The physics behind all fan technology is known as the Fan Affinity Laws. These laws control the way a fan’s speed, size, air movement capacity, and power consumption work together. Assuming the fan blade size in a given manufacturer’s solar attic fan remains constant for all fan models, the fan affinity laws simplify to the equation shown at right. This equation gives the relationship between the air flow performance of any manufacturer’s two fan models vs. the required amount of solar power needed to operate the fans at the claimed performance levels.
In general terms, with every 10% increase in a fan’s air flow performance, the power required to operate the fan increases by 33%. For example, an Attic Breeze® 14 inch fan rated for 1550 CFM at 25 watts can be operated at 1800 CFM when using a 40 watt solar panel. Based on this relationship, the graph below shows air flow performance curves for solar attic fans manufactured with 12 inch diameter blades, as well as the 14 inch diameter Attic Breeze® solar attic fan models.
As shown above, Attic Breeze® solar attic fans out perform similar products featuring 12 inch diameter fan blades with comparable power ratings. Based on the fan affinity laws, to achieve that same 1550 CFM performance of our residential 25 watt Attic Breeze® model series, an alternative manufacturer’s 12 inch fan would require at least 38 watts of solar power! Believe the physics, not the marketing.
Designed by Physics. Engineered for Performance.
The clear choice is Attic Breeze®.