It's already available. In the USA there's a efficiency rating called SEER which the federal government mandates new ACs must be at least rated at SEER 13. But

It's already available. In the USA there's a efficiency rating called SEER which the federal government mandates new ACs must be at least rated at SEER 13. But if you want to spend the money you can buy ACs with SEER ratings above 25.