Mini splits vs. window ACs: Pros, cons, and prices

Ductless cooling is the way to go if you can afford it—but window ACs have improved, too.

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Updated Apr 11, 2024
5 min read

Central air conditioning is the norm across most of the U.S. But for those of us who live in parts of the country where radiator heating reigns, window ACs have been a way of life. 

Many of our classic homes and public buildings have no existing ductwork and no easy, affordable way to install it. We see it right outside the window of the EnergySage offices in Boston: The Suffolk County Courthouse has at least 150 window ACs installed across 19 stories, by our count.

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In the Northeast, we’ve learned to endure the ritual indignity of Installation Day: Grunting and cursing as we haul our lopsided, slightly-too-wide-for-the-doorway window units out of storage, hoping that we don’t slip a disk or drop the AC out the window while we settle it onto its precarious perch.

Say goodbye to that window for the next four months! Then get ready to do the same thing in reverse. Here’s a jar of earplugs to help you sleep through the night in case the compressor is too loud. Did this thing grow mold in the basement? Now go do the same thing at your mom’s house tomorrow.

If you’re tired of that grind, you have plenty of new and better options to choose from now.

No Ducts? Your AC Options

  • Ductless mini-split heat pumps can cool whatever part of your home you need, no ductwork required. And since they can also heat your home so efficiently, they’re heavily subsidized in many states.

  • Window ACs have gotten much better in the past five years. If it’s been a long time since you’ve replaced your window unit, you might be pleasantly surprised by the latest improvements.

  • Window heat pumps are an emerging category, building off the success of new window AC designs and the push toward energy-efficient heating. 

  • Portable air conditioners are still fundamentally awful—though even these have begun to improve.

AC Type
Basic Window / Wall AC
Modern Window AC
Window Heat Pump
Ductless Mini Split
Cost per room / zone$200-700$350-700$5,000$2,000 - $10,000
InstallationSimple but awkward, slightly hazardous. Annual.Trickier but controlled, predictable. Annual-ish.Trickier but controlled, predictable. Once.Best left to a professional. Once.
Cooling & dehumidifyingEffective but inconsistentEffective and steadyEffective and steadyEffective and steady
Cooling efficiency (converted, typical)11.4 EER15 EER10 EER13.8 EER
Cost to runMost
NoiseLoud "clunk" on startup, persistent "hum," often "whoosh."Occasional "clunk," persistent but modest "hum" and fan noiseTBD, but should be similar to modern window ACAlmost always very quiet.
WindowsGenerally renders window unusable for the entire summer, unless a custom install.Most models allow you to open the window while they're installed.Current models allow you to open window while installed.Installed in a wall or ceiling, so no effect on windows.
Air filtrationPoorPoorPoorPoor
Heating?Some modelsNoYes, works in most weatherYes, works in all weather
Room sizeUp to 1,000+ sq ftUp to 1,000+ sq ftCurrent models: 300-500 sq ftUp to 1,000+ sq ft

If your home (or a portion of your home) doesn’t have any existing ductwork, mini splits are almost always the easiest and least expensive way to add a built-in air conditioning system, with all of its upsides over room ACs.

  • It’s a one-time installation: You’ll never have to deal with the seasonal burden of window ACs or portable ACs again.

  • They’re much quieter: The loudest part of the system sits at least a few feet away from your house rather than 6 inches from the window (or inside the room). 

  • They’re more comfortable: Mini splits can adjust their power levels to match the heat, holding a steady temperature all day. Most window units cycle between “cold and loud” and “hot and muggy.”

  • They use less energy: Ductless mini splits tend to have significantly higher efficiency ratings than other types of ACs, including cheap window ACs or portable units.

  • They can heat your home, too: Yes, even during the winter, using a lot less energy than your existing heater, and often with better comfort, too. It’s not always the most practical thing to rely entirely on mini splits for heating, but it’s always possible. Either way, they have enormous benefits for heating in mildly cold weather.

What could get in the way of a mini split installation?

  • Costs: Prices vary wildly, but based on real-world quotes made through the EnergySage Marketplace, every room or “zone” costs about $5,000 with installation. That’s at least 10x the cost of a window or wheelie AC. Mini splits save some energy, but it’s nowhere near enough to offset those extra upfront costs, and there’s no proof we’ve seen that mini splits last much longer than window units.

  • For renters: A ductless mini split system is a major and permanent home upgrade. If you want one, you must own your home—or talk your landlord into it. (If the environmental upsides don’t change their minds, maybe the significant rebates and incentives will—though they’ll probably be able to charge higher rent.) 

  • Property layout: If you own a condo in a big apartment building, ductless installation isn’t always simple. (Townhouses and small multi-family buildings should be easy, though.)

If mini splits aren’t in the cards for your house, we still have some good news: After barely changing for most of the past century, window ACs got much better in the past five years.

A handful of well-reviewed window units now use a high-performance inverter-driven compressor—the same tech as ductless mini splits. Since inverter ACs can turn themselves down rather than off once the room cools off, the temperature (and humidity) stay much steadier, and you won’t hear the compressor’s obnoxious “ka-chunk” startup sound as often.

Some new inverter models come in radically different shapes that can make them much more comfortable to live with. 

The Midea U-Shaped AC is the best-known: Instead of the typical rectangular box you have to sandwich between the window sill and sash, the Midea has a gap in the middle so you can completely shut your window between the indoor and outdoor portions. That separation keeps it much quieter indoors. (While you may not have heard of Midea, they’re one of the world’s largest AC and heat pump manufacturers.) 

A couple of other window models come in a saddle-style design, like an upside-down version of the U-shaped design: The indoor and outdoor sides are largely separate, except for a small “bridge” that helps the chassis sit across the window. They’re just flipped upside down.

We’re even starting to see some saddle-style window heat pumps. Gradient, a startup, worked with the New York City Housing Authority to install several dozen of their window heat pumps ahead of winter 2023. The catch? They can be nearly as expensive as installing a mini split and may not be as quiet or energy efficient.

All of these new window units only work in windows that open vertically (or sometimes through a wall). We aren’t aware of upgraded window units that natively fit casement or horizontal slider windows, at least not without a jerry-rigged custom framing.

If you can’t get a window unit that will work, you might need to settle for a portable wheelie unit. Even these ACs aren’t as awful as they used to be. Some brands sell inverter-based models, and some have a 2-in-1 hose that handles both the air intake and heat exhaust through a single tube without depressurizing your house. It’s still a thermodynamically sketchy design that you should only use if you’re out of other options. But it’s way better than no AC at all.

One of the best ways to get a good deal on a major home upgrade—like a ductless mini split system—is to get multiple quotes. The EnergySage Marketplace makes that part easy. When you sign up (at no cost), we'll share some details of your project (but not your contact info!) with our network of vetted, experienced contractors.

We'll also connect you with an EnergySage Energy Advisor—one of our in-house heat pump experts who can help guide you through the installation process.

And don't forget: When mini splits run off of renewable, zero-emissions electricity from solar panels, they're even better for the environment and can even eliminate your heating and cooling bills entirely. The EnergySage Marketplace can also help you find a top-quality solar installer in your area.

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