The need for ventilation

Houses made out of brickwork and clay featured ventilation mechanisms through windows, vent holes, slots, vents above the cooking pit or ventilators powered by rotating impellers in front of the window. The need for supporting ventilation arose from the airtight construction of the buildings and therefore the insufficient exchange of air. Even long before hygienist Max von Pettenkofer discovered in 1858 that a thousandth of the gas carbon monoxide in the breathing air is hazardous to the health, “foul“ air was feared to due to its harmfulness. Carbon dioxide is a natural part of the air with a content of 0.04 percent (400 ppm). The breathing of animals and humans alike is the main cause for increased concentration in enclosed room, fireplaces and sources of heat do the rest. Physical activities and combustion processes accelerate the increase of CO₂ contents. The gas is heavier than the rest of the breathing air and drops to the ground. Particularly ships with several decks, mines, underground corridors, sick rooms, hospitals, prisons and cellars were affected by the “foul“ air. Symptons such as feeling unwell, problems with concentration, headache, shortage of breath, dizziness, unconsciousness and death were the result. The amount of germs and risk of contamination with infectious diseases also increases with an elevated carbon dioxide content. It might seem harmless and unlikely, however in the past these circumstances were fatal: Europe experienced a wave of smallpox infection in the 18th century, before that the plague and leprosy haunted the population.

A journey through time

Fans driven by the muscular strength of humans were first documented in Chinese records in the year 180 AD. When people started to vitrify window openings by 1180, indoor ventilation and hygienic air became important topics. Since not everyone could afford a servant “ventilator”, other ways were found to intensify natural air circulation. Small centrifugal fans, a kind of wind barrel were installed at the top of the living room window. The impellers inside the cylindrical sheet metal case began moving once warm indoor air rose up and streamed out. Cool, fresh was able to penetrate the building, however the effect was so little it was barely noticeable. Natural ventilation had to be supported manually and with bellows. Other methods of ventilation were the trompe apparatus and centrifugal engine, water wheel fans and impeller fans. These devices were the foundation of the future development of the ventilator.

Ventilation on ships in the 18th century

Conquering the seas has been practically always been part of humankind’s evolution. Scientists assume that humans used ships as far as 50,000 years ago to reach Australia. Exploring new territories, relocation, opening new trade routes, looking for food and transport were often a lot easier than traversing the mainland that was abundantly covered with vegetation. In 1610 the construction of three-storey sailing ships began. The speed of the sailors depended on favourable winds and impacted by bad weather. Whether the destination of the voyage would be reached within just about a month or half a year was mostly impossible to estimate, even for an experienced captain. The crew of English transportation ships was living in close quarters throughout the undetermined duration of the travel. Documentation dating back to this time mentions ceilings so low that one could not stand upright in the room, not even sit properly on the bed frame. It was dark and the wood of the lower level was always damp due to the influence of the “infamous” paddock. The smell of the lower level was compared to spoiled cheese and rancid butter. The crew was “compressed, stacked and pickled like herring”, a bed frame designed for six people was already too small for four crew members. During the transport of slaves from the West African coast about seven percent of the people died during transit alone. The ship’s carpenter and others working in the lower decks often suffocated due to lack of air ventilation. Early reports falsely attribute the awful circumstances to carbon dioxide, though what they really meant was CO carbon monoxide. The air inside the ship was declared to be “rotten” and made responsible for decaying diseases like scurvy. Big efforts were made to extract the bad air from the hull with the help of ventilation mechanisms. Huge impellers sucked out air from the ship’s rooms and tween decks, and pumped in fresh air from the outside. These impellers were operated by one man who was named the “ventilator”. Once ship docked in the port, it was brought into an inclined position to make sure air could escape easier.

In order to improve the time-consuming, tiring ventilation measures, English physiologist and clergyman Stephen Hales introduced his own ideas about enhancing ventilation on ships. He was right in his assumption that diseases on ships were caused by exhalation and evaporation that simply could not escape and was trapped between the ship’s decks. Hales invention was similar to large bellows. Depending on the set-up of the machine air was transported to its destination point through valves, either to the outside or the inside. The device needed constant operation by two men, meaning the entire crew frequently took turns. In the end, the purpose of this accomplishment was not just to increase comfortableness, but also to supply fresh air. The advantage of Hales’ development was, according to the creator himself, that about 5000 cubic metres air were circulated per hour, a much higher figure than the usual impeller would have moved. The generated air circulation felt quite unpleasant though, the inventor said.
In the same year of 1741, member of Royal Society of Sciences in Uppsala and engineer Mårten Triewald introduced another ventilator that circulated 843,820m³ air per hour. Some of the old sources estimate even 25,000 tons of air per hour. German machine director Johann Justus Bartels is another notable inventor of a similar ventilation appliance. Due his high profile, it was Hales who became known as the inventor of the ventilator in the end.

