into three main categories based on their use and functionality. Each type offers some unique advantages over the others and hence is suitable for a specific application. These include household, industrial and large-diameter fans. Household fans usually have 4 or 5 wooden blades, a decorative motor housing, and a standard three speed motor with pull-chain switch control. These fans come in two varieties, with or without a light kit, depending on the price and consumer preferences. Commercial or industrial ceiling fans are typically used in stores, schools, churches, offices, factories, and warehouses. Such a fan is designed to be more cost-effective and energy-efficient than its household counterpart. Industrial or commercial ceiling fans typically use three or four blades, typically made of either steel or aluminum, and operate at high speed. These energy-efficient ceiling fans are designed to push massive amounts of air across large, wide open spaces. From the late 1970s to the mid-1980s, metal-bladed industrial ceiling fans were popular in lower-income American households, likely due to them being priced lower than wood-bladed models. Industrial style ceiling fans are very popular for household applications in Asia and the Middle East. HVLS fans are large-diameter ceiling fans, intended for large spaces such as large warehouses, hangars, shopping malls, railway platforms and gymnasiums. These fans generally spin at a lower speed but due to their large diameter, ranging between 7' and 24' (2.1m and 7.3m), can provide a large area with a gentle breeze. Modern HVLS fans use airfoil-style blades for optimized air movement at a reduced energy cost. One of the most notable manufactures of HVLS fans is Big Ass Fans. Indoor/outdoor ceiling fans are designed for use in partially enclosed or open outdoor spaces. The body and blades are made of materials and finishes that are not as drastically affected by moisture, temperature swings, or humidity as traditional materials and finishes. UL Damp-rated fans are suitable for covered outdoor areas like patios and porches that aren't directly exposed to rainwater from above, as well as moisture-prone indoor areas such as bathrooms and laundry rooms. In open places where the fan may come in contact with water, one must use wet-rated fans. UL Wet-rated fans have a completely sealed motor which can withstand direct exposure to rainwater, snow and can even be washed off with a garden hose. Both industrial and residential fans come in dry-rated as well as damp and