[guard-of-terra]

Maybe it's because in California you don't need as much heat/conditioning as in other places?

We humans use land extremelly inefficiently, we mostly live in places outside of our temperature optimum despite no longer being busy in agriculture.

[santaclaus]

The NY Times suggests that inefficient boilers in old buildings could be the culprit [1].

[1] http://www.nytimes.com/2007/07/15/realestate/15cov.html