If air conditioning did not exist most of the southern United States would be scarcely populated. Houston, TX certainly would not be what it is today.
Before A/C units became common place in office buildings, government offices took a summer vacation for 2-3 months each year.
The first air conditioner to be installed in an office building was in 1902 at a publishing office.
In 1930 trains began to install air conditioners in passenger cars making this mode of travel much more comfortable.
The use of an A/C system can account for 47% of the total energy bill in most homes.
Without the invention of air conditioning there are many curable diseases that would be incurable today, because the invention of their antidotes required steady cold environments to be created.