In the beginning, it wasn’t the heat, but the humidity. In 1902, the workers at Sackett & Wilhelms Lithographing & Printing Company in New York City were fed up with the muggy summer air, which kept morphing their paper and ruining their prints. To fix the problem, they needed a humidity-control system. The challenge fell to a young engineer named Willis Carrier. He devised a system to circulate air over coils that were cooled by compressed ammonia. The machine worked beautifully, alleviating the humidity and allowing New York’s lithographers to print without fear of sweaty pages and runny ink.
But Carrier had a bigger idea. He recognized that a weather-making device to control humidity had even more potential to control heat. He went on to mass-manufacture the first modern air-conditioning unit at the Carrier Corporation (yes, that Carrier Corporation), which is still one of the largest HVAC manufacturers in the world. Air-conditioning went on to change far more than modern printing—it shaped global productivity, migration, and even politics.