When did the widespread adoption of air conditioning start?

The widespread adoption of air conditioning began primarily after World War II, around 1945. This period saw significant advancements in air conditioning technology and a substantial reduction in manufacturing costs, making it more accessible to the average consumer.

In the years leading up to this, air conditioning was primarily seen in commercial applications and luxury settings. However, as residential units became more affordable and energy efficient, homeowners began installing air conditioning systems in larger numbers. The post-war economic boom also contributed to this trend, as people had more disposable income and sought comfort in their homes.

The other dates mentioned do not align with the historical trajectory of air conditioning's popularity. For instance, while air conditioning technology was invented in the early 20th century, it didn’t become mainstream until the mid-20th century, which is why 1945 is recognized as a pivotal year in the widespread adoption of this technology.