There are some interesting questions about whether we have the carbon, energy and resource budget to tear down old homes and build new ones. Maybe we do, I'm not sure. For example if the new homes are net-zero for running then maybe they're okay. But if they are not or require many decades to pay off from the demolition and construction then this would not be viable.

I disagree that preservation of existing homes is of great importance because a lot of homes were built almost 100 years ago or more and are not fit for purpose (insulation, damp, lack of solar gain or getting too hot in summer).