What's the deal with those big ceiling fans?
You may remember when Big Ass Fans appeared on the market years ago…of course the name grabbed attention, as the company was one of the first to offer industrial-size fans for the home.
We're talking about HVLS fans. HVLS stands for High Volume Low Speed. HVLS fans have a blade diameter (tip to tip) of 7 feet or more, and operate between 61-220 rpm. They are incredibly energy efficient, because they move large volumes of air (hence the name) with small motors of 1 hp or less that turn relatively slowly. Ceiling fans produce a jet of downward moving air that turns horizontal when it hits the floor, producing a horizontal floor jet, which continues to a wall or vertical structure. A large, slow-moving column of air actually penetrates farther into a room than a small, turbulent one, and creates a taller horizontal floor jet. The main objective of HVLS fans is evaporative cooling, assisting our bodies in cooling by increasing evaporation rates.
HVLS fans were originally developed in the late 1990’s for the dairy industry, to cool large milking houses. The larger the fan, the deeper the horizontal floor jet. For comparison, an 8 foot diameter fan produces a floor jet approximately 36” deep. A fan of 24 feet diameter can produce a 108” deep floor jet, which can cool a standing human or cow (Wikipedia). The benefits of HVLS fans extend to warehouses, factories and homes with large spaces and high ceilings.
Increased evaporative cooling actually decreases air conditioning requirements, because individuals feel cooler at the same dry bulb temperature. Increased air circulation in a room also lowers humidity, to reduce mold issues.
With about 30 years since development, HVLS fans are now widely available for industrial, commercial and home applications, and the newest differentiation adds air purification technology.
Big Ass Fans has several HVLS models with polar ion generators installed at the tip of each blade, and claim to produce higher in-room levels of ions than HVAC-installed systems.
Big Ass Fans has several HVLS models with UV-C lights installed on the top side of the motor shroud, pointing toward the ceiling, so that UV light can kill pathogens in the air without being a safety concern to the room occupants.
So there you have it–if you have a big room, it’s worth getting a big fan for it!