Efficiency alone almost certainly will not allow us to avoid climate catastrophe, due to the Jevons Paradox: https://en.wikipedia.org/wiki/Jevons_paradox When an activity uses less energy and therefore becomes less expensive, people tend to simply engage more in that activity, until they use more energy than they did before. One reason why is obvious from your attitude here: our culture considers life to be more luxurious and enjoyable when you can do and consume more stuff, and advancing the idea of doing/consuming less is considered backwards and not "useful".

Insulation at the scale needed to avoid climate catastrophe would require a massive international mobilization, along the lines of the Green New Deal and a Green Marshall Plan, to renovate all buildings everywhere before 2050. Sadly the political will to do this seems absent from almost every country, with a couple possible exceptions such as Chile attempting to rewrite their constitution to prioritize climate justice. Basically no countries are approaching even the inadequate Paris agreement targets.

And if you achieved such insulation, without other more drastic changes to our society, people would just run their AC/heat more to reach more luxurious temperatures, and we would not avoid any greenhouse gas emissions.