Air Conditioning and Refrigeration History

But the engineering principle on which it is based, mechanical refrigeration, has had even more far-reaching effects, through both refrigeration itself and its close cousin, air conditioning. Taken together, these cooling technologies have altered some of our most fundamental patterns of living. Our daily chores are different. What we eat and how we prepare food have both changed. The kinds of buildings we live and work in and even where we choose to live across the whole length and breadth of the United States all changed as a result of 20th-century expertise at keeping things cool.

Look back for a moment to the world before the widespread use of refrigeration and air conditioning—a world that was still very much present well into the first decades of the 20th century. Only fresh foods that could be grown locally were available, and they had to be purchased and used on a daily basis. Meat was bought during the daily trip to the butcher's; the milkman made his rounds every morning. If you could afford weekly deliveries of ice blocks—harvested in the winter from frozen northern lakes—you could keep some perishable foods around for 2 or 3 days in an icebox. As for the nonexistence of air conditioning, it made summers in southern cities—and many northern ones—insufferable. The nation's capital was a virtual ghost town in the summer months. As late as the 1940s, the 60-story Woolworth Building and other skyscrapers in New York City were equipped with window awnings on every floor to keep direct sunlight from raising temperatures even higher than they already were. Inside the skyscrapers, ceiling and table fans kept the humid air from open windows at least moving around. Throughout the country, homes were built with natural cooling in mind. Ceilings were high, porches were deep and shaded, and windows were placed to take every possible advantage of cross-ventilation.

By the end of the century all that had changed. Fresh foods of all kinds were available just about anywhere in the country all year round—and what wasn't available fresh could be had in convenient frozen form, ready to pop into the microwave. The milkman was all but gone and forgotten, and the butcher now did his work behind a counter at the supermarket. Indeed, many families concentrated the entire week's food shopping into one trip to the market, stocking the refrigerator with perishables that would last a week or more. And on the air-conditioning side of the equation, just about every form of indoor space—office buildings, factories, hospitals, and homes—was climate-controlled and comfortable throughout the year, come heat wave or humidity. New homes looked quite different, with lower rooflines and ceilings, porches that were more for ornament than practicality, and architectural features such as large plate glass picture windows and sliding glass doors. Office buildings got a new look as well, with literally acres of glass stretching from street level to the skyscraping upper floors. Perhaps most significant of all, as a result of air conditioning, people started moving south, reversing a northward demographic trend that had continued through the first half of the century. Since 1940 the nation's fastest-growing states have been in the Southeast and the Southwest, regions that could not have supported large metropolitan communities before air conditioning made the summers tolerable

Mechanical refrigeration, whether for refrigeration itself or for air conditioning, relies on a closed system in which a refrigerant—basically a compound of elements with a low boiling point—circulates through sets of coils that absorb and dissipate heat as the refrigerant is alternately compressed and allowed to expand. In a refrigerator the circulating refrigerant draws heat from the interior of the refrigerator, leaving it cool; in an air conditioner, coils containing refrigerant perform a similar function by drawing heat and moisture from room air.

This may sound simple, but it took the pioneering genius of a number of engineers and inventors to work out the basic principles of cooling and humidity control. Their efforts resulted in air conditioning systems that not only were a real benefit to the average person by the middle of the 20th century but also made possible technologies in fields ranging from medical and scientific research to space travel.

Prominent among air-conditioning pioneers was Willis Haviland Carrier. In 1902, Carrier, a recent graduate of Cornell University's School of Engineering, was working for the Buffalo Forge Company on heating and cooling systems. According to Carrier, one foggy night while waiting on a train platform in Pittsburgh he had a sudden insight into a problem he had been puzzling over for a while—the complex relationship between air temperature, humidity, and dew point. He realized that air could be dried by saturating it with chilled water to induce condensation. After a number of experimental air conditioning installations, he patented Dew Point Control in 1907, a device that, for the first time, allowed for the precise control of temperature and humidity necessary for sophisticated industrial processes. Carrier's early air conditioner was put to use right away by a Brooklyn printer who could not produce a good color image because fluctuations of heat and humidity in his plant kept altering the paper's dimensions and misaligning the colored inks. Carrier's system, which had the cooling power of 108,000 pounds of ice a day, solved the problem. That same principle today makes possible the billion-dollar facilities required to produce the microcircuits that are the backbone of the computer industry. Air conditioners were soon being used in a variety of industrial venues. The term itself was coined in 1906 by a man named Stuart Cramer, who had applied for a patent for a device that would add humidity to the air in his textile mill, reducing static electricity and making the textile fibers easier to work with. Air-conditioning systems also benefited a host of other businesses, enumerated by Carrier himself: "lithography, the manufacture of candy, bread, high explosives and photographic films, and the drying and preparing of delicate hygroscopic materials such as macaroni and tobacco." At the same time, it did not go unnoticed that workers in these air-conditioned environments were more productive, with significantly lower absentee rates. Comfort cooling, as it became known, might just be a profitable commodity in itself.

Carrier and others set out to explore the potential. In 1915 he and several partners formed the Carrier Engineering Corporation, which they dedicated to improving the technology of air conditioning. Among the key innovations was a more efficient centrifugal (as opposed to piston-driven) compressor, which Carrier used in the air conditioners he installed in Detroit's J. L. Hudson Department Store in 1924, the first department store so equipped. Office buildings soon followed.  


