Guide and picks
What a whole-house fan costs to run
There is no certification program for this category, so we computed the cost from the manufacturer's own published figures per speed.
By Sawyer V. · Published
The short answer
On low, the mid-size unit draws 73.9 W for 2,361 CFM — about 11¢ for an eight-hour night at 18.34¢/kWh, or $9.76 for a whole summer. On high it is 408 W, about 60¢ a night. Running low is three times more efficient per unit of air — 31.9 CFM per watt against 10.5.
Fan & Frost earns a commission when you buy through our links, at no cost to you. It never changes a ranking, and we say so when the right answer is the cheaper unit or nothing at all. Full disclosure · How we pick.
At a glance
The picks, ranked
Tap any row to jump to the full reasoning. Prices are live from Amazon where we have them, and read “check price” where we don’t — never a number we cannot verify today.
| # | Product | Best for | Price |
|---|---|---|---|
| 1 | Cheapest to run QuietCool Stealth Pro X Whole House Fan, 4,280 CFM 2,361 CFM on 73.9 W low — 31.9 CFM per watt, the best efficacy figure on this site. | An average house of roughly 1,400 to 2,100 sq ft | |
| 2 | Smaller house, same low-speed cost QuietCool Stealth Pro X Whole House Fan, 3,159 CFM 1,980 CFM on 74.6 W low — essentially the same draw as the larger fan, for less air. | A house of roughly 1,000 to 1,600 sq ft | |
| 3 | Largest, and the one where high costs QuietCool Stealth Pro X Whole House Fan, 6,996 CFM 4,308 CFM on 166 W low — and 6,996 CFM on 725 W high, the biggest draw here by far. | A house of roughly 2,300 to 3,500 sq ft | |
| — | What it is competing with Midea Window Air Conditioner, 6,000 BTU CEER 16 and 281.3 kWh a year — the cheapest certified cooling, and still far more than a whole-house fan. | Nights when outdoor air is not cooler than indoor |
This category has no certification program, so nobody publishes a running cost. The manufacturers do publish CFM and watts per speed, which is enough to compute one.
The table
Every speed, costed
Figures below are the manufacturer’s published CFM and watts per speed, with our arithmetic applied at 18.34¢/kWh.
| Fan and speed | CFM | Watts | CFM/W | 8-hour night | 90 nights |
|---|---|---|---|---|---|
| 4.8X low | 2,361 | 73.9 W | 31.9 | 11¢ | $9.76 |
| 3.3X low | 1,980 | 74.6 W | 26.5 | 11¢ | $9.85 |
| 7.0X low | 4,308 | 166 W | 26.0 | 24¢ | $22 |
| 4.8X medium | 3,500 | 225 W | 15.6 | 33¢ | $30 |
| 3.3X high | 3,159 | 264 W | 12.0 | 39¢ | $35 |
| 7.0X medium | 5,448 | 319 W | 17.1 | 47¢ | $42 |
| 4.8X high | 4,280 | 408 W | 10.5 | 60¢ | $54 |
| 7.0X high | 6,996 | 725 W | 9.7 | $1.06 | $96 |
The spread from cheapest to dearest is $9.76 against $96 across a summer — roughly a tenfold difference, from the same category of machine.
The finding
Low speed is three times more efficient
The single most useful number here: the same fan runs at 31.9 CFM per watt on low and 10.5 on high.
That is not a small tuning difference. Tripling your air-per-watt by moving one switch is a larger effect than anything else in this category, including which model you bought.
The reason is fan physics: power rises much faster than airflow as speed increases. Doubling the air takes far more than double the power, so a large fan turning slowly always beats a small one turning fast.
The same relationship explains why a ceiling fan on low draws 1.1 W while its high speed draws ten or twenty times that, and why 71.8% of certified multi-speed bathroom fans are more efficient below full speed.
Comparison
Against everything else on this site
| Option | Draw | One night | What it cools |
|---|---|---|---|
| Ceiling fan, low | 1.1 W | 0.2¢ | One person |
| Whole-house fan, low | 73.9 W | 11¢ | The whole house |
| Window fan, low | 22 W | 3.2¢ | One room |
| Evaporative cooler | 250 W | 37¢ | One space, dry climates |
| Whole-house fan, high | 408 W | 60¢ | The whole house, fast |
| Portable air conditioner | 1,300 W | $1.91 | One room |
Read the last column. A whole-house fan on low costs about three times a single-room window fan and cools the entire house, which makes it the cheapest per square foot of anything here.
