If we're talking about electrical heating, this is only true for resistive heating, which is indeed all "waste heat". But many air conditioners can run in "reve

If we're talking about electrical heating, this is only true for resistive heating, which is indeed all "waste heat". But many air conditioners can run in "reverse cycle" [0], where you're transferring outside heat back in, and is much more efficient, apparently 50% cheaper to run in electricity costs. When you run one of these systems, your New Englander and Arizonan are virtuous to the degree of the difference between inside and outside temperatures. ;) There's even now some combined cycle AC systems which use the extracted heat to generate your hot water [1], sadly not yet available/cost-effective for small residential installations, but they're only off by a factor of 2 now (8kW is the smallest system I've seen, my central air is 4kW). [0] https://en.wikipedia.org/wiki/Heat_pump https://en.wikipedia.org/wiki/Heat_pump [1] http://www.mitsubishielectric.com.au/air-to-water-hot-water-heat-pumps.html http://www.mitsubishielectric.com.au/air-to-water-hot-water-...