Sizing and ventilation
21 whole-house fan statistics (2026)
Compare fan running costs in every state, then check the airflow, power and humidity evidence.
By Best Whole House Fan research teamPublished · Updated
[1] August 2026 residential prices. Power is an example; costs are electricity only.
Key takeaways
The U.S. average residential electricity price was 18.16 cents per kWh in August 2026, according to EIA Table 5.6.A. (U.S. EIA, October 2026).
State residential electricity prices ranged from 12.72 to 47.18 cents per kWh in August 2026, with Nevada lowest and Hawaii highest. (U.S. EIA, October 2026).
HVI sizes whole-house comfort airflow at 3 CFM per square foot of gross home area, including upper stories, with an eight-foot ceiling assumption. (HVI, accessed October 2026).
PNNL recommends at least 4 square feet of open screened-window area per 1,000 CFM for whole-house fan operation. (PNNL, September 2022).
FSEC’s study of one Cocoa Beach, Florida home in summer 1991 found evening indoor temperatures 3–6°F cooler after whole-house fan operation, as reported in 1992. (Florida Solar Energy Center, 1992).
The U.S. EPA advises indoor relative humidity below 60%, ideally between 30% and 50%, in its household mold and moisture guidance. (U.S. EPA, September 2012).
Whole-house fan running costs by state
[1] August 2026 residential average prices. Calculated costs use 500 W for four hours a day over 30 days.
50 states and DC
| State | 2026 price ¢/kWh | Change vs Aug 2025 | 100 W ¢/hour | 500 W ¢/hour | 500 W $/defined month |
|---|---|---|---|---|---|
| Alabama | 16.33 | +0.43% | 1.63 | 8.16 | 9.80 |
| Alaska | 29.41 | +5.83% | 2.94 | 14.71 | 17.65 |
| Arizona | 15.05 | -0.27% | 1.51 | 7.53 | 9.03 |
| Arkansas | 14.37 | +7.80% | 1.44 | 7.18 | 8.62 |
| California | 29.75 | -3.78% | 2.98 | 14.88 | 17.85 |
| Colorado | 17.17 | +5.92% | 1.72 | 8.59 | 10.30 |
| Connecticut | 24.51 | -18.76% | 2.45 | 12.26 | 14.71 |
| Delaware | 18.70 | +10.98% | 1.87 | 9.35 | 11.22 |
| District of Columbia | 25.98 | +12.08% | 2.60 | 12.99 | 15.59 |
| Florida | 14.99 | -2.22% | 1.50 | 7.50 | 8.99 |
| Georgia | 15.90 | +2.25% | 1.59 | 7.95 | 9.54 |
| Hawaii | 47.18 | +22.45% | 4.72 | 23.59 | 28.31 |
| Idaho | 13.37 | +10.68% | 1.34 | 6.68 | 8.02 |
| Illinois | 19.32 | +7.15% | 1.93 | 9.66 | 11.59 |
| Indiana | 17.02 | +5.00% | 1.70 | 8.51 | 10.21 |
| Iowa | 17.06 | +10.21% | 1.71 | 8.53 | 10.24 |
| Kansas | 15.47 | +5.60% | 1.55 | 7.74 | 9.28 |
| Kentucky | 13.80 | +5.34% | 1.38 | 6.90 | 8.28 |
| Louisiana | 12.87 | +2.55% | 1.29 | 6.43 | 7.72 |
| Maine | 32.11 | +14.11% | 3.21 | 16.05 | 19.27 |
| Maryland | 21.40 | +7.59% | 2.14 | 10.70 | 12.84 |
| Massachusetts | 30.48 | -0.23% | 3.05 | 15.24 | 18.29 |
| Michigan | 22.99 | +10.90% | 2.30 | 11.49 | 13.79 |
| Minnesota | 17.20 | +1.84% | 1.72 | 8.60 | 10.32 |
| Mississippi | 14.43 | +6.02% | 1.44 | 7.21 | 8.66 |
| Missouri | 16.02 | +4.57% | 1.60 | 8.01 | 9.61 |
| Montana | 15.57 | +8.96% | 1.56 | 7.79 | 9.34 |
| Nebraska | 13.54 | +5.78% | 1.35 | 6.77 | 8.12 |
| Nevada | 12.72 | +1.44% | 1.27 | 6.36 | 7.63 |
| New Hampshire | 27.64 | +13.09% | 2.76 | 13.82 | 16.58 |
| New Jersey | 24.61 | -0.36% | 2.46 | 12.30 | 14.77 |
| New Mexico | 16.51 | +3.32% | 1.65 | 8.26 | 9.91 |
| New York | 28.65 | +7.55% | 2.87 | 14.32 | 17.19 |
| North Carolina | 14.95 | +2.47% | 1.50 | 7.47 | 8.97 |
| North Dakota | 13.31 | +2.62% | 1.33 | 6.66 | 7.99 |
| Ohio | 19.38 | +10.43% | 1.94 | 9.69 | 11.63 |
| Oklahoma | 14.82 | +2.77% | 1.48 | 7.41 | 8.89 |
| Oregon | 15.92 | +0.44% | 1.59 | 7.96 | 9.55 |
| Pennsylvania | 21.77 | +9.23% | 2.18 | 10.88 | 13.06 |
| Rhode Island | 28.18 | +6.22% | 2.82 | 14.09 | 16.91 |
