Stadia

[petromax]

...clearly obvious reasons.

Right now, today, if you knock down an occupied and running, albeit inefficient old building and build a new one in its place, even if that uses less energy to heat and/or cool it, you will increase the carbon footprint.

[Waterways]

Right now, today, if you knock down an occupied and running, albeit inefficient old building and build a new one in its place, even if that uses less energy to heat and/or cool it, you will increase the carbon footprint.

It depends on what materials you use. Millions of new homes using 50% less energy reduces emission substantially.

[petromax]

It depends on what materials you use. Millions of new home using 50% less energy reduces emission substantially.

It does not. Energy efficient materials (polyurethane insulants and the like, low-emissitivity glass etc) that reduce life cycle costs have a predominantly high carbon footprint in manufacture and in the case of timber are difficult to sustain. The working of the materials in manufacutre is carbon intensive as is the transport to site and the building processes on site.

The reduction of emissions in new homes only reduces the increase of carbon footrint less than a new home built from high energy materials would. In short, they make a bad situation slightly better. They cannot compete from a carbon point of view with keeping existing buildings with or without upgrading.