We need more density. Without density mass transit isn't economical. The lower the density, the more expensive it gets to build and maintain infrastructure. Yet faster-to-build or energy-efficient single-family detached homes will not be an appreciable part of any solution. Low density doesn't scale. And it takes up more land, by definition, precluding that land from being reforested, renewed as grassland, rewilded, etc. "Not everyone wants to live in density" is true, but also doesn't address the above points.