| South Carolina | 15.76 | +3.96% | 1.58 | 7.88 | 9.46 |
| South Dakota | 15.15 | +8.99% | 1.52 | 7.58 | 9.09 |
| Tennessee | 13.42 | +2.52% | 1.34 | 6.71 | 8.05 |
| Texas | 15.91 | +3.31% | 1.59 | 7.96 | 9.55 |
| Utah | 13.31 | -2.28% | 1.33 | 6.66 | 7.99 |
| Vermont | 23.84 | +7.87% | 2.38 | 11.92 | 14.30 |
| Virginia | 17.64 | +11.29% | 1.76 | 8.82 | 10.58 |
| Washington | 14.63 | +7.18% | 1.46 | 7.32 | 8.78 |
| West Virginia | 16.31 | +4.42% | 1.63 | 8.15 | 9.79 |
| Wisconsin | 19.41 | +5.26% | 1.94 | 9.71 | 11.65 |
| Wyoming | 14.43 | +0.70% | 1.44 | 7.21 | 8.66 |
No matching state. Try the full state name or reset the table.
2026 prices are preliminary. Use your own utility tariff for a household estimate. The CSV includes 2025 prices and a 233 W scenario.
Best Whole House Fan research team. “21 whole-house fan statistics and running-cost figures (2026).” Published and updated October 24, 2026. https://bestwholehousefan.com/attic-ventilation/whole-house-fan-statistics/
What's covered7
- How much does whole-house fan electricity cost?
- How much airflow and open-window area does a whole-house fan need?
- How much passive vent area and powered-fan intake is needed?
- How much does fan speed change electricity use?
- What does measured cooling research say about humidity?
- Methods and corrections
- Sources
How much does whole-house fan electricity cost?
State prices are reported observations; running costs in the table above are calculated scenarios.
| Price basis | August 2026 |
|---|---|
| U.S. residential price | 18.16¢/kWh |
| Lowest / highest state | Nevada 12.72¢ / Hawaii 47.18¢ per kWh |
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The U.S. average residential electricity price was 18.16 cents per kWh in August 2026, according to EIA Table 5.6.A. (U.S. EIA, October 2026).
The U.S. residential electricity price rose from 17.57 cents per kWh in August 2025 to 18.16 cents in August 2026; the calculated increase is 3.4% after rounding. (U.S. EIA, October 2026).
State residential electricity prices ranged from 12.72 to 47.18 cents per kWh in August 2026, with Nevada lowest and Hawaii highest. (U.S. EIA, October 2026).
How much airflow and open-window area does a whole-house fan need?
Comfort cooling, slower cooling and code compliance use different sizing approaches.
| Sizing approach | Published basis |
|---|---|
| HVI comfort, eight-foot ceiling | 3 CFM per ft² |
| HVI lower cooling rate | 0.4 CFM per ft² |
| PNNL screened-window opening | 4 ft² per 1,000 CFM |
| California 2025 installation form | 1.5 CFM per ft²; California scope |
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HVI sizes whole-house comfort airflow at 3 CFM per square foot of gross home area, including upper stories, with an eight-foot ceiling assumption. (HVI, accessed October 2026).
HVI describes a lower cooling rate of 0.4 CFM per square foot, with separate fans providing the breeze felt by occupants. (HVI, accessed October 2026).
PNNL describes 12–23 air changes per hour as an effective whole-house cooling range, rather than a guarantee for every house. (PNNL, September 2022).
PNNL recommends at least 4 square feet of open screened-window area per 1,000 CFM for whole-house fan operation. (PNNL, September 2022).
PNNL notes that the open area of a sliding window is typically only 1/3 to 1/2 of the full window area; numerically, that is about 0.33–0.5 of the opening. (PNNL, September 2022).
California’s January 2026 CF2R-MCH-02-E instructions calculate the minimum whole-house fan airflow at 1.5 CFM per square foot of conditioned floor area for the applicable 2025 Energy Code compliance calculation. (California Energy Commission, January 2026).
