The three formats look like they do the same job. They don't, quite. Here's the honest breakdown.
Window units — the default, for good reason
Best for: standard double-hung windows, most NYC apartments, most bedrooms and living rooms.
A window AC is the most efficient cooling-per-dollar you can buy. The hot side hangs outside, the cold side blows inside, and the line between them is the window sash. Almost nothing is wasted.
Pros:
- Cheapest to buy.
- Best efficiency (CEER) of the three formats.
- Easy to remove and reinstall season to season.
Cons:
- You lose the use of that window.
- They block some light and the view.
- Improperly installed, they can fall — which is exactly why NYC building code and most landlords require a bracket (we cover that in our bracket article).
- Some buildings simply don't allow them on certain floors.
If your room has a double-hung window and your landlord allows it, this is almost certainly your answer.
Through-the-wall (wallfit) — for buildings that built for it
Best for: apartments with an existing AC sleeve in the wall, or buildings that built sleeves at construction.
A through-the-wall unit slides into a sleeve in the wall instead of a window. You see it from inside (and from outside), but it doesn't block a window.
Pros:
- Keeps your window free.
- Permanent and secure — no annual removal, no falling-out risk.
- Tighter seal than a window unit, less air leak around the frame.
Cons:
- You need a sleeve. Cutting one yourself is a project — drywall, brick or block, electrical, weatherproofing. Most renters can't.
- The unit dimensions have to match the sleeve, so you have less model choice.
- Removal/replacement is a service call, not a weekend job.
If your building has sleeves, this is usually the better long-term choice. If it doesn't, this is a major capital project, not a purchase decision.
Portable — when the other two won't work
Best for: sliding windows, casement windows, basement spaces, or buildings that don't allow window units.
A portable AC sits on the floor and vents hot air out through a hose you stick out a window. You're not mounting anything; you're standing it next to a window like a tall trash can.
Pros:
- No installation, no brackets, no window-shape restrictions.
- Movable room to room.
- Allowed where window units aren't.
Cons:
- Significantly less efficient. You're cooling air, then the unit re-warms part of it through internal heat loss. A 12,000 BTU portable doesn't cool like a 12,000 BTU window unit.
- Bigger and louder. The compressor sits inside the room with you.
- Takes up floor space.
- The exhaust hose is often the weak link — if it kinks or leaks, half your efficiency goes with it.
Portables are honest about being the compromise. If you can put in a window unit, do that instead. If you can't, a portable is better than a fan.
Quick decision tree
- Does your building allow a window AC, and do you have a double-hung window in the right room? Get a window unit.
- Does the apartment have a wall sleeve? Get a through-the-wall unit sized to the sleeve.
- Neither? Get a portable, ideally one with a dual-hose exhaust.
What we install
We carry all three. Window units make up the bulk of what we sell because they make sense for most NYC apartments — but if your building has sleeves, we'll size a through-the-wall correctly, and if you need a portable, we'll set it up for you so the exhaust seal isn't leaking conditioned air all summer.