Combining prior innovations and ideas, Carrier added his own ー related to humidity ー and created modern air conditioning. Tasked with controlling the humidity in a printing plant, because humidity affects paper, he found the connection between humidity and temperature.
Carrier designed equipment to control humidity that also controlled temperature, modern air conditioning. By 1911, he presented the “Magna Carta of Psychrometrics,” the study of gas-vapor mixtures, to the American Society of Mechanical Engineers.
After WWI Carrier’s employer, the Buffalo Forge Company, decided to shutter the air conditioning division to focus on manufacturing. They licensed the patents to Carrier and a team six other engineers who formed, what became over several mergers, the Carrier Corporation.
Early setbacks included the Great Depression and WWII, but they overcame these to eventually dominate the market. Carrier still exists as a division of United Technologies. As of 2019 they remain the world’s largest manufacturer of air conditioning equipment.