Even as Willis Carrier was pioneering innovations in industrial air conditioners, a number of others were doing the same for comfort cooling. Beginning in 1899, consulting engineer Alfred Wolff designed a number of cooling systems, including prominent installations at the New York Stock Exchange, the Hanover National Bank, and the New York Metropolitan Museum of Art. The public was exposed to air conditioning en masse at the St. Louis World's Fair in 1904, where they enjoyed the air-conditioned Missouri State Building. Dozens of movie theaters were comfort cooled after 1917, the result of innovations in theater air conditioning by Fred Wittenmeier and L. Logan Lewis, with marquees proclaiming "It's 20 degrees cooler inside." Frigidaire engineers introduced a room cooler in 1929, and they, along with other companies such as Kelvinator, General Electric, and York, pioneered fully air-conditioned homes soon after.

Refrigerators did not represent quite as much of a revolution. Many people at the turn of the century were at least familiar with the concept of a cool space for storing food—the icebox. But true mechanical refrigeration—involving that closed system of circulating refrigerant driven by a compressor—didn't come along in any kind of practical form until 1913. In that year a man named Fred Wolf invented a household refrigerator that ran on electricity (some earlier mechanical refrigerators had run on steam-driven compressors that were so bulky they had to be housed in a separate room). He called it the Domelre, for Domestic Electric Refrigerator, and sold it for $900. It was a quick hit but was still basically an adaptation of the existing icebox, designed to be mounted on top of it. Two years later Alfred Mellowes introduced the first self-contained mechanical refrigerator, which was marketed by the Guardian Refrigerator Company. Mellowes had the right idea, but Guardian didn't make what it could of it. In 2 years the company produced a mere 40 machines.

Into the breach stepped one of the giants of the automotive industry, William Durant, president of General Motors. Realizing the potential of Guardian's product, he bought the company in 1918, renamed it Frigidaire, and put some of GM's best engineering and manufacturing minds to work on mass production. A few years later Frigidaire also bought the Domelre patent and began churning out units, introducing improvements with virtually each new production run.

Other companies, chief among them Kelvinator and General Electric, added their own improvements in a quest for a share of this obviously lucrative new market. By 1923 Kelvinator, which had introduced the first refrigerator with automatic temperature control, held 80 percent of market share, but Frigidaire regained the top in part by cutting the price of its units in half—from $1,000 in 1920 to $500 in 1925. General Electric ended up as industry leader for many years with its Monitor Top model—named because its top—mounted compressor resembled the turret of the Civil War ship-and with innovations such as dual temperature control, which enabled the combining of separate refrigerator and freezer compartments into one unit. 


Market forces and other concerns continued to drive innovations. Led by Thomas Midgley, chemical engineers at Frigidaire solved the dangerous problem of toxic, flammable refrigerants—which had been known to leak, with fatal consequences—by synthesizing the world's first chlorofluorocarbon, to which they gave the trademarked name Freon. It was the perfect refrigerant, so safe that at a demonstration before the American Chemical Society in 1930 Midgley inhaled a lungful of the stuff and then used it to blow out a candle. In the late 1980s, however, chlorofluorocarbons were found to be contributing to the destruction of Earth's protective ozone layer. Production of these chemicals was phased out and the search for a replacement began.

At about the same time Frigidaire was introducing Freon it also turned its attention to the other side of the mechanical refrigeration business: air conditioning. Comfort cooling for the home had been hampered by the fact that air conditioners tended to be bulky affairs that had been designed specifically for large-scale applications such as factories, theaters, and the like. In 1928 Carrier introduced the "Weathermaker," the first practical home air conditioner, but because the company's main business was still commercial, it was slow to turn to the smaller-scale designs that residential applications required. Frigidaire, on the other hand, was ready to apply the same expertise in engineering and manufacturing that had allowed it to mass produce—literally by the millions—the low-cost, small-sized refrigerators that were already a fixture in most American homes. In 1929 the company introduced the first commercially successful "room cooler," and a familiar list of challengers—Kelvinator, GE, and this time Carrier—quickly took up the gauntlet. Window units came first, then central whole-house systems. Without leaving home, Americans could now escape everything from the worst humid summers of the Northeast and Midwest to the year-round thermometer-busting highs of the South and desert Southwest.

At about the same time that both refrigeration and air conditioning were becoming significantly more commonplace, both also went mobile. In 1939 Packard introduced the first automobile air conditioner, a rather awkward affair with no independent shut-off mechanism. To turn it off, the driver had to stop the car and the engine and then open the hood and disconnect a belt connected to the air conditioning compressor. Mechanical engineers weren't long in introducing needed improvements, ultimately making air conditioning on wheels so de rigueur that even convertibles had it.

But as wonderful as cool air for summer drives was, it didn't have anywhere near the impact of the contribution of Frederick McKinley Jones, an inventor who was eventually granted more than 40 patents in the field of refrigeration and more than 60 overall. On July 12, 1940, Jones—a mechanic by training but largely self-taught—was issued a patent for a roof-mounted cooling device that would refrigerate the inside of a truck. Jones's device was soon adapted for use on trains and ships. Hand in hand with Clarence Birdseye's invention of flash freezing, Jones's refrigeration system made readily available—no matter what the season—all manner of fresh and frozen foods from every corner of the nation and, indeed, the world.

Small but incrementally significant improvements continued as the century unfolded, making refrigeration and air conditioning systems steadily more efficient and more affordable—and increasingly widespread. The range of applications has grown as well, with mechanical refrigeration playing a role in everything from medical research and computer manufacturing to space travel. Without, for example, the controlled, air-conditioned environment in spacecraft and spacesuits, humans would never have made it into space—or walked on the Moon—-even with all the other engineering hurdles overcome. But most of us don't have to go quite so far to appreciate the benefits of keeping cool. They're right there for us, each time we open the refrigerator door and reach for something cold to drink.