When I started looking into potential new window air conditioner recommendations for 2024, not much was actually new—just larger versions of ACs I’d already tested.
This is obviously a good thing for people with larger rooms. But it also got me thinking.
Conventional wisdom with traditional (non-inverter) window ACs holds that too-small units underperform. An oversize AC might cool the room down faster, but it can also waste a lot of energy and leave the air feeling cold, damp, and clammy.
Now that the best window air conditioners mostly use inverter compressors, which vary their speed and power output, I wondered if it might be advantageous to get an oversize unit for the space. You’d have low energy consumption most of the time and some oomph when you really want the extra British thermal units (Btu) to crank out a powerful icy blast.
But after measuring the performance of two sizes of ACs (in both traditional and inverter formats, in a single room with consistent starting conditions this summer), I can tell you: Oversizing your AC is still a terrible idea.
