Modern air conditioning was invented in 1902 by engineer Willis Carrier — not to cool people, but to control humidity in a printing plant.
From factories to homes
Movie theaters adopted air conditioning in the 1920s. Window units arrived after World War II, and central air became common in new homes in the 1960s and '70s.
Efficiency leaps
A typical 1970s system ran around 6 SEER. Today's minimum is more than double that, and the best variable-speed systems top 20 SEER.
Frequently Asked Questions
+Who invented the air conditioner?
Willis Carrier, in 1902.
+How much more efficient are new AC units?
A new system can use half the electricity of one from the 1990s or earlier.
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