… much of the existing carbon emissions. In the face of the long replacement time, focus has shifted to retrofits and upgrades to existing building stock. This would both reduce the … much of the existing carbon emissions. In the face of the long replacement time, focus has shifted to retrofits and upgrades to existing building stock. This would both reduce the … much of the existing carbon emissions. In the face of the long replacement time, focus has shifted to retrofits and upgrades to existing building stock. This would both reduce the …