best window – WIRED’s testing found standout window AC options for different priorities—low cost and useful indicators from an LG model, high-end features from Friedrich, and cooling-plus-backup power from EcoFlow and Zero Breeze. The best pick depends less on BTU alone and
A heat wave doesn’t wait for perfect planning. By the time the first hot day hits, the question turns blunt: do you want a window unit that just cools—or one that keeps working when life gets messy, like a power outage or limited access to outlets?
In WIRED’s window air conditioner testing. the lineup reads like a choose-your-own scenario: an affordable LG option built for large-room cooling. a premium Friedrich model that adds security and filtration. and portable-style window ACs from EcoFlow and Zero Breeze that aim to solve one of the hardest summer problems—staying powered when the grid isn’t cooperating.
LG’s 12,000 BTU model costs $379, but it’s not trying to hide its compromises. Weighing 90 pounds, it needs professional installation with a bracket. During testing, its 60-decibel operation landed in the middle of the pack on noise. Reviewer Lisa Wood Shapiro said it blends into a room well with its white-on-white design. and that the filter replacement indicator light is useful. The app was laggy and difficult to use during her testing, though a remote is included.
Friedrich’s Kuhl air conditioner is the expensive outlier at $1,228—and it also brings the physical heft. Among the heaviest units tested. the reason is a metal chassis designed to provide easy maintenance access and deter first-floor break-ins. This model supports adding a custom Friedrich FreshAire MERV 13 filter to clean the air as it cools. Its screen is easy to read, and it includes a remote. There’s also an app that lets you schedule the unit’s use over the course of the week. but connection with the smart app was described as “a little janky. ” and it paired only with 2.4 GHz signals.
If your main fear is losing power before summer fully arrives, EcoFlow Wave 2 is built around flexibility. Tested at $1,299, the EcoFlow Wave 2 is usually available for much less. Wood Shapiro tested the newest model. while WIRED senior editor Julian Chokkattu previously tested the EcoFlow Wave 1 for more than a year in his wife’s office. He preferred Wave 2 because it’s both lighter and more cost-friendly, with a higher 5,100 BTU rating (up from 4,000). A heating mode rated at 6,100 BTU means it can be used in winter to warm up.
The company says it’s best for rooms up to 107 square feet. but it comes with a practical trade: you need to place it near a window to connect one of the included ducts that vents hot exhaust from the back of the unit out of the room. EcoFlow’s big promise is alternate power. You can run it from a standard AC outlet. or keep it going with an add-on battery when you don’t have access to electricity—or hook it up to solar panels.
Zero Breeze takes a different tack—lighter weight first, battery life second. The Zero Breeze Mark II is priced at $999 and has 2. 300 BTU. which means it won’t deliver the same cooling power as the EcoFlow Wave. It weighs just 17 pounds, and the bundle includes a battery that brings the whole setup to about 30 pounds. With that battery, it can provide four hours of use without needing to be near a wall outlet.
Both the Mark II and the EcoFlow require vent pipes to direct exhaust away and direct cool air to a specific area. But there’s a key difference: unlike the EcoFlow, the Zero Breeze can’t charge the battery and use the AC at the same time.
The Mark III steps up the capacity and expands the battery setup, but it also gets heavier and more expensive. At $1,399, the Mark III is larger than the Mark II and “quite a bit heavier,” now 22 pounds. Add the 1,022-Wh battery pack and you’ll carry another 14 pounds. That extra weight buys more independence from power outlets.
WIRED reviewer Chris Null notes the Mark III introduces a new capability: batteries can now be stacked and charged in sequence, each daisy-chained to the next. The advantage is more practical charging flexibility, though it comes with a warning sign—each battery costs $600+.
The Mark III batteries also include extra outputs for other devices: one USB-C port. one USB-A port. and a 12-volt DC socket. The Mark II battery had all of the above plus a second USB-A port. and there’s “no word on why this was removed.” Even with the higher price and heft. the write-up describes the Mark III as a bigger. punchier unit by most standards and a worthwhile buy for outdoors enthusiasts.
The pressure point across all these options is simple: they’re not competing only on BTU. One unit’s usability hinges on app performance and noise levels. another on security and filtration. and the others on how honestly they handle exhaust. outlets. and the real-world problem of keeping cooling going when power isn’t guaranteed.
The takeaway from the guide’s FAQ is just as grounded. When sizing an air conditioner. BTU matters: BTUs per hour measure how much heat the compressor can remove from a room. The BTU rating also helps prevent oversizing. which can cool too quickly without properly dehumidifying. potentially leading to mold formation in the room and within the device.
To find the right power, the guide says to measure the room by multiplying length and width. The U.S. Department of Energy recommends a minimum of 20 BTUs for every square foot. but it also assumes optimal conditions and good efficiency. For a 150-square-foot room. more typical recommendations are to opt for a 5. 000 BTU AC unit. while especially sunny. high-ceilinged. or poorly insulated rooms may need a 6. 000 to 7. 000 BTU unit. When in doubt. it suggests using a BTU calculator. including a complex whole-house BTU calculator that takes into account building layout and construction. plus location and climate. or a simpler “fast and dirty” rule-of-thumb calculator.
Energy efficiency is measured using the combined energy-efficiency ratio (CEER) rating. which the guide says is one of the best ways to check how much you’ll pay in electricity over time. CEER ratings are usually between 9 and 15, with higher numbers generally meaning lower cost. The guide cautions that a cheap window AC unit can save money upfront but cost more later.
Installation and local rules still matter. Some cities, like New York, require installing brackets to support your window AC. A simple bracket can help, but the guide warns it hasn’t tried one out. Depending on the window type and AC model. you may need a hardware store run for plywood to make sure the window sill sits flat. The guide also recommends getting a friend to help because these units can be heavy and difficult to hold. and dropping one out the window is the last outcome anyone needs.
Before buying, it advises measuring the window and reading the supported window types and sizes for the AC unit you want. Gaps should be sealed as best as possible using the included foam, with the option to buy more if needed.
window air conditioner LG 12 000 BTU Friedrich Kuhl EcoFlow Wave 2 Zero Breeze Mark II Zero Breeze Mark III BTU sizing CEER Energy Star MERV 13 battery AC