Certainly for California. But what about New York for example?

Have a look: http://www.eia.gov/consumption/residential/reports/2009/air-...

// Can't find numbers for Germany, but I can tell you that I don't know anybody who has AC at home. (I'm not a hippie.)

// You know how examples work, right? The data is pretty clear: More than 60% of households in the USA have AC.

Fellow German here.

Summer in New York is significantly warmer than in Germany. Consider for starters that NYC is on roughly the same latitude as Madrid.

Different point but Germans seem to always be up in arms about the American use of air conditioning, and if it's to warm for them they should move to milder climate. Weirdly enough I've never heard anything like it about Nordic countries and heating.

Summer in New York is unbearable, I am originally from Russia, I used to live in New York for many years, 28c degree in New York is nothing like 28c degree in Moscow or 28c degree in San Diego (where I live now). It's very relative, depends on a dryness of the air I guess.

The humidity gets you. Germany isn't nearly as humid as New York in the summer.

Yeah, and one major function of HVAC is to draw humidity out of the air.

July average high in NYC is higher than LA:

https://en.wikipedia.org/wiki/New_York_City#Climate

New York's average high in July is higher than LA's.

edit: and that's without even accounting for humidity