BERLIN—Natalie Mayer knows why Germans disdain the air conditioner, or the Klimaanlage—literally, climate apparatus.

“People here don’t like air conditioning. They think it’s a waste of energy, it’s bad for the environment, and people say it makes them sick,” said Ms. Mayer, a Californian who has lived abroad for more than a decade, including the last four years in Berlin.

She...