The Bay Area's cool evenings make whole house fans an excellent, energy-efficient cooling option.
What is a Whole House Fan?
A whole house fan is a large fan mounted in the ceiling that: - Pulls cool outside air through open windows - Exhausts hot air through attic vents - Cools the entire house quickly - Uses 90% less energy than AC
How They Work
- Open windows on desired side of house
- Turn on fan (manual or thermostat)
- Cool air drawn in through windows
- Hot air pushed out through attic
- House cools in 10-20 minutes
Perfect for Bay Area Climate
Why Bay Area Works - Cool evenings even after hot days - Coastal influence cools most nights - Many nights below 70°F - Less AC needed overall
Best Conditions - Outdoor temp 70°F or below - Lower humidity - Evening through morning hours
Types of Whole House Fans
Traditional (Belt-Driven) - Powerful airflow - Loudest option - Lowest cost - Best for larger homes
Direct Drive - Moderate noise - Good value - Reliable
QuietCool Style - Multiple quiet motors - Very low noise - Higher cost - Best for noise-sensitive
Sizing Your Fan
CFM Requirements | Home Size | Recommended CFM | |-----------|-----------------| | 1,000 sq ft | 3,000-4,000 | | 1,500 sq ft | 4,500-6,000 | | 2,000 sq ft | 6,000-8,000 | | 2,500+ sq ft | 8,000-10,000+ |
Attic Ventilation Fan requires adequate attic venting: - 1 sq ft net free area per 750 CFM - May need to add venting
Installation Considerations
Location - Central hallway ideal - Near bedrooms - Avoid bathrooms
Ceiling Access - Needs attic access - Consider joists and framing - Professional installation recommended
Cost - Fan: $300-$1,500+ - Installation: $300-$600 - Attic venting (if needed): $200-$500
Using Your Whole House Fan
Best Practices - Wait until outdoor temp drops - Open windows opposite fan - Open roughly 2x fan opening area - Run 15-30 minutes typically - Close windows after, retain cool air
When Not to Use - Hot evenings (above 75-78°F) - High humidity days - Wildfire smoke present - High pollen count (allergy sufferers)
Whole House Fan + AC
Complementary Approach - Use fan for evening/night cooling - Pre-cool house before bed - AC for hottest afternoons only - Dramatic energy savings
Timing Strategy 1. Evening: Run whole house fan 2. Night: Sleep with windows closed 3. Morning: House stays cool 4. Afternoon: AC if needed
Energy Savings
Cost Comparison - AC: 2,000-5,000 watts - Whole house fan: 200-700 watts - 90% energy reduction when fan can be used
Bay Area Potential - Many nights fan-only is sufficient - AC use reduced 50-70% - Payback: 1-3 years typically
Maintenance
- Clean blades annually
- Check belt tension (belt drive)
- Ensure attic vents clear
- Listen for unusual sounds
Whole house fans are perfect for the Bay Area. They leverage our natural cooling advantage and can dramatically reduce AC costs.