The National Renewable Energy Lab has Done It! As Lloyd and other sensible people keep pointing out, if our buildings and cities were better designed, we would need a lot less air conditioning, and in many cases none at all. That should be goal #1. But because it's doubtful that's ubiquitous A/C is going away any time soon, it can't hurt to make the technology more efficient (keeping buildings cool is using about 5% of the energy used in the US).