Air Conditioning Wasn’t Invented to Provide Comfort to Human Beings

Its original purpose was to enable factory processes, but now an ever-larger part of the world’s hottest regions is adopting it

3 min read
Image: Nicolas Ayer/EyeEm/Getty Images
Image: Nicolas Ayer/EyeEm/Getty Images

illustration Image: Nicolas Ayer/EyeEm/Getty Images

Air conditioning was devised not for comfort but for industry, specifically to control temperature and humidity in a color printing factory in Brooklyn. The process required feeding paper into the presses a number of times, once for each of the component colors, and the slightest misalignment caused by changes in humidity produced defective copies that had to be thrown away.

In 1902 the factory’s operators asked Willis Haviland Carrier (1876–1950) to help, and he deployed coils [PDF] supplying 211 kilowatts of cooling to maintain a temperature of 27 °C and a relative humidity of 55 percent. Half the cooling was furnished by cold well water, half from mechanical refrigeration based on evaporative cooling—the principle of which had been worked out in the 18th century by several scientists, notably Benjamin Franklin. The system was not a complete success, but Carrier continued his work, eventually publishing the first chart relating temperature, humidity, and the way people perceived these qualities—part of an engineering discipline now known as psychrometrics. In 1906, he obtained his first patent (U.S. Patent 808,897) for the “Apparatus for Treating Air,” and in 1911 he presented his paper, “Rational Psychrometric Formulae,” a lasting foundation for designing efficient air-conditioning systems.

At first, air conditioning was mainly used in the textile, printing, film, and food-processing industries. In the 1920s department stores and movie theaters began to offer it. In 1932 came a limited run of the first individual window units, a type that Philco-York brought to market in 1938—though nonessential A/C installations were temporarily banned during the war.

It took almost another three decades before half the households in the United States had A/C. By 1990, that rate reached 70 percent; now it exceeds 90 percent.

Large-scale migration from the Snowbelt to the Sunbelt drove the adoption, and afterwards household air conditioning began its northerly diffusion. Electricity-generating companies saw their peak production move from the winter months to the summer. Today, U.S. generation at utility-scale facilities is significantly higher in July than in January. In 2018 the difference was about 10 percent [PDF], and in 2019 it was 15 percent.

charts Air conditioning stands to rise markedly in emerging economies, many of which have notably hot weather (top). Cooling takes an ever-larger share of electric capacity, but more efficient air-conditioning units could make a big difference (bottom). Source: International Energy Agency

By 2019 there were more than 1.6 billion units in operation around the world, more than half of them in China and the United States. But this was just the beginning: In 2018 the International Energy Agency predicted a coming “cold crunch” driven by a combination of three key factors: Incomes will continue to rise in the emerging economies, where one of the first spending choices is for a window A/C unit. Global warming will gradually raise summer temperature peaks and increase the number of hot spells. Finally, populations will rise, with more than 90 percent of the increase taking place in the hotter places, such as Africa, the Middle East, and southern Asia.

There’s a lot of growth potential here. Fewer than 10 percent of the nearly 3 billion people who live in the warmest places now have air conditioning in their homes, compared with 90 percent in the United States and Japan. If air conditioning were provided to the more than 200 million inhabitants of Uttar Pradesh, a single state in India whose average summer temperature is far higher than that in Florida, this would require at least twice as much electricity as the cooling demand in the United States, with its 330 million people. And because coal-fired generation provides a large share of the electricity in India, China, and Indonesia, the spread of air conditioning will greatly increase Asia’s emissions of carbon dioxide.

Rising temperatures, rising incomes, and growing populations make the rapid growth of air conditioning unstoppable. All we can do is to moderate that growth rate by better urban planning, smarter building design, and enforcement of strict efficiency standards for new A/C units.

This article appears in the July 2020 print issue as “The Year is 118 A.A.C. (After Air Conditioning).”

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Smokey the AI

Smart image analysis algorithms, fed by cameras carried by drones and ground vehicles, can help power companies prevent forest fires

7 min read
Smokey the AI

The 2021 Dixie Fire in northern California is suspected of being caused by Pacific Gas & Electric's equipment. The fire is the second-largest in California history.

Robyn Beck/AFP/Getty Images

The 2020 fire season in the United States was the worst in at least 70 years, with some 4 million hectares burned on the west coast alone. These West Coast fires killed at least 37 people, destroyed hundreds of structures, caused nearly US $20 billion in damage, and filled the air with smoke that threatened the health of millions of people. And this was on top of a 2018 fire season that burned more than 700,000 hectares of land in California, and a 2019-to-2020 wildfire season in Australia that torched nearly 18 million hectares.

While some of these fires started from human carelessness—or arson—far too many were sparked and spread by the electrical power infrastructure and power lines. The California Department of Forestry and Fire Protection (Cal Fire) calculates that nearly 100,000 burned hectares of those 2018 California fires were the fault of the electric power infrastructure, including the devastating Camp Fire, which wiped out most of the town of Paradise. And in July of this year, Pacific Gas & Electric indicated that blown fuses on one of its utility poles may have sparked the Dixie Fire, which burned nearly 400,000 hectares.

Until these recent disasters, most people, even those living in vulnerable areas, didn't give much thought to the fire risk from the electrical infrastructure. Power companies trim trees and inspect lines on a regular—if not particularly frequent—basis.

However, the frequency of these inspections has changed little over the years, even though climate change is causing drier and hotter weather conditions that lead up to more intense wildfires. In addition, many key electrical components are beyond their shelf lives, including insulators, transformers, arrestors, and splices that are more than 40 years old. Many transmission towers, most built for a 40-year lifespan, are entering their final decade.

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