foam blocks that you can wedge between the fan and the window jambs on the side of the frame to hold the fan in place and improve the seal. In our experience, this foam system worked much better than the accordion-like wings attached to most other window fans, but it’s not perfect. Vornado also sells replacement sets of foam pads, so no need to worry if you lose them between the seasons, say, or accidentally drop one into the alleyway abyss behind your apartment building.
It actually resists weather. For starters, unlike every other window fan we’ve tested, the Transom doesn’t explicitly warn you not to expose it to the elements. (Believe it or not, most other window fans specifically have “NOT FOR OUTDOOR USE” somewhere on their packaging, despite the fact that they are literally designed to sit in a window and straddle the inside and outside of your home.) We can tell you from personal experience, too, that the Bionaire and Holmes models will not hold up through a good ol’ New England nor’easter, whereas the Transom has continued to endure through several such storms. If anything does go wrong, Vornado backs the Transom with a reliable five-year warranty.
Cleaning is a pain. Fans get dirty. This is no one’s fault; it’s just what happens when a machine is moving lots of air. Unfortunately, window fans in general aren’t easy to clean, and the Transom is no exception. Vornado recommends vacuuming the outside of the unit, but there’s no simple way to reach the blades inside if they get mucked up with dog hair or whatever else they suck in.
A perfect seal is elusive. Like any window fan, the Transom works better when it has less air infiltration around its sides, regardless of whether you’re running it on intake or exhaust. As much as we liked the foam pads included with the Transom, they still left some small gaps between the fan and the window frame. (Related issue: bugs.) We recommend picking up some extra foam weatherstripping tape, which is a standard upgrade to window fans for optimal results.
It ain’t cheap. The $100 price tag on this window fan might seem a little steep to you. We agree. But we also didn’t think it was right to make this model an upgrade pick, when it’s really the only window fan out there that does what it’s supposed to. An extra investment is always worth making if it gives you something that actually works.
The remote control is … meh. While the onboard control panel is easy and clear, the tiny remote control that comes with the Transom is sadly unintuitive. The best we can say about it is that it’s a remote control, and it looks sort of sleek (at least until you lose it, as we did more than once). It’s a good thing the Transom offers alternative control options that are better and more convenient.
This variant of our top pick adds voice commands and smart-home capabilities.
If you want the best window fan available with the convenience of smart-home capabilities, get the Vornado Transom AE. It’s just as powerful, just as quiet, and just as easy to set up as our top pick, with the bonus of built-in Alexa integration. The “Works with Alexa” chip makes the connection nearly automatic, and the voice-command options are as natural and intuitive as Alexa voice commands can ever be—“Set Transom to exhaust,” “Turn Transom to 4,” and so on. You don’t even have to worry about losing an awkward little remote control.
This model is the most powerful of the standard twin window fans we’ve tested, but it’s not without its shortcomings.
We’ve listed the Bionaire Twin Reversible Airflow Window Fan as a pick since the first time we tested window fans, in 2016. It’s more powerful than typical barebones window fans, with better controls and more options, and setup is easy, too. But it’s weaker and louder than the Vornado Transom, and Bionaire has been inconsistent in quality control and customer service over the years.
It was the second strongest fan in our tests. According to our measurements, it moved air at about 7.8 mph on low and 10.1 mph on high—it’s a bit slower than our top pick but noticeably stronger than any other window fan we’ve tested. Thanks to its 8.5-inch dual-fan setup, those gusts moved with gusto, too, easily making a string flutter from some 24 feet away, or about 8 feet farther than the competition managed (again, with the exception of the Transom). Unlike our top pick, however, this Bionaire model doesn’t circulate air around the room: You can feel the breeze full-blast when you’re standing right in front of the fan, but you might not notice it when you’re standing off to the side.
It’s easy to use. The controls on this Bionaire window fan are especially straightforward in comparison with the user interfaces on other, similarly designed fans like the Genesis and Holmes models we tested. One button powers the fan on and off and adjusts the power level between low, medium, and high. Separate controls each handle the fan’s auto/manual setting, the temperature of the thermostat, the airflow direction (intake/exhaust), and the brightness of the LED screen that displays the temperature. (Unlike on the Transom, you can’t turn this model’s display off all the way.) You may think that all of that is to be expected, but during our testing, we found that the Genesis fan, for example, had neither a power button nor an auto/manual option, and its temperature control overrode the fan speed, locking it on high. Things got worse with the Holmes model’s all-in-one control button, which required us to cycle through every possible setting in order to reach the one we wanted.
