Model
Della 048-TL-W8KI
Rank #51 means 50 of the 404 room air conditioner models we track cost less to run each year; the 85th efficiency percentile means it uses less energy for its size than 85% of those models.
What does the Della 048-TL-W8KI cost to run per year?
The Della 048-TL-W8KI costs about $74 a year to run and sits near the top of the cheapest-to-run leaderboard, rank #51 of 404. It uses 38% less energy than the U.S. federal standard model in its class, which would cost about $120/yr to run, a saving of roughly $46 a year. Once capacity is factored in, it outperforms 85% of the room air conditioner models we track on efficiency, not just on headline running cost. Its CEER of 15 reflects combined energy efficiency ratio, one of the class's core efficiency levers.
Immediately around it on the leaderboard, the Danby DAC080EBIBDB at $74/yr runs a little cheaper and the Element EHWR08BE at $74/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 Della 048-TL-W8KI's $74/yr adds up to roughly $740 in electricity alone, before purchase price or repairs.
Also sold as: Black+Decker BD08NWES.
By the numbers
The Della 048-TL-W8KI 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 $74/yr, here is what the Della 048-TL-W8KI adds up to before purchase price, water, or repairs enter the math.
Left running for a decade at today's US average rate, the Della 048-TL-W8KI costs about $740. That is roughly $460 less than a standard model in its class, which would run closer to $1200 over the same ten years.
How the Della 048-TL-W8KI compares
The room air conditioner class we track runs from $51 to $389 a year. At $74/yr, it runs about $25 a year cheaper than the class median of $99, and it is about $23 a year more than the cheapest room air conditioner to run at $51. Against the US federal standard model for its class at about $120/yr, the Della 048-TL-W8KI uses 38% less energy.
What drives its running cost
At 8000 BTU/hr, the Della 048-TL-W8KI is a small room air conditioner for its class, which spans 5000 to 34100 BTU/hr with a median of 10100 BTU/hr, less capacity to service is usually the first reason a running-cost figure lands on the low side, before efficiency even enters the picture. The CEER of 15 on this model, above the class median of 15, measures combined energy efficiency ratio; it is the number to compare directly against another model's CEER if capacity is similar.
- 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 Della 048-TL-W8KI cheap to run?
Yes, relatively. At $74 a year it ranks #51 of 404 room air conditioner models we track, in the cheaper part of its class to run.
How much does the Della 048-TL-W8KI cost per month?
Roughly $6.19/mo, spreading the $74/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 400 kWh from ENERGY STAR and multiply it by the US average residential electricity rate of $0.1856/kWh, giving about $74 a year. It is an electricity-only estimate and does not include purchase price, water, or installation.
How efficient is the Della 048-TL-W8KI for its size?
85th percentile once size is factored in. That means its size-adjusted efficiency is a real factor in the running-cost figure above; its capacity plays a large role too.
Cheaper to run in the same class
| Rank | Model | Cost/yr |
|---|---|---|
| 56 | Danby DAC080EBIBDB8000 BTU/hr | $74 |
| 55 | Danby DAC080B8IWDB-68000 BTU/hr | $74 |
| 54 | Danby DAC080B7IWDB-68000 BTU/hr | $74 |
| 53 | Comfort Aire RXTS-81A8000 BTU/hr | $74 |
| 52 | Century RXTS-81A8000 BTU/hr | $74 |
Source
ES_1141693_048-TL-W8KI_02292024165059_4724084View certified room air conditioner listingsENERGY STAR data as of July 2026Della and 048-TL-W8KI 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.