As our world gets depleted and stripped of its resources, we use the materials for the essential, the practical and the needless. The building and construction sector is responsible for a big percentage of carbon emissions. And as we try to reach a sustainable future renouncing the needless and the pointless follows on all scales:

Do we need all the non essential infrastructure? The cleanest and most sustainable buildings and infrastructure are the ones that are not built so we should start at the very beginning of the planning.
Do we need the biggest and the grandest? Size and economy of buildings and infrastructure is easy to define. The floor-plans should be rational and responsible.
Do we need all the small things? The extra drywall, the concrete divider, the extra door? Leaving the nonessential parts so we can use the essential things more freely.

Renouncing the needless on all scales should be the first step and the fastest and easiest way to a more sustainable future.