While modern air conditioning was born on the factory floor in the early 20th century, by the 1920s and 30s it had become integral to department stores, movie theaters, ships, trains, restaurants and supermarkets. Over time, industrial air conditioning systems became smaller, simpler, and less expensive, eventually entering the residential space as a home appliances.
Today, both industrial and residential air conditioning have become more energy efficient versatile, affordable, intelligent and sustainable.