It is also the most conditional. Everything else in that table works regardless of the weather; a whole-house fan only works when the outdoor air is cooler than the indoor air.
The caveat
These are manufacturer figures, not certified ones
We say this on every whole-house and attic fan page and it belongs on a cost page particularly.
The ENERGY STAR Certified Ventilating Fans dataset holds 1,140 records in four types — 973 bathroom and utility fans, 92 range hoods, 73 single-port in-line fans and 2 multi-port. There are zero whole-house fans and zero attic fans.
What that means for the numbers above:
- The CFM and watt figures are the manufacturer’s own. Not independently verified at a defined static pressure.
- The CFM per watt column is our arithmetic, computed from those figures rather than repeated from marketing.
- The cost columns are simple multiplication at 18.34¢/kWh. Substitute your own rate.
- Real airflow depends on your attic venting. An under-vented attic throttles the fan, so actual CFM may be lower and actual efficacy worse.
This one is not a DIY job
Attic venting is what determines whether you get the published airflow. A whole-house fan pushes thousands of CFM into the attic and that air must leave. Insufficient venting pressurizes the space, throttles the fan, and can push air back into the house through ceiling penetrations.
Manufacturers specify a minimum net free venting area per model. Meeting it frequently means adding vents.
Combustion safety. Depressurising a house with an open-flued gas appliance, water heater or fireplace can backdraft combustion gases into living space. That needs professional assessment before installation.
Installation involves a large ceiling opening, framing, electrical work and an insulated damper. It belongs to a qualified installer.
Say the unwelcome thing
Do not run a whole-house fan on high all night.
It is the setting people reach for because it feels like getting value from the machine, and it is the most expensive way to use it by a factor of three.
The same fan delivers 31.9 CFM per watt on low and 10.5 on high. On the largest unit here that is 24¢ a night against $1.06 — and across ninety nights, $22 against $96.
Fan power rises much faster than airflow with speed, so a big fan turning slowly always beats the same fan turning fast.
Use high for a fast purge at dusk when the crossover happens, then drop to low for the night. On a 2,361 CFM low speed that is 11¢ for the whole night — and it is cooling the whole house.
In full
Every pick, and what is wrong with it
Published specifications only, each linked to the page it came from. Where a manufacturer publishes nothing, the row says so — we do not fill blanks in.
1. Cheapest to run
QuietCool Stealth Pro X Whole House Fan, 4,280 CFM
QuietCool · model QC STL PRO-4.8X
2,361 CFM on 73.9 W low — 31.9 CFM per watt, the best efficacy figure on this site.
The best air-per-watt figure anywhere in this catalog, and it comes from running it gently.
73.9 W on low is 11¢ for an eight-hour night and about $9.76 across ninety nights at 18.34¢/kWh.
31.9 CFM per watt — nearly double the best certified bathroom fan at 16.7 and six times the best in-line duct fan at 5.2, because it pushes into an attic against almost no static pressure.
ECM motor, three speeds, 15-year warranty. Running it on low is not a compromise; it is the whole economic case.
What’s wrong with it
408 W on high, and no noise figure is published in any form.
Running cost — QC STL PRO-4.8X
| Nameplate power | 73.9 W – 408 W | manufacturer's published figure |
|---|---|---|
| Energy, 8-hour night | 3.26 kWh | 408 ÷ 1000 × 8 |
| Cost per hour | 7.5¢ | at 18.34¢/kWh |
| Cost per 8-hour night | 60¢ | on the highest speed |
| Cost per 30 nights | $18 | 97.9 kWh |
| Same month, lowest speed | $3.25 | at 73.9 W |
Rate: 18.34¢/kWh, the US average residential price for June 2026 (EIA Electric Power Monthly, Table 5.3). Yours will differ — swap it in: (watts ÷ 1000) × hours × your rate.
| Air delivery, high | 4,280 CFM |
|---|---|
| Air delivery, medium | 3,500 CFM |
| Air delivery, low | 2,361 CFM |
| Power, high | 408 W |
| Power, medium | 225 W |
| Power, low | 73.9 W |
| Coverage claim | 1,427 - 2,140 sq ft |
| Motor | ECM |
| Warranty | 15 years |
| Noise | Not published as sones or dBA |
| ENERGY STAR | No program exists for whole-house fans |
Every figure above is from QuietCool Stealth Pro X specification sheet, QC STL PRO-4.8. Blanks are shown as “not published” rather than filled in.
