Recently, I had a conversation with someone who had just moved cross-country to a new apartment. “Got that Windmill hooked up to the window,” she told me, as if she were name-dropping her cable company. “It’s lit.”I had seen the minimalist window air conditioning units in the background of some home decor Instagram posts, but didn’t realize the company, which launched in 2020, had become another direct-to-consumer household name. The design-y devices are advertised as being quieter and more eco-friendly. As I researched the company on my phone before bed, my dusty, 4-year-old window unit roared in the background. “Wouldn’t it be nice to upgrade the AC situation?” I wondered aloud to my partner, who complained nightly about our bedroom being too warm to sleep.In a sure sign that manifestation works, I got an email from the company the very next day, announcing a new program designed to lower the air conditioner’s impact on my local electric grid. I requested a unit to review and immediately moved my old AC to the other end of my New York City railroad apartment. After using the 8,300 BTU Windmill AC for three weeks, I can confidently say that the machine proves that an efficient air conditioner doesn’t have to be ugly. Read on for my full review of the Windmill AC.We at Bustle only include products that have been independently selected by our editors. We may receive a portion of sales if you purchase a product through a link in this article.BDG product reviews and recommendations are written and conducted by writers and editors with expertise in their fields. Testers often have specific experience with the situation or product at hand, and/or their review or recommendation is provided in consultation with experts. You can learn more about our standards here.The Windmill is most notable for its minimalist aesthetic. The matte white machine has rounded edges and soft LED illumination announcing the current temperature. You know that ugly plastic expandable thing that comes with a typical AC to close the side gaps between the unit and the window? Windmill replaced that with a matte white insulator that seamlessly seals off your apartment from the outside world. Objectively, it looks very nice as a windowsill accessory.What most intrigued me about the Windmill, however, were the company’s sustainability claims. As climate change warms the planet, people will require more air conditioning to stay safe, but the machines have a serious environmental impact: 16% of all buildings’ electricity consumption is taken up by cooling, per a 2021 report from the International Energy Agency, an environmental policy intergovernmental organization.Windmill’s sustainability promises include a carbon offset program, using more eco-friendly refrigerant (a chemical linked to ozone layer damage and other harms), and remote control efficiency. I also enrolled my account with the company’s Eco Rewards program, which remotely lowers your AC use during peak demand — protecting the energy grid during, say, a heat wave — in exchange for up to $60 cash back. This program is only available in New York City, however, and I didn’t see it going into effect during the early summer weeks when I tested the AC.The Windmill arrived in a box that was way too bulky for me to carry upstairs on my own. With my partner, however, we maneuvered the device into our bedroom window. It was easy to install, sliding into place between my window sash and sill. It took a minute to download the app, create an account, and link the unit with my Wi-Fi, but after that, it was smooth sailing.The Windmill has your classic AC settings — fan, cool, or eco modes; auto, low, medium, or high fan speeds — which you can adjust in the app, via physical buttons on the front panel of the machine, or via remote. You can also set up automations — things like turning the unit off at a certain time each day — in the app, as well as control the device remotely. There’s even a night mode to turn off the unit’s indicator light while you sleep. One nice detail: The air is siphoned out through the top of the unit, so you don’t get a blast of cold air in your sweat-soaked face. Perhaps this is a downside if you like that immediate, icy sensation that cooling relief is on its way, but I didn’t miss it.During the three weeks I tested the Windmill AC, my Windmill was set up in my bedroom, while I moved my old AC to cool my kitchen and living room on the other side of my apartment (a roughly equivalent size). I used the Windmill AC consistently the same way I used my other unit, putting it on eco mode during the day and cool mode at night.The two areas of my home, which were separated by a door I kept closed, were not noticeably different in coolness, but the bedroom, where the Windmill was, was significantly quieter. Working in my bedroom, I barely noticed eco mode click on, whereas in my living room, the sound was distracting. The device’s clean design was a welcome addition to my bedroom, too.At the beginning of week three, however, there was an unexpected red light on the Windmill’s display, indicating that I needed to clean the filter. Though I live in a gross, polluted city, I have never once in my life changed an air conditioner filter — needing to do so after just two weeks of use seemed excessive. (A representative for Windmill confirmed that the unit is in “overdrive” improving air quality during the first week of use; after that, filter replacement and cleaning won’t be needed as often.) The filter housing pops off the front of the device and reattaches magnetically, and you can simply rinse the filter under cold water. This made the process less annoying than I expected.Starting at $365 for the 6,000 BTU model, launched this past spring, the Windmill AC is priced about $100 to $150 more than units with similar capabilities on Amazon. Though Windmill does offer a $50 credit off a new device when you recycle your old AC, that price difference may be too much to stomach for what essentially boils down to aesthetics. That said, other highly rated, not-ugly window AC units on the market are even more expensive — July, another startup, starts at $449 for 6,000 BTUs, while the Energy Star-certified Frigidaire Gallery will run you $599 for 12,000 BTUs.The Windmill AC works just about the same as any other AC you’ve ever used. What sets it apart is how quiet it is and how it blends into the background of your home decor (or your Instagrams, if that’s important to you). If you value a quiet and cool sleep with an elevated design to match, the Windmill is your best bet.