HVLS Fan Co. (Lexington, KY) says its fans are based on the same principles as residential ceiling fans, except they are right-sized for warehouses, industrial plants, and distribution centers. It says its low-speed, ceiling-mounted fans can circulate air over an area in excess of 15,000 sq ft. They are designed to be effective in buildings with ceilings that are 45 ft or more in height. The company's 20-ft fan has 10 airfoils that are 10 ft long each.