2. Smaller house, same low-speed cost
QuietCool Stealth Pro X Whole House Fan, 3,159 CFM
QuietCool · model QC STL PRO-3.3X
1,980 CFM on 74.6 W low — essentially the same draw as the larger fan, for less air.
A genuinely counter-intuitive result worth knowing before you size down to save money.
74.6 W on low against 73.9 W for the larger fan. The draw is essentially identical; the smaller fan simply moves 1,980 CFM instead of 2,361.
That is 26.5 CFM per watt against 31.9. A larger blade turning slowly beats a smaller one working harder, which is the same physics that makes big ceiling fans efficient.
264 W on high for 3,159 CFM, ECM motor, 15-year warranty. Buy this for the smaller ceiling opening, not for lower running cost.
What’s wrong with it
26.5 CFM per watt against 31.9 for the bigger unit, so it is the less efficient machine on low.
Running cost — QC STL PRO-3.3X
| Nameplate power | 74.6 W – 264 W | manufacturer's published figure |
|---|---|---|
| Energy, 8-hour night | 2.11 kWh | 264 ÷ 1000 × 8 |
| Cost per hour | 4.8¢ | at 18.34¢/kWh |
| Cost per 8-hour night | 39¢ | on the highest speed |
| Cost per 30 nights | $12 | 63.4 kWh |
| Same month, lowest speed | $3.28 | at 74.6 W |
Rate: 18.34¢/kWh, the US average residential price for June 2026 (EIA Electric Power Monthly, Table 5.3). Yours will differ — swap it in: (watts ÷ 1000) × hours × your rate.
| Air delivery, high | 3,159 CFM |
|---|---|
| Air delivery, low | 1,980 CFM |
| Power, high | 264 W |
| Power, low | 74.6 W |
| Coverage claim | 1,053 - 1,580 sq ft |
| Motor | ECM |
| Warranty | 15 years |
| Noise | Not published as sones or dBA |
| ENERGY STAR | No program exists for whole-house fans |
Every figure above is from QuietCool Stealth Pro X specification sheet, QC STL PRO-3.3. Blanks are shown as “not published” rather than filled in.
3. Largest, and the one where high costs
QuietCool Stealth Pro X Whole House Fan, 6,996 CFM
QuietCool · model QC STL PRO-7.0X
4,308 CFM on 166 W low — and 6,996 CFM on 725 W high, the biggest draw here by far.
The unit where the speed choice makes the most difference to the bill, in both directions.
166 W on low for 4,308 CFM — 24¢ for a night, at 26.0 CFM per watt.
725 W on high for 6,996 CFM is $1.06 a night at 9.7 CFM per watt — the worst efficacy in this roundup, and nearly ten times the low-speed cost.
Use high for a fast purge at dusk and drop to low for the night. That single habit is worth more than the difference between any two models here.
What’s wrong with it
725 W on high is more than a small evaporative cooler, at 9.7 CFM per watt.
Running cost — QC STL PRO-7.0X
| Nameplate power | 166 W – 725 W | manufacturer's published figure |
|---|---|---|
| Energy, 8-hour night | 5.80 kWh | 725 ÷ 1000 × 8 |
| Cost per hour | 13¢ | at 18.34¢/kWh |
| Cost per 8-hour night | $1.06 | on the highest speed |
| Cost per 30 nights | $32 | 174.0 kWh |
| Same month, lowest speed | $7.31 | at 166 W |
Rate: 18.34¢/kWh, the US average residential price for June 2026 (EIA Electric Power Monthly, Table 5.3). Yours will differ — swap it in: (watts ÷ 1000) × hours × your rate.
| Air delivery, high | 6,996 CFM |
|---|---|
| Air delivery, medium | 5,448 CFM |
| Air delivery, low | 4,308 CFM |
| Power, high | 725 W |
| Power, medium | 319 W |
| Power, low | 166 W |
| Coverage claim | 2,332 - 3,498 sq ft |
| Motor | ECM |
| Warranty | 15 years |
| Noise | Not published as sones or dBA |
| ENERGY STAR | No program exists for whole-house fans |
Every figure above is from QuietCool Stealth Pro X specification sheet, QC STL PRO-7.0. Blanks are shown as “not published” rather than filled in.
