Big Ass Fans
Big Ass Fans entered the commercial business market in 2008, debuting a line of fans ranging from to in diameter. The following year, it began manufacturing fans in sizes suitable for residential settings. In late 2011, Big Ass Fans acquired a manufacturer of energy efficient residential fans. Haiku models incorporate direct current, permanent magnetics and aerodynamic airfoils making them 80% more efficient than conventional ceiling fans. They held the top 10 spots on Energy Star's Most Efficient 2014 list. In 2014, the company added smart technology SenseME to the Haiku ceiling fan. Haiku with SenseME integrates with the Nest Learning Thermostat through a smartphone app.
Thermal destratification
Because of their size, HVLS fans are normally installed in new construction, rather than retrofits, as the roof structure may have to be redesigned to accommodate the increased weight and size. It's not uncommon to require the relocation of lights, due to strobing as large fan blades pass under them, and sprinkler systems, which typically require unobstructed access to the floor to meet fire code. When used in the summer to encourage evaporative cooling, HVLS fans are run forward, blowing air at the floor. When used for destratification in the winter, the fans are run in reverse, blowing air towards ceiling which then circulates around the room. The height at which HVLS fans can be effective is limited compared to axial destratification fans.