Thanks to the aforementioned accomplishments, maritime transport developed so quickly and well that far away continents became accessible and ready for colonization. Due to extensive size and energy demand (muscular strength) of the machines other kinds of ventilation took hold, though. Samuel Sutton contributed a different method of ventilation that reduced efforts tremendously. Air pipes utilising fire and steam were implemented. In 1769 the steam engine by James watt were applied, by about 1820 ventilators in vessels were completely steam-driven. As time went by, more and more people decided to travel by ship, meaning passenger ships became more common. Thus, the demand for comfort on board increased as well. Willis Carrier, an American engineer, successfully applied for a patent for an appliance described as Apparatus for Treating Air in the year 1906. Like the name suggests, the device would be used for treating air, including the processes of dehumidification and humidification. Nowadays, ventilation systems on ships include modern inventions like air filters or preheaters. The latter are used to warm up cold incoming air during the winter and in harsh weather conditions. Centuries ago, pioneers could only dream of convenient amenities like this.

Fans from the 19th century

One of the first fan factories was opened in Frankfurt, Germany in 1851 by engineer Christian Schiele. He produced blowers based on Hales’ concept. The appliances could be operated by hand or foot. Starting from 1860, axial-flow ceiling fans were manufactured in the USA. They were driven by belts and steam engines. These fans provided a considerably higher airflow. The Antique Fan Museum in the United States of America shows a lot of other oddities and stages of development, for example a fan powered by beer. By the mid of the 19th century electric power was used for technical appliances. In 1882 the first ceiling fan with an electric motor was introduced to the US market by Philip Diehl. Within just 40 years the ceiling fan became part of the standard equipment in every household. In 1887 Diehl applied for a patent for the electric ceiling fan that was granted in 1889. On the European continent centrifugal fans were produced by Benno Schilde GmbH due to their incredibly powerful air pressure. They were applied to ventilation systems where transported air had to cover a long distance through pipes and shafts. Soon other types of axial-flow and centrifugal-flow fans were introduced in the form of desk, pedestal and floor fans with smaller but powerful electric motors. The patent for the electric fan was gratned to engineer James Wood in 1902. Other manufacturers relied on further development of existing technology. Currently, (ceiling) fans are blooming due to the desire for energy-efficient air conditioning. Airtight, heat-insulated new buildings new require ventilation technology. Sensors that react to humidity, smoke or heat automatically activate the ventilation device. Ceiling fans with LED light, high-performance motors and minimum operational noise consume as little as 3 Watt. Options with heat recovery, timer, dimmer, water ingress protection, various controllers and up to 6 fan speeds are available today. In fact, there are so many designs that anyone can find the right device for their home or other field of application.

Summary

Mechanical ventilation, for example by using bellows, water wheels or impellers made of steel sheet, were enough to spark a fire in the fireplace etc. However, they did not provide sufficient air exchange for hospitals, prions and other enclosed premises with few windows. Particularly workers underground and on multi-level sailing ships lost their lives due to unhealthy condition of the air. In 1741, Englishman Hales invented a machine similar to a bewllows that was able to supply and extract air from the vessel’s body. Thus, human CO₂ emission was controlled and transported away, breathing air was cleaner. In the same year, Swiss inventor Triewald presented a similar fan. Both inventions required human interference, they were operated manually and required a lot of effort. However, they proved to be a success in the naval force. Smaller devides were operated by air pipes above the kitchen fireplace. Upon the spread of electric power, manual appliances and steam engines were replaced by electric fans. As these motors could be constructed in smaller sizes as well, desk fans and pedestal fans soon followed. Early fans served to supply and exchange air. The goal was to direct the airflow to a certain point and circulate it in the direction where it was needed. In fact, the cooling was simply a side effect. This was very important for industry sector, though, where motors required cooling. In 1882, the first electric ceiling fan hit the market in North America. It only took four decades to become a nationwide household appliance. Nowadays, fans are still available with traditional designs, however they feature state-of-the-art technology on the inside. DC (direct current) motors provide energy-efficient cooling and heat recovery with a power consumption of just 3 Watt. Low energy components and multi-functional equipment are a given.