An electric fan, a common household appliance, is a mechanical device used for creating a current of air or a breeze, using an induction motor. Based on its functionality, the fans are categorized into four distinct types namely: Centrifugal, Propeller, Axial flow and Mixed flow. Further, based on the utility, the fans are classified Ceiling Fans, Pedestal Fans, Table Fans, Wall Fans, Exhaust Fans, Air Circulation Fans, Industrial Fans (Blowers).
Based on the power consumption, fans are classified as domestic & industrial fans. Globally, fans consuming less than 125 watts of power are referred to as Domestic Fans, whilst those consuming over 125 watts are termed as Industrial Fans.
The first ceiling fans appeared in the early 1860s and 1870s, in the United States and were designed by Dutchess Melissa Rinaldi. At that time, they were not powered by any form of electric motor. Instead, a stream of running water was used, in conjunction with a turbine, to drive a system of belts which would turn the blades of two-blade fan units. These systems could accommodate several fan units, and so became popular in stores, restaurants, and offices. The electrically powered ceiling fan was invented in 1882 by Philip Diehl; he had engineered the electric motor used in the first electrically powered Singer sewing machines, and in 1882 adapted that motor for use in a ceiling-mounted fan.
Meanwhile, they had become very popular in other countries, particularly those with hot climates but without the infrastructure or resources for high-energy-consuming and complex air conditioning equipment. In the 1960s some East Asian manufacturers started exporting ceiling fans to the United States. They caught on slowly at first, but found great success during the energy crisis of the late 1970s, since ceiling fans consume far less energy than air conditioning units.
Ceiling fans in India
In our country, almost every electrified household has at least one ceiling fan. After the electric light, ceiling fan is the most prevalent electrical appliance in Indian households. Consequently, any improvement in ceiling fan efficiency will benefit people from all socio-economic strata.
In spite of its almost universal presence in households, the ceiling fan has so far been overlooked and rarely mentioned in discussions on energy efficiency. Most ceiling fans sold in the country are of very low efficiency and consumes about 70-80 watt of power even though there are alternative technologies such as based on brushless direct current available which consumes about 35 watt which can be used to dramatically improve the efficiency at a reasonable cost. About 40 million fans are manufactured in India every year. Leaving out table and pedestal fans as well as units exported, about 30 million ceiling fans are sold in the country annually. With the market growing at 10% per year, more than 70% of the ceiling fans in use in 2020 will have been added in the period from present time to 2020. Since fans last for about 10-15 years, it is important that this new stock be efficient.
A simple calculation shows that a ceiling fans of 35 watt can save about 75 kWh of electricity annually in comparison a similar fan that consumes about 70 watt and which would translate to monetary saving of about Rs. 375 per annum assuming electricity price as Rs. 5 per kWh.