Model
Keystone KSTAW10INV
Rank #143 means 142 of the 404 room air conditioner models we track cost less to run each year; the 65th efficiency percentile means it uses less energy for its size than 65% of those models.
What does the Keystone KSTAW10INV cost to run per year?
Among the 404 room air conditioner models we track, the Keystone KSTAW10INV sits in the below-average-cost group, rank #143, at roughly $93 a year. It uses 38% less energy than the U.S. federal standard model in its class, which would cost about $150/yr to run, a saving of roughly $57 a year. Capacity-normalized, it ranks ahead of 65% of room air conditioner models we track, a reasonably strong result for the class. At a CEER of 15, its combined energy efficiency ratio is the single figure that best explains how it earns its running-cost number.
Immediately around it on the leaderboard, the Keystone KSTAW101WA at $93/yr runs a little cheaper and the Ktaxon KXTIW-10CRD1 at $93/yr runs a little more, a sense of how tightly models are packed at this point in the ranking. A room air conditioner typically stays in service for somewhere around 10 years; over that span, the Keystone KSTAW10INV's $93/yr adds up to roughly $930 in electricity alone, before purchase price or repairs.
Also sold as: Black+Decker BD10NWES.
By the numbers
The Keystone KSTAW10INV normalized against its whole class, so each figure means something.
What it costs you over time
Running cost is an every-year number, so it compounds. At $93/yr, here is what the Keystone KSTAW10INV adds up to before purchase price, water, or repairs enter the math.
Left running for a decade at today's US average rate, the Keystone KSTAW10INV costs about $930. That is roughly $570 less than a standard model in its class, which would run closer to $1500 over the same ten years.
How the Keystone KSTAW10INV compares
The room air conditioner class we track runs from $51 to $389 a year. At $93/yr, it runs about $6 a year cheaper than the class median of $99, and it is about $42 a year more than the cheapest room air conditioner to run at $51. Against the US federal standard model for its class at about $150/yr, the Keystone KSTAW10INV uses 38% less energy.
What drives its running cost
At 10000 BTU/hr, the Keystone KSTAW10INV is a small room air conditioner for its class, which spans 5000 to 34100 BTU/hr with a median of 10100 BTU/hr, at the small end of the class, capacity itself is doing a lot of the work to keep that figure down, separate from how efficient the unit actually is. Beyond size, its CEER of 15, above the class median of 15, is the class's own efficiency yardstick, combined energy efficiency ratio, and it is what separates two similarly sized models with different running costs.
- Combined Energy Efficiency Ratio (CEER). Two units with the same BTU rating can post very different running costs, and CEER is the figure that explains most of that gap.
- BTU cooling capacity. BTU rating scales with room size, and it is usually the first driver of an air conditioner's running cost, ahead of its CEER figure.
- Thermostat and mode usage. How the unit is actually operated, thermostat cycling versus a fixed setting, moves real electricity use more than the rated BTU or CEER figure alone.
Common questions
Is the Keystone KSTAW10INV cheap to run?
Yes. Its $93/yr running cost puts it at rank #143 of 404, below what most room air conditioner models we track cost to run.
How much does the Keystone KSTAW10INV cost per month?
About $7.73 a month, which is the $93 annual estimate spread across twelve months at the US average rate of $0.1856/kWh. Your own bill scales with your local electricity rate and how heavily you use it.
How is this running-cost figure calculated?
The formula is annual kWh times price per kWh: 500 kWh from ENERGY STAR times the US average of $0.1856/kWh comes to about $93 a year. It covers electricity only, not the purchase price, water, or installation.
How efficient is the Keystone KSTAW10INV for its size?
65th percentile once size is factored in, a fairly typical result for the class.
Cheaper to run in the same class
| Rank | Model | Cost/yr |
|---|---|---|
| 160 | Keystone KSTAW101WA10000 BTU/hr | $93 |
| 159 | Keplerx KARC10RSVE110000 BTU/hr | $93 |
| 158 | Hykolity ACB-262210000 BTU/hr | $93 |
| 157 | Hykolity ACB-260210000 BTU/hr | $93 |
| 156 | Hisense AWUS1026TW10000 BTU/hr | $93 |
Source
ES_1055302_KSTAW10INV_01292024112932_80198612View certified room air conditioner listingsENERGY STAR data as of July 2026Keystone and KSTAW10INV are used here for identification only and are not endorsements. Figures are computed by WattWise Labs from public ENERGY STAR data, not measured in our own lab.