> tremendously higher efficiency For heat, yes, but not AC. For example, the Mitsubishi MY-GL12NA is a very efficient mini-split with an EER of 13, but a rand

> tremendously higher efficiency For heat, yes, but not AC. For example, the Mitsubishi MY-GL12NA is a very efficient mini-split with an EER of 13, but a random modern window or through-wall unit (ex: https://amazon.com/dp/B07D8R2V8H/ https://amazon.com/dp/B07D8R2V8H/) will have an EER of ~12.