Windmill Air Conditioner review: Silence sounds cool

Windmill's WhisperTech is proof that, when it comes to a quieter window AC, you can have your (ice cream) cake and eat it too.
Windmill AC with WhisperTech in an apartment window (color-corrected header)
Brandt Ranj

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For city dwellers, air conditioners humming is an omnipresent summer sound, as familiar as the melody of birds chirping and ice cream trucks chiming. But what if it didn’t have to be like that? For the past few weeks, I’ve tried the latest generation of the Windmill AC with WhisperTech, and this efficient, easy-to-install, WiFi-enabled window unit is a game-changer for anyone who wants to keep cool without getting an earful of white noise while working or trying to sleep.

Windmill AC WhisperTech


  • Windmill developed WhisperTech, a new technology that offers the same air conditioning performance while making less noise.
  • Installation and setup can take as little as five minutes, and the air conditioner is compatible with most windows that open upward and downward.
  • The air conditioner’s minimalist look isn’t necessary, but Windmill’s focus on aesthetics and simplicity extends from the hardware to the software, creating a welcome harmony.


  • WhisperTech lives up to its name
  • Can be controlled remotely using a streamlined mobile app
  • Incentives are there to make the air conditioner eco-friendly


  • Expensive
  • The most powerful model only covers rooms up to 450 sq. ft.

Verdict: If your window unit’s sound irritates you, but you still need a way to beat the summer heat, Windmill’s WhisperTech makes its latest AC hard to beat.

The build

What if an air conditioner didn’t have to suck? This seems like the question the designers at Windmill asked themselves during the development of their first-generation model, which was released a couple of years ago. The company has just released a new energy-efficient air conditioner, which builds upon the successes of the original with a new technology it developed called WhisperTech, which makes the AC up to nine times quieter than traditional models, according to Windmill. After listening to what the 8,000 BTU version does, or maybe that should be what it doesn’t do, I can recommend the Windmill AC with WhisperTech to anyone looking to upgrade from an old air conditioner before the summer, especially if you need a unit for your bedroom.

To its credit, Windmill didn’t try to fix what wasn’t broken in an attempt to make this new air conditioner overly complicated to install or use. It has the same minimalist look as the original model (with its auto-dimming LED display), comes bundled with the same accessories, uses the same app, and has an identical installation process. Windmill simply added a welcome feature, and even offers its original air conditioner alongside the new one.

The setup

Installing the Windmill AC with WhisperTech took about five minutes. All you really need is a single- or double-hung window that’s 23-37 inches wide and can open 14 inches (no through-the-wall, no casement, and no slider windows). The air conditioner comes with strips of insulation, which can be placed on the bottom of your window to prevent outside air from getting in and to ensure your air conditioner fits snugly. The AC unit comes in a single piece, and once it was unboxed, I put it into my window, extended its accordion-like arms, and closed the top window sash on top of it. The top frame of this air conditioner has three holes, which you can use to screw the unit into your window to hold it securely. My landlord doesn’t want any more holes in the window and instead uses a fitted piece of wood between the top window sash and frame to hold AC units in place.

Windmill includes a set of cosmetic side panels, which match the top and bottom of the air conditioner to make the unit look even more sleek, but I actually prefer the out-of-box look. The company went so far as to include a pair of scissors with its air conditioner, so you can cut the panels to fit the exact size of your window—this is a nice touch and impressive detail. The second (and technically optional) part of setting up this air conditioner is connecting it to your home’s WiFi network with Windmill’s app (available for iOS and Android). This allows you to control the AC from your phone at home or remotely (there’s also an included remote if you prefer that when in the house). This might sound like it could be tedious, but Windmill streamlined the onboarding process, and I got it on my WiFi router and added to my many smart devices within about 10 minutes. You can also connect the Windmill AC unit to Google Assistant and Amazon Alexa for voice control.

Windmill AC app on an iPhone
Windmill’s mobile app puts all the air conditioner controls in your pocket. Brandt Ranj

The performance

So, how does it sound? It’s weird because I’ve never really listened to an air conditioner before. It seemed unnecessary because the assumption was every AC would sound kind of like a tractor in the far distance. Windmill’s WhisperTech has me rethinking my entire approach. I keep the Windmill AC on eco mode (its default), and my Apple Watch’s microphone registered it at about 57 decibels from roughly six inches away. That number dropped into the 40s when I moved to the couch. This number is impressive because it means you could sit right next to Windmill’s air conditioner all day without it causing any hearing loss—in fact, you’re liable to tune it out as I did.

The reason for this air conditioner’s quiet behavior is the switch from a fixed-speed compressor with a rotary fan to a variable-speed compressor with a linear fan. Switching to more adaptable components allows the Windmill to dynamically cool your room, getting a little louder or softer automatically if need be. Practically speaking, turning up the air conditioner’s fan speed to high, or switching from eco to cool mode, increased the noise some. However, the AC is so efficient at cooling my room that toggling those settings never felt necessary. It’s like the highest gear on a car—rarely important, but nice to have when necessary.

It could be tempting to crank this air conditioner to its highest setting (generally quiet) to cool your room down as quickly as possible, but I never felt the need. Windmill’s air conditioner sucks hot air from your room through a vent on the bottom and shoots cold air out the top. This approach makes the AC much more efficient at cooling a room—I could feel the effects within a few minutes—and gets you to your target temperature more quickly. The eco mode on the Windmill AC, which the company says is 35% more efficient vs. the minimum efficiency standard, works as well as the high cool setting on similarly sized models.

The eco mode will also shut off your air conditioner after it reaches your set temperature rather than continually blasting cool air until you ask it to stop. And if you’re in parts of California and New York, Windmill will also incentivize you to keep the air conditioner on eco mode by offering to enroll you in its Eco Rewards program, which automatically adjusts the AC’s settings to be less burdensome to your power grid. You can opt out of Eco Rewards anytime, but sticking with it can earn you up to $10 in cash or a four-pack of activated-carbon filters (a $65 value), which help protect against fumes, odors, smoke, and volatile organic compounds.

So, who should buy the Windmill AC with WhisperTech?

Plan to purchase an air conditioner in 2023? The Windmill AC with WhisperTech should be near the top of your list, so long as you plan on keeping it in a room that’s not much larger than 365 sq. ft. Its $399 price tag—tack on an extra $100 if you’d like the larger 10,000 BTU model that covers up to 450 sq. ft.—isn’t cheap, but you’re getting what you pay for. The good-looking, easy-to-install air conditioner won’t interrupt you while you work and can keep you cool all summer long.


Brandt Ranj Avatar

Brandt Ranj

Staff Writer, Commerce

Brandt Ranj is a commerce reporter at Popular Science. He writes about the latest and greatest gadgets, from headphones and TVs to chargers and cables. He splits his time between New York City, Long Island, and Croatia, carting test gear around the U.S. and the globe.