Air conditioning
or: a printing press fix for hoodies in July
In 1902 a 25-year-old engineer was sent to a Brooklyn printing plant where the summer humidity kept swelling the paper so the colors wouldn’t line up1, and the machine he built to dry out the air had the cooling effect of melting 108,000 pounds of ice every single day2. Now air conditioners and fans use about a fifth of all the electricity in the world’s buildings, around 10% of all the electricity on Earth3.
How it works, badly
Wait, is that real?
Yes, air conditioning started as a fix for paper, not people.
The swollen paper↩
In 1902, the Sackett & Wilhelms Lithography and Printing Company in Brooklyn, New York, had a humidity problem: paper swelled, colors printed out of line, wavy edges jammed the feeders, and ink dried slowly. Willis Carrier, a 25-year-old engineer, designed a system to control the humidity, and it was installed late that summer.
The melting ice↩
According to Carrier, the company he later founded, the plant’s system had the cooling effect of melting 108,000 pounds of ice a day. Air conditioners work by moving heat rather than making cold: a refrigerant soaks up heat as it evaporates indoors and gives it off as it is compressed and condensed outside.
The electricity bill↩
The International Energy Agency says air conditioners and electric fans use about a fifth of the total electricity in buildings around the world, or about 10% of all global electricity. Without efficiency improvements, it expects energy demand for cooling to more than triple by 2050.
The fine print↩
Carrier’s 1902 machine was built to control humidity for the presses; cooling people came later. The IEA figures come from its 2018 report, and the share has likely grown since. Not every office is freezing, and not everyone in it is wearing a hoodie; it just feels that way.
Sources: Carrier: the invention of air conditioning; IEA: The Future of Cooling
Last fact-checked .