Exactly! We need more efficiency, and heat pumps/air conditioners are already very efficient at what they do. Of course further efficiency improvements are welc

Exactly! We need more efficiency, and heat pumps/air conditioners are already very efficient at what they do. Of course further efficiency improvements are welcome, but they are small gains. We need to look at where big gains can be made, and improving the thermal efficiency and air circulation of buildings holds a lot of promise. You don't have to go full passivhaus, even just improved insulation, double/triple-layer glass, sun shades and well-placed foliage to provide shade can net much larger improvements than some tweaks to AC design.