Every whole house fan gets a score from 0 to 100% built from five factors, which maps onto the 5-point rating shown on the site (a 0% score would be 1.5 stars; a perfect score, 5). Each factor is scored against fixed reference points, not against the other products in the list, so adding a new model never moves another model’s rating. Fans are grouped by airflow (up to 3,000 CFM, 3,001 to 5,000 CFM and over 5,000 CFM).
| Factor | Measures | Weight |
|---|---|---|
| Value | price per 1,000 CFM of airflow | 30% |
| Efficiency | airflow per watt at high speed | 20% |
| Noise | rated sound level at high speed | 15% |
| Damper | insulation of the damper that seals the opening in winter | 10% |
| Warranty | warranty on the motor | 25% |
Where the numbers come from
Airflow and power come from the California Energy Commission’s appliance listing when the model is on it, and otherwise from the maker’s spec sheet. The commission’s figures are measured to HVI 916 through the damper and ducting, so they run 20 to 30% below the free-air airflow many makers print in their model names (a QuietCool ES-7000 is certified at 5,170 CFM). The product page gives both. Noise, damper insulation and warranty come from the maker’s spec sheet, manual or product page. Prices are checked at Amazon, the maker’s own store and home improvement retailers, and the lowest is used.
The factors
Value is the current price divided by the rated airflow at high speed, per 1,000 CFM, on a log scale, so going from $800 to $400 counts as much as going from $400 to $200. $900 per 1,000 CFM scores zero and $220 full marks.
Efficiency is airflow per watt at high speed: 5 CFM per watt scores zero and 11 full marks. A fan that runs every summer evening for years costs far more in power than its price gap.
Noise is the maker’s rated sound level at high speed: 70 dBA scores zero and 40 dBA full marks. Makers measure at different distances, which the product page notes when given.
Damper is the insulation of the damper or door that closes the ceiling opening when the fan is off. An uninsulated louver scores zero and R-15 full marks, since an open grille in the ceiling loses heat all winter.
Warranty is the warranty on the motor: 1 year scores zero and 10 years full marks.
What isn’t scored
Mount type, number of speeds, remote control, app control and the attic vent area the maker asks for are listed but not scored. Ducted fans have their own page.
Missing data
If a figure isn’t published, that factor gets the neutral middle score (50) and the product page marks it as estimated.
Ties and discontinued models
Products are ranked by score within each group. Discontinued models stay listed but rank below every current model and can be hidden with the “Hide discontinued” filter.