CNET's key takeaways

• The Windmill AC normally starts at $339 for 6,000 BTUs, but you can find it on sale right now at Windmill's website or Amazon for $279, ($60 off). 
• Not only is the Windmill AC the easiest unit I've ever installed, it's the only AC unit I've tried that effectively kept my older and not well-insulated home cool during heat waves. 
• Bonus: It's actually stylish. (I still would have paid for an ugly one that works.) 

There are a lot of things I love about living in an older home -- my 100-year-old rental has original 1920s art deco tile, tall ceilings, and a lot more character than you might find in a newly constructed house. One thing it doesn't have? Central air conditioning.

With record-breaking heat waves regularly hitting in my area, I needed to find window ACs that could cool my poorly insulated 2,500 square foot home.

I hunted for the right one for years. Every summer I'd buy and test out new window air conditioners, only to feel frustrated by how poorly they worked. I'd sell them at the end of the season, and restart the cycle again the following year.

Finally, after years of sweating through sweltering three-digit temperatures and overbearing humidity, I found it: the Windmill WhisperTech window air conditioner. This innovative powerhouse was so effective at cooling my oversized master bedroom, that I eventually bought two more. These three AC units effectively cool my 2,500-square-foot Philadelphia row home even during intense heat waves. And they look great while they do it.

The Windmill AC isn't the cheapest option on the market, but for me, it was well worth every cent. If you're also fed up with sweating indoors, here's why you need to try this game-changing AC.

My experience with the Windmill air conditioner

I was skeptical about the Windmill window air conditioner when it first arrived. It was lighter than other units I'd tried out (I could pick it up myself), so I panicked, thinking there was no way this one could cool our south-facing 350 plus square foot bedroom.

But within minutes, my partner and I had the unit installed and running. Only a few hours later, our bedroom felt less like a sauna and dropped to 68 degrees Fahrenheit -- a feat that hadn't happened with prior ACs. The humidity, which often jumped up to 65% or higher on humid days also dropped to below 50%. I was equally impressed by how well it maintained its set temperature, too. Especially during intense heat waves. 

The very next day, I ordered a second unit for the other end of our house.

Note: CNET does scientific testing on window ACs at our Louisville testing labs. In our recent comparison of window and portable AC units, the Windmill 8k was found to be the top-performing window AC unit.

What makes the Windmill AC different?

Windmill air conditioners have a few unique features, but what prompted me to add one to my cart was the unit's cooling design. Windmill ACs push cool air out of the top of the unit at a 45 degree angle for better cooling. After trying several big name window ACs that pushed air out horizontally, I was excited to find that this feature actually cooled a second-story room with a tall ceiling; the air seemed to circulate better since the unit pushes the cold air up, rather than out and down.

No need to hide the ugly Window AC

I'd deal with an ugly air conditioner as long as it cooled my home. But I'm glad I don't have to. The Windmill air conditioner has a sleek, minimal design that many of my friends and family have commented on. The unit has an attractive front panel design that hides its air filter and houses tiny buttons that are nearly hidden at the top of the panel. 

The LED display lights automatically dim, so you don't have to worry about any visual disruptions at night. It also comes with side panel covers that offer extra insulation and a seamless look.

Windmill also offers colorful magnetic panel fronts to add some whimsy to your window, if you're into that kind of thing. 

It's the quietest AC I've ever owned

Although it wasn't a main selling point for me, I'm now a huge fan of Windmill's Whispertech quiet cooling technology. My first priority was an air conditioner that made my house feel comfortable; I just assumed that would come with some noise. The specs list it as 42 decibels -- softer than the average household refrigerator. I found my Windmill units comfortably quiet, even after regularly using two for almost three years.

My partner and I are able to watch TV at a normal volume, talk to each other from other ends of the house and jump on work calls without the noise bothering us. I actually enjoy the white noise effect it offers in our bedroom at night.

I do sometimes find the running noise distracting when I'm on work calls, but that would happen with any AC since my window is right next to my desk. This typically only happens if it's on high or medium, so I just switch it to low or eco-mode to solve this problem.

You can install it in minutes (really)

I've installed three of these units in multiple homes and windows, and it only takes me five to ten minutes to set up. That's because this unit comes pre-assembled. There's no attaching panels or screwing brackets onto the base before installing it.

All you have to do is add the window foam to the sides of your windows, set the unit onto your window pane, expand the side panels, shut your window, then secure it with screws. If you can't drill into your window panes or if you rent (like me) and don't want to, you can secure it to a block of wood. 

I usually have my partner help me install this (one of us lifts while the other opens and lowers the window), but I've successfully installed it on my own in the past. 

It comes with a smart app and voice control

Windmill will send a remote with your window AC, but if you have multiple units to control, I highly recommend using Windmill's smart app. It takes just a few minutes to install and register your device (they send a QR code you can use to make set up even easier). 

The app's easy to use and helpful if you leave the house and forget to adjust the temperature before you go. It does occasionally show the wrong temperatures, though. I had an issue with my office AC's temperature on the app showing as 61 degrees when it clearly wasn't, but a quick reset of the AC solved that.

Similar to a smart thermostat, you can create automations to lower or raise the temperature, speed or even shut the unit off at certain times of day. It's a great tool if you want to raise the temperature while you're at work or away for a weekend.

I don't use the voice control with Alexa feature, but if you're into that, it seems easy to set up.

Eco mode keeps my energy bill low

Since I have gas heat, my electric bill tends to go up in the summer when I'm running the AC. While that's still the case, I don't worry about large energy bill surges anymore. Windmill's eco-mode helps my rooms stay cool without causing a surprise electric bill. 

Windmill air conditioners are Energy Star rated, with up to a 15 Combined Energy Efficiency Ratio rating. To earn an Energy Star rating, air conditioners need a CEER rating of 12 or higher. 

Solves the storage dilemma

I'm lucky to have a basement where I can store my air conditioners when I'm not using them. But if you don't have an extra closet or garage to house these units during the winter, Windmill sells winter covers that will protect your unit, keep your house insulated, and add a pop of color (if you choose) to your window.

I like this idea, although the current options are fairly limited and I don't personally love any of the color schemes they offer.

The specs

• 6,000, 8,000, 10,000 and 12,000 BTU units available. 
• Pre-assembled for easy installation
• WhisperTech quiet technology
• The 6,000 BTU unit is 42 decibels
• Comes with side panel covers for extra insulation and a seamless finish
• Airflow at a 45 degree angle
• Auto-dimming LED lights
• Three cooling options
• Three fan speeds
• Eco-mode
• Remote control
• Smart app and voice control
• One-year limited warranty
• The 6,000 BTU unit retails for $350, but we usually see it on sale for  $340. The 12,000 BTU retails for $629 and often on sale for $589. 

CNET's buying advice

I recommend Windmill window air conditioners to everyone I know who's looking for one. My experience with the three units I own has been nothing but positive. They've outperformed GE and Midea air conditioners I've tried in the past and work well to keep my humid row house cool and comfortable.

The biggest drawback of the Windmill air conditioner is its price. While the cost is on par with competitors like July (yes, they're an AC company named after one of the hottest months of the year) and Midea, you can find more affordable options. Paying $630 for a 12,000 BTU window air conditioner is a steep price, but you can frequently find them on sale at Windmill's website or at Amazon, Home Depot, Lowes, P.C. Richards and Costco.

If a Windmill AC isn't in your budget, don't go into debt to buy one. Instead consider the GE 5,000 BTU mechanical window air conditioner, CNET's best budget pick, the GE AHEC05AC window AC for around $160-170.