Skip this one
Midea Window Air Conditioner, 6,000 BTU
Midea · model MAW06S1KWT-A
CEER 16 and 281.3 kWh a year — the cheapest certified cooling, and still far more than a whole-house fan.
Included for scale, and marked skip because it is a complement rather than an alternative.
281.3 kWh a year is about $52 for a season at 18.34¢/kWh— and that is the cheapest certified room air conditioner at any capacity.
A whole-house fan on low across ninety nights is about $9.76. Roughly a quarter, for a machine cooling the whole house rather than one room.
The catch is conditional: the fan only works when outdoor air is genuinely cooler than indoor air. On a hot humid night it does nothing useful, and that is when the compressor earns its keep.
What’s wrong with it
A whole-house fan only works when the outdoor air is worth importing. This works always.
Running cost — MAW06S1KWT-A
| Annual energy use | 281.3 kWh | ENERGY STAR certified figure |
|---|---|---|
| Annual cost | $52 | 281.3 × 18.34¢/kWh |
| Per cooling month | $13 | spread over a four-month season |
The annual figure is the certified value from the ENERGY STAR Certified Room Air Conditioners dataset, which models a standard cooling season rather than your actual summer. It is more useful than a nameplate wattage here, because a variable-speed compressor spends most of its life well below nameplate.
Rate: 18.34¢/kWh, the US average residential price for June 2026 (EIA Electric Power Monthly, Table 5.3). Yours will differ — swap it in: (watts ÷ 1000) × hours × your rate.
| Cooling capacity | 6,000 BTU/h |
|---|---|
| CEER | 16 |
| Annual energy use | 281.3 kWh/yr |
| vs federal standard | 45% less energy |
| Dimensions | 12.1 H x 16.0 W x 13.3 D in |
| Weight | 31.6 lb |
| Installation | Does not straddle the windowsill |
| Support bracket | Not required |
| Compressor | Variable speed |
| Refrigerant | R-32 |
| ENERGY STAR | Certified, and on the Most Efficient list |
Every figure above is from ENERGY STAR Certified Room Air Conditioners dataset. Blanks are shown as “not published” rather than filled in.
We are not linking a buy button for this one. If you want to look at it anyway, it is easy enough to find — but we would rather send you to something that fits your room.
Questions people actually ask
Frequently asked
How much does it cost to run a whole house fan?
On low, about 11¢ for an eight-hour night at 18.34¢/kWh — roughly $9.76 across a whole summer. On high the same fan draws 408 W, about 60¢ a night.
Should I run a whole house fan on high or low?
Low, almost always. The same fan delivers 31.9 CFM per watt on low and 10.5 on high — three times the air per watt. Use high for a fast purge at dusk, then drop to low for the night.
Is a whole house fan cheaper than air conditioning?
Substantially, where it works. A whole-house fan on low across ninety nights is about $9.76, against $52 for a season from the cheapest certified room air conditioner — which cools one room rather than the house.
Are whole house fan efficiency figures certified?
No. The certified ventilating fans dataset holds 1,140 records across bathroom and utility fans, range hoods and in-line fans, and zero whole-house or attic fans. The CFM and watt figures are the manufacturer's own; the CFM per watt is our arithmetic on them.
Why is the bigger fan more efficient on low?
A larger blade turning slowly moves more air per watt than a smaller one working harder. The 4.8X draws 73.9 W on low and the smaller 3.3X draws 74.6 W — essentially the same power for 19% less air.
Will I actually get the published airflow?
Only if the attic can exhaust it. A whole-house fan pushes thousands of CFM into the attic and that air has to leave; insufficient venting throttles the fan, so real airflow may be lower and real efficacy worse than the published figures. Whole-house fans, ranked.
Sources
Where these numbers came from
- QuietCool Stealth Pro X specification sheet, QC STL PRO-4.8 — CFM and watts per speed
- QuietCool Stealth Pro X specification sheet, QC STL PRO-7.0
- QuietCool Stealth Pro X specification sheet, QC STL PRO-3.3
- ENERGY STAR Certified Ventilating Fans dataset — the four certified unit types, none of which is a whole-house fan
- EIA Electric Power Monthly, Table 5.3 — average residential electricity price
Read next
Where to go from here
Back to Whole-House Airflow, or read how we pick.