But it occasionally fails. To make matters worse, though this model is technically covered by a five-year warranty, similar to our top pick, some owner reviews have reported trouble getting Bionaire to honor that commitment. In some cases, the company replaced a broken Bionaire fan with a cheaper fan such as the Holmes Dual Blade Twin Window Fan, despite the fact that the warranty (PDF) explicitly states that a “replacement may be made with a similar product of equal or greater value.” To be fair, the warranty documentation says a lot of things that are so broad as to be essentially meaningless.
In long-term testing, we’ve seen Bionaire fans from the mid-2010s perform extremely well. We found a quality decline in our 2019 retesting. In our most recent testing, from 2022 to 2023, this Bionaire model outperformed all competitors except for the Vornado Transom.
In 2023, we tested the Lasko Reversible Twin Window Fan with Bluetooth W09560, a model that is comparable to our budget pick from Bionaire but adds Bluetooth support for you to control the fan from your phone via the Lasko Connect app. This works well enough, but if you’re going to pay a premium for smart features, you may as well just get the Vornado Transom AE. This Lasko model does have blue fan blades, however, which look kind of neat against the all-white chassis.
We previously recommended the Genesis High Velocity 9 Inch Window Fan as a distant runner-up to the Bionaire Twin Reversible Airflow Window Fan. The only thing that sets this model apart from the Holmes Dual Blade Twin Window Fan with Comfort Control Thermostat (which we’ve always dismissed) is that the controls on the Genesis fan are slightly less terrible. In our airspeed measurements, both fans moved air at about half the speed of our top pick from Vornado while using twice as much energy. In our most recent tests, the accordion wings on the side of the Genesis fan snapped during the installation process. And when the Genesis model ran on medium or low, it emitted a high-pitched whining, which we measured around 5.4 kHz, 11 kHz, and a mind-flaying 19 kHz.
As for the thermostat-equipped Holmes Dual Blade Twin Window Fan, the best thing we can say is that it didn’t reach the 19 kHz frequency of the Genesis model, though it still had all the other awful overtones. The real problem with this fan, in addition to its relatively weak airflow, is the user interface. It has only one button, labeled “mode,” that controls both the speed and temperature and turns the fan on and off. This design means that you must press that lone, loathsome button to cycle through both speeds for each of the five temperatures listed in the thermostat.
When the Pelonis 9-Inch Twin Window Fan was discontinued, we tested a very similar replacement, the 65-Watt 9-Inch White Reversible Twin Window Fan from Home Depot. This brandless fan did not have a particularly powerful airflow, moving only as much air as the Holmes Dual Blade (13 feet, versus 24 feet for our budget pick from Bionaire and 16 feet for the Genesis model, in our “receipt test”). One of the knobs fell off when we tried to turn it.
The Bionaire Compact Window Fan stands at 8 inches vertically, so it takes up less room than typical window fans, and its thin shape allows you to install it in sliding windows. However, its lack of a reverse-airflow switch and mixed owner reviews led us to dismiss it.
The alluringly inexpensive Holmes Dual Blade Twin Window Fan with Reversible Air Blades pierced our ears with its shrill motors and tested our patience with its barely-there breeze.
The Comfort Zone Reversible Twin Window Fan with Remote Control and the Lasko Electrically Reversible Twin Window Fan 2138 rival our budget pick from Bionaire in features, but both models had disappointingly mixed reviews at the time of our research.
During our research period, the Optimus 8-Inch Reversible Twin Window Fan did not have enough customer reviews to speak to its longevity and performance, and it was too expensive for its limited set of features.
This article was edited by Harry Sawyers.
Danny Parker, principal research scientist at the Florida Solar Energy Center, phone interview, August 2, 2018
Paul Raftery, researcher at UC Berkeley’s Center for the Built Environment, phone interview, August 2, 2018
Edward Arens, director of UC Berkeley’s Center for Environmental Design Research, email interview, July 31, 2018
Chris Galas, senior product manager at Jarden Consumer Solutions, phone interview, August 7, 2018
Steven Fox, Bob Vila, The Do’s and Don’ts of Window Fans, Bob Vila, August 22, 2018
Patrick Allan, Keep Your Room Cool at Night by Facing Your Fan Out, Not In, Lifehacker, July 24, 2014
Thom Dunn is a staff writer at Wirecutter reporting on heating, cooling, and other home-improvement topics. Sometimes his curiosity gets the best of him, such as when he plugged a space heater and a Marshall guitar amp into the same power strip. Pro tip: Don’t do that.
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