Keeping Cool: The Air Conditioner That Changed America - Human Progress

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Summary: Air conditioning has transformed extreme heat from a major threat into a manageable challenge, helping save lives, improve productivity, and make hot climates far more livable. Since its invention in the early 20th century, advances in technology and rising prosperity have made cooling dramatically more affordable, with the time required to earn an air conditioner falling by nearly 99 percent since 1952. Differences in air-conditioning adoption help explain why heat-related mortality remains much higher in Europe than in the United States, underscoring the role of innovation, wealth, and energy policy in protecting human wellbeing.

Heatwaves have pushed temperatures to record highs across both Europe and the United States. Yet the human toll between these two locales was dramatically different, with Europe recording more than 10,000 excess deaths in June.

This is a familiar pattern, notes Jack Nicastro:

The United Nations estimates that the European continent accounted for approximately 175,000 heat-related deaths annually between 2000 and 2019. The Environmental Protection Agency, meanwhile, calculates that about 1,300 deaths per year in the US are due to extreme heat. (This translates to four heat-related deaths per million annually in the US and 235 heat-related deaths per million annually across Europe.)

Europe and the US differ in demographics, urban density, reporting methods, and climate patterns. Even so, the death rate due to heat in Europe is 59 times higher than in the US.

In the United Kingdom, only about five percent of homes have air conditioning. In the United States, roughly 93 percent do.

Research identifies 72°F and 45 percent humidity as optimal for maximizing office and mental productivity.

With sweltering temperatures once again gripping much of the world, it is worth appreciating air conditioning — the quiet invention that transforms dangerous heat into manageable discomfort, shields millions from heat-related suffering and death, boosts productivity, and makes once-hostile climates livable. It is a powerful reminder that wealth, innovation, and human ingenuity enable societies to adapt to nature’s extremes and protect human life.

To understand why the US heat death rate is 59 times lower than that of Europe, it helps to begin with a young engineer named Willis Carrier.

The Father of Air Conditioning

Willis H. Carrier was born outside of Buffalo, New York on November 26, 1876, the same day inventor Alexander Graham Bell successfully demonstrated his large box telephone between Boston and Salem, Massachusetts. Carrier was an only child and attended a one-room schoolhouse. When he was nine years old he struggled to grasp the concept of fractions. His mother helped him master the idea using a pot of apples and slicing them into portions. Carrier remembered this event fondly as “the most important thing that ever happened to me.”

Carrier was awarded a full scholarship to attend Cornell University. He majored in engineering, earning a Master’s degree in 1901. After graduation, Carrier accepted a job at the Buffalo Forge Company for $10 a week.

The Sackett & Wilhelms printing plant in Brooklyn, New York was losing money because the sweltering, humid summers caused sheets of paper to absorb moisture from the air. The paper would expand and warp, throwing off the alignment of colored inks on the printed page and ruining entire print runs. They asked the Buffalo Forge Company for help. Carrier was assigned to solve the problem.

He was not trying to cool people. He was trying to save knowledge.

Air conditioning began not as a luxury, but as a technology of information, productivity, and adaptation — a machine that transformed oppressive heat from an economic barrier into a manageable inconvenience.

Carrier’s breakthrough system, in July of 1902, controlled both temperature and humidity, stabilizing the paper and rescuing the precision of mass communication.

Carrier applied for a patent on his invention, an “Apparatus for Treating Air,” which became patent No. 808897 and was issued on January 2, 1906.

On December 3, 1911, Carrier presented what is perhaps the most significant document ever prepared on air conditioning – Rational Psychrometric Formulae – at the annual meeting of the American Society of Mechanical Engineers. It became known as the Magna Carta of Psychrometrics and tied together the concepts of relative humidity, absolute humidity, and dew-point temperature, thus making it possible to design air-conditioning systems to precisely fit the requirements at hand.

In 1915 Carrier and six other engineers formed the Carrier Engineering Corporation using their personal savings of $32,600. Carrier Global Corporation (NYSE: CARR), the parent company of the Carrier HVAC and refrigeration business, has a current market capitalization of approximately $56 billion. This valuation...