It happens every year. Temperatures get hot, and so we crank up the air conditioning. That means more electricity from the power grid, more greenhouse gas emissions, more global warming and -- with warmer temperatures -- more air conditioning! There are a few ways to halt this vicious cycle, one of which starts with a makeover for the machine itself. NOTE: This story is reported from California, but applies across the country: If manufacturers sold three kinds of ACs for the country's three main climates, we'd save billions in electricity bills.