Air conditioning
Modern air conditioning emerged from advances in chemistry during the 19th century, and the first large-scale electrical air conditioning was invented and used in 1902 by US inventor Willis Carrier. The introduction of residential air conditioning in the 1920s helped enable the great migration to the Sun Belt in the United States.
Scroll compressor
Léon Creux first patented a scroll compressor in 1905 in France and the US (Patent number 801182).
Creux invented the compressor as a rotary steam engine concept, but the metal casting technology of the period was not sufficiently advanced to construct a working prototype, since a scroll compressor demands very tight tolerances to function effectively. The first practical scroll compressors did not appear on the market until after World War II, when higher-precision machine tools enabled their construction. They were not commercially produced for air conditioning until 1983 when Hitachi launched the world's first air conditioner with a scroll compressor.