How much does a whole house fan cost?

Fan unit: traditional: $200-$600. Ducted (QuietCool-style): $500-$1,500. Installation: $300-$1,000. Total installed: $500-$2,500. Operating cost: $0.01-$0.05/hour (vs $0.20-$0.50/hour for AC). Energy savings: $200-$600/year on cooling. Payback: 1-3 years. Best value: a ducted QuietCool-style fan ($700-$1,200 installed). It is whisper-quiet, has an insulated damper, and provides excellent cooling. The higher upfront cost is offset by dramatic energy savings.

Whole house fan vs AC — which is better?

They serve different purposes and work best together. Whole house fan: uses 90% less energy, cools the house in minutes, provides fresh air, and is ideal for evenings and mornings when outside air is cool. Only works when outside air is cooler than inside (typically below 80-85 degrees F). AC: works in any weather, dehumidifies, and can maintain a precise temperature. Uses 10-20x more energy. Best strategy: use the whole house fan whenever outside air is cool enough (evenings, nights, mornings), and run AC only during the hottest part of the day. This can reduce AC usage by 50-90% and save $200-$600/year.

Are whole house fans loud?

It depends on the type. Traditional belt-drive fans: YES, quite loud. The large fan blade and motor create significant noise (comparable to a large window fan on high). Direct-drive fans: moderately loud. Ducted fans (QuietCool-style): whisper-quiet on low speed (comparable to a bathroom exhaust fan). The ducted design isolates the motor in the attic and uses insulated ducting to reduce noise transmission. If noise is a concern: choose a ducted/QuietCool-style fan. They cost more but the noise reduction is dramatic.

How do I size a whole house fan?

Formula: square footage × ceiling height ÷ 2 = minimum CFM. 1,500 sq ft × 8 ft = 12,000 ÷ 2 = 6,000 CFM. 2,000 sq ft × 8 ft = 16,000 ÷ 2 = 8,000 CFM. 2,500 sq ft × 8 ft = 20,000 ÷ 2 = 10,000 CFM. Important: your attic must have adequate ventilation. Rule: 1 sq ft of net free venting per 750 CFM. An undersized attic vent system reduces fan effectiveness and can pressurize the attic. If your attic venting is insufficient, add more ridge, gable, or soffit vents before installing the fan.

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Woodworking & Lumber

Whole House Fan Guide: Types, Sizing & Cost

Lumberama Editorial Team, Home Cooling & Ventilation Specialists Sep 5, 2026 12 min read

What Is a Whole House Fan

A whole house fan is a large fan mounted in the ceiling (usually in a hallway) that pulls cool outside air in through open windows and pushes hot air out through the attic and roof vents. It is NOT the same as an attic fan (which only vents the attic). A whole house fan cools the entire living space. Benefits: uses 90% less energy than AC (costs pennies per hour to run), cools the house in minutes (much faster than AC), cools the attic (reducing heat buildup), and provides fresh air circulation. Limitation: only works when outside air is cooler than inside air (evenings, nights, and cool mornings). Not a replacement for AC in hot, humid climates, but an excellent supplement.

Types

Traditional (belt-drive): A large fan blade (24-48 inches) mounted in the ceiling with a belt-driven motor. Pros: very powerful (moves 3,000-6,000+ CFM), proven technology, and inexpensive. Cons: LOUD (the main drawback), large ceiling opening (requires significant framing), and difficult to install. Cost: $200-$500 (unit).

Direct-drive: Similar to traditional but the motor connects directly to the fan blade (no belt). Pros: quieter than belt-drive, less maintenance (no belt to replace), and more compact. Cons: still relatively loud and requires a large ceiling opening. Cost: $300-$600 (unit).

Ducted (QuietCool-style): Multiple smaller fans connected to insulated ducts. The fan motor is in the attic and the intake is a small ceiling vent. Pros: MUCH quieter (whisper-quiet on low speed), small ceiling opening (easy installation), insulated damper (seals when not in use), and can install multiple units for zoning. Cons: more expensive per CFM. Cost: $500-$1,500 per unit. The most popular type for modern installations.

Insulated damper models: Any type with an insulated damper that seals when the fan is off. Critical for energy efficiency: without a damper, conditioned air escapes through the ceiling opening in winter. All modern ducted fans include this.

Sizing

Whole house fans are rated in CFM (cubic feet per minute). The rule: you want to exchange the entire volume of air in your house every 2-3 minutes.

Formula: Square footage × ceiling height ÷ 2 = minimum CFM. Example: 2,000 sq ft house × 8 ft ceilings = 16,000 cubic feet ÷ 2 = 8,000 CFM minimum.

General guidelines: 1,000-1,500 sq ft: 3,000-4,500 CFM. 1,500-2,500 sq ft: 4,500-7,500 CFM. 2,500-3,500 sq ft: 7,500-10,000 CFM. 3,500+ sq ft: 10,000+ CFM (or multiple units).

Attic ventilation: Your attic needs 1 sq ft of net free venting area per 750 CFM. An 8,000 CFM fan needs ~10.7 sq ft of attic venting (ridge vents, gable vents, soffit vents, etc.). Insufficient attic venting reduces effectiveness and can pressurize the attic.