Model
Keystone KSTAW08INV-HC
Rank #115 means 114 of the 404 room air conditioner models we track cost less to run each year; the 71st efficiency percentile means it uses less energy for its size than 71% of those models.
What does the Keystone KSTAW08INV-HC cost to run per year?
At $77 a year to run, the Keystone KSTAW08INV-HC runs cheaper than most models in its class, ranking #115 of 404 room air conditioner models we track. It uses 48% less energy than the U.S. federal standard model in its class, which would cost about $148/yr to run, a saving of roughly $71 a year. Once capacity is factored in, its 71th efficiency percentile puts it ahead of most peers in its class. At a CEER of 14.5, 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 Friedrich KCVS08B10A at $76/yr runs a little cheaper and the Midea MAW08HV1CWT at $77/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 KSTAW08INV-HC's $77/yr adds up to roughly $770 in electricity alone, before purchase price or repairs.
Also sold as: Midea MAW08HV1CWT, Midea MWAUQB-08HRFN8-BCL0.
By the numbers
The Keystone KSTAW08INV-HC 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 $77/yr, here is what the Keystone KSTAW08INV-HC 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 KSTAW08INV-HC costs about $770. That is roughly $710 less than a standard model in its class, which would run closer to $1480 over the same ten years.
How the Keystone KSTAW08INV-HC compares
The room air conditioner class we track runs from $51 to $389 a year. At $77/yr, it runs about $22 a year cheaper than the class median of $99, and it is about $26 a year more than the cheapest room air conditioner to run at $51. Against the US federal standard model for its class at about $148/yr, the Keystone KSTAW08INV-HC uses 48% less energy.
What drives its running cost
At 8000 BTU/hr, the Keystone KSTAW08INV-HC is a small room air conditioner for its class, which spans 5000 to 34100 BTU/hr with a median of 10100 BTU/hr, and smaller room air conditioner models generally cost less to run for the same job, all else being equal. Beyond size, its CEER of 14.5, below 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). CEER captures cooling output per watt, including standby power; a higher CEER means less electricity for the same BTU of cooling.
- BTU cooling capacity. A higher-BTU unit is sized for a bigger room and generally uses more electricity per hour of operation than a smaller unit, regardless of efficiency.
- Thermostat and mode usage. Running on a fixed low temperature around the clock uses far more energy than using a thermostat setting, eco mode, or a timer to match cooling to when the room is actually occupied.
Common questions
Is the Keystone KSTAW08INV-HC cheap to run?
Yes, relatively. At $77 a year it ranks #115 of 404 room air conditioner models we track, in the cheaper part of its class to run.
How much does the Keystone KSTAW08INV-HC cost per month?
Roughly $6.4/mo, spreading the $77/yr estimate evenly across twelve months at $0.1856/kWh. Actual monthly bills swing with your rate and usage pattern.
How is this running-cost figure calculated?
We take the model's published annual energy use of 414 kWh from ENERGY STAR and multiply it by the US average residential electricity rate of $0.1856/kWh, giving about $77 a year. It is an electricity-only estimate and does not include purchase price, water, or installation.
How efficient is the Keystone KSTAW08INV-HC for its size?
71st percentile once size is factored in, a fairly typical result for the class.
Cheaper to run in the same class
Source
ES_1055302_KSTAW08INV-HC_040720230730708_5821191View certified room air conditioner listingsENERGY STAR data as of July 2026Keystone and KSTAW08INV-HC 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.