While I thought I was lucky enough to escape Europe’s intense June heatwave, I was greeted by equally brutal temperatures upon my return to New York City. With temperatures exceeding 37ºC in the few days leading up to the Fourth of July, I was to be found either at the beach or in the comfort of my air conditioned (AC) home. In New York, and most of the United States, air conditioning is omnipresent. Homes, department and grocery stores, and even public transit are equipped with ACs, providing some relief in the scorching summer sun.
But what was done before the creation of these cooling machines?
A World of Passive Cooling
The earliest forms of air conditioning originated in the Middle East nearly 6,000 years ago. , archaeologists working in Syria found remains of living quarters that appeared to be double walled. It was inferred that this double-walled design allowed air to flow around the building, which lowered indoor temperatures. Other heat-regulation technologies - including thick, mud-brick walls, closely spaced houses, and tiny windows - were used in what is now southern Iraq.
All these strategies can be categorized as . Passive cooling is a cooling method that incorporates Earth’s natural elements into urban design, with the objective of minimizing artificial climate control. Examples of this cooling method are shading, whether that be through vegetation or building organization; cross ventilation which allows air to flow through open windows on opposite sides of a room; and wind catchers, which are architectural structures that trap and channel outdoor breezes through a building before expelling the warm air.
Passive cooling would eventually fall out of fashion, and by the beginning of the 20th century, artificial cooling devices would have the world in their grasp.
The Modern Air Conditioner
In addition to his many other contributions to science, Ben Franklin was also involved in the early experiments that would lay the groundwork for the modern AC. Franklin, alongside chemistry professor John Hadley, demonstrated that the evaporation of (how quickly a liquid turns into a vapor ) liquids could cool an object to below the freezing point of water, despite being in a room that was 18ºC. This had never been done before.
Advancements in compression and refrigeration technology (necessary for AC function) bloomed during the 19th century. In 1820, English scientist, Michael Faraday discovered that if he compressed and liquefied ammonia (a volatile liquid) and then allowed it to evaporate, it cooled the air in his lab. 20 years later, American doctor designed an engine that would compress air to make ice. The machine would then blow air over this ice, which he then used to cool the air for his hospital patients. Despite being patented in 1851, Gorrie’s design was deemed too costly and inefficient to be implemented and manufactured on a wide scale.
Another early form of the modern AC was found in America’s . Recovering from being shot, President James Garfield sought relief from the hot temperatures in his bedroom. U.S. Naval engineers devised an apparatus that utilized a powerful fan blowing air through a box that was lined with ice-water wettened cotton. This air was then pumped through a duct into the president’s bedroom. Allegedly it decreased the room temperature by 20ºF. Despite providing relief, this machine was also ultimately too inefficient for widescale use.
A Happy Accident
It wouldn’t be until 1902 that the unit was installed. Built in response to intense humidity causing the paper at Sackett-Wilhelms Lithographing and Publishing Company in Brooklyn to warp, is credited with being the father of the modern AC we know and love today.
This machine drew air in through a filter, where the air would then cool via coils filled with a coolant inside of the machine. This air, cooled and dehumidified, would be blown back out. Despite the product’s immense success, it wouldn’t be until the early 1930s that the common household AC units we see today would be designed. These units, priced between $10,000-$50,000 USD were a hot commodity, and no small purchase. However, over time, the technology became more refined and more accessible. By the 1960s, these units were sold by the millions in the United States and as of , more than nine out of ten U.S. households have AC units. Despite this staggering statistic, AC availability is not spread out equally across the country. Oftentimes those in marginalized communities have less access to AC units and therefore are more vulnerable to heat risk.
The Environmental Impact of ACs
In 1987, the was established and required the phasing out of ozone depleting chlorofluorocarbons (CFCs). The protocol was amended in 1992 to include phasing out of hydrochlorofluorocarbons (HCFCs). These are gases used in refrigeration and air conditioning units that deplete the ozone layer. According to the United Nations Environment Program (UNEP), the most used HCFC is 2,000 times more potent than carbon dioxide in its global warming potential. As these harmful refrigerants are being phased out, and non-ozone-depleting refrigerants are being introduced in order to have less of an environmental impact.
Despite progress being made to make ACs more environmentally friendly, there are several to stay cool without relying on them. Using cooling sprays or placing a wet towel on your body helps to bring down your body temperature. If nighttime temperatures are more comfortable, you can try opening your windows to let cooler air circulate through your home. Avoid direct sunlight through covering your windows with blinds – or with tin foil! While these strategies for keeping cool can be effective, they don’t always provide the same relief as air conditioning. That is the beauty of the AC. However, now having returned to Prague, where AC is a luxury, I might have to draw on some of these DIY cooling strategies. At least I’ll be saving money on my energy bill!
Eva Kellner is a recent graduate from the Faculty of Arts and Science, with a major in Environment. Her research interests include urban green spaces, urban agriculture, and outdoor community spaces - all as promoters of climate resilience among city-dwellers.
Part of the OSS mandate is to foster science communication and critical thinking in our students and the public. We hope you enjoy these pieces from our Student Contributors and welcome any feedback you may have!
