Changes

Air conditioning became the main innovation for modern cooling. In 1902, Willis Carrier invented the air conditioner, with the first machine he invented also able to control humidity. Carrier used his knowledge of heating objects with steam and reversed the process so that objects became cool. Stuart W. Cramer coined the term air conditioning, where his device used water and "conditioned" it so that the moisture would then be used to create cold air. The first house to have air conditioning was built in 1914, which was built in Minneapolis. David St. Pierre DuBose soon after created the first home with central air conditioning, by creating ducts throughout the house that would take the cold air from the air conditioning unit and blow it around the house. Refrigerators were also used in homes in the 1910s, with the first home refrigerators invented by Fred W. Wolf of Fort Wayne, Indian. Although refrigerators did not cool the home, they did allow people to store cold drinks and food, which helped to cool them during the hot summer months. In 1945, the portable air conditioning unit was created by Robert Sherman, allowing window units to be easily made and installed in older homes that did not have air conditioning. In the 1950s, central air conditioning began to become more common and throughout much of the United States window units and central air conditioning became common.