How much passive vent area and powered-fan intake is needed?
Net free area is the usable opening, not the outer size of a vent; use the calculator for your dimensions.
| Air path | Published HVI basis |
|---|---|
| Whole-house fan attic outlet | 1 ft² attic exhaust area per 750 CFM |
| Powered attic fan soffit intake | 1 ft² per 300 CFM |
| Passive attic baseline | Attic floor area ÷ 150 |
| HVI passive planning allocation | 60% low intake / 40% high exhaust |
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HVI calculates vented-attic exhaust for a whole-house comfort fan at 1 square foot of attic exhaust area for every 750 CFM of fan capacity. (HVI, accessed October 2026).
HVI’s passive-attic planning allocation places 60% of net free area at low intake and 40% at high exhaust, separate from local code exception conditions. (HVI, accessed October 2026).
HVI’s passive-attic baseline divides attic floor area by 150 to obtain the required square feet of net free vent area. (HVI, accessed October 2026).
HVI calculates powered-attic fan airflow using 0.7 CFM per square foot of attic floor area, a different task from cooling the living space. (HVI, accessed October 2026).
HVI calls for at least 1 square foot of soffit intake per 300 CFM of HVI-certified powered-attic fan capacity. (HVI, accessed October 2026).
How much does fan speed change electricity use?
Read airflow and watts at the same speed and test basis, rather than combining the largest airflow with the smallest power.
| AirScape Sierra model | Lowest / highest HVI-916 table power |
|---|---|
| 3200 | 18 / 321 W |
| 3400 | 17 / 298 W |
| 4300 | 18 / 515 W |
| 5300 | 36.5 / 932 W |
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AirScape’s Sierra 3400 HVI-916 table spans 17–298 watts across its ten settings; these figures describe one model at different speeds. (AirScape, accessed October 2026).
AirScape’s Sierra 3400 table lists 42.5 CFM per watt at the lowest setting, compared with 11.5 CFM per watt at the highest setting. (AirScape, accessed October 2026).
Field Controls lists the VentCool S3 at 2,740 gross CFM versus 2,210 HVI-916 net CFM, demonstrating why the rating basis must travel with the number. (Field Controls, October 2022).
What does measured cooling research say about humidity?
Historical field results describe their particular buildings and weather; they are not nationwide savings estimates.
| Evidence | Measured result / guidance |
|---|---|
| FSEC: one Cocoa Beach home, summer 1991 | 3–6°F cooler evenings; nighttime RH 74% → 83% |
| EPA moisture guidance | Below 60% RH; ideally 30–50% |
| EPA water-damage response | Dry wet materials within 24–48 hours |
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FSEC’s study of one Cocoa Beach, Florida home in summer 1991 found evening indoor temperatures 3–6°F cooler after whole-house fan operation, as reported in 1992. (Florida Solar Energy Center, 1992).
In the same 1991 Cocoa Beach field study, nighttime indoor relative humidity increased from 74% to 83% during fan-powered ventilation. (Florida Solar Energy Center, 1992).
The U.S. EPA advises indoor relative humidity below 60%, ideally between 30% and 50%, in its household mold and moisture guidance. (U.S. EPA, September 2012).
The U.S. EPA recommends drying water-damaged materials within 24–48 hours to reduce mold growth risk; ventilation does not replace fixing the water source. (U.S. EPA, September 2012).
Methods and corrections
44 candidate figures checked, 21 kept.
The state table uses August 2026 and August 2025 residential prices, released October 23, 2026. Electricity-only examples use 100, 233 or 500 watts; the monthly example runs four hours a day for 30 days. Actual tariffs and operating hours vary. The Florida findings describe one home in summer 1991.
Price review: November 24, 2026; other figures: April 24, 2027. Report a correction with the figure and original source. For your dimensions, use the whole-house fan calculator or attic ventilation calculator.
Sources
[1] (U.S. EIA, October 2026) · Table 5.6.A, released October 23; August 2026 preliminary, August 2025 final.
[2] (HVI, accessed October 2026) · How Much Ventilation Do I Need?; undated guidance.
[3] (PNNL, September 2022) · Whole-House Fans; updated September 29, 2022.
[4] (California Energy Commission, January 2026) · 2025 Energy Code installation instructions, PDF page 174.
[5] (AirScape, accessed October 2026) · Sierra HVI-916 speed tables; undated product page.
[6] (Field Controls, October 2022) · Summit S-Class sheet, PDF page 1.
[7] (Florida Solar Energy Center, 1992) · Measured Natural Cooling Enhancement of a Whole House Fan.
[8] (U.S. EPA, September 2012) · A Brief Guide to Mold, Moisture and Your Home, reprint; linked HTML updated February 2026.