How energy-efficient is the Keystone 24,000 BTU Inverter Window Air Conditioner?

Its efficiency rating is CEER 13.3, and it is ENERGY STAR certified.

What size room does the Keystone 24,000 BTU Inverter Window Air Conditioner cool?

It is rated to cool a room up to 1,500 sq ft (24,000 BTU · 7 kW).

Do I need a professional to install the Keystone 24,000 BTU Inverter Window Air Conditioner?

No. It is a window unit you can fit yourself, no professional needed. Usually no permit.

Window unitENERGY STAR

Keystone · Model KSTAW242WA

24,000 BTU Inverter Window Air Conditioner

Name: Keystone 24,000 BTU Inverter Window Air Conditioner
Brand: Keystone

A window air conditioner rated at 24,000 BTU for rooms up to 1,500 sq ft. It self-installs in a window.

$730

List price

No live retailer for this exact model right now.

Last listed at Sylvane for $759.99 on Aug 6, 2026. We have not been able to confirm it since.

The closest window unit you can buy today:

LG 23,500 BTU 230/208V DUAL Inverter Smart Wi-Fi Enabled Window Air Conditioner

Performance

Cooling capacity: 24,000 BTU · 7 kW
Heating capacity: Cooling only
Room coverage: up to 1,500 sq ft
Energy Star: Yes
CEER: 13.3
Annual energy (cooling): 1353 kWh

Noise, size & features

Model number: KSTAW242WA
Indoor noise: Not published
Outdoor noise: Not published
Indoor unit: 25.39 x 17.91 x 23.62 in

What is good

Uses R-32 (GWP 675), the low-GWP class new US residential equipment moved to.

What to watch

Its CEER 13.3 is less efficient than 41 of the 47 other window units we list with a published CEER.

Installation & the rules that apply

This is a window unit. No EPA Section 608 technician is needed: the refrigerant circuit is factory-sealed and never opened. A plug-in window unit needs no permit, so the friction is with your building rather than the government. Many HOAs restrict window units on appearance grounds, though an HOA regulating how you mount one stands on much firmer ground than one banning cooling outright. Landlords can set conditions, and the falling hazard is taken seriously: New York City, for instance, requires window units to be supported by brackets or mounting rails, and many building insurers and HOAs now require a bracket regardless of city.

Installation

Self-fit, no pro needed

Refrigerant

R-32

GeneralRenters: get written landlord consent firstReviewed June 2026Often blocks install

Common questions about the Keystone 24,000 BTU Inverter Window Air Conditioner

How much does the Keystone 24,000 BTU Inverter Window Air Conditioner cost to run per year?: About $250 a year. Estimated from ENERGY STAR's published annual energy use at about 750 hours of cooling a year (the DOE test standard) and the US average electricity price of 18.44¢/kWh (U.S. Energy Information Administration, Electric Power Monthly Table 5.6.A (residential average, May 2026)). A standardized figure for comparison; your real cost depends on how much you run it, your local rate and your climate.
How energy-efficient is the Keystone 24,000 BTU Inverter Window Air Conditioner?: Its efficiency rating is CEER 13.3, and it is ENERGY STAR certified.
What size room does the Keystone 24,000 BTU Inverter Window Air Conditioner cool?: It is rated to cool a room up to 1,500 sq ft (24,000 BTU · 7 kW).
Do I need a professional to install the Keystone 24,000 BTU Inverter Window Air Conditioner?: No. It is a window unit you can fit yourself, no professional needed. Usually no permit.