for example single family homes, offices and factories. Based on extensive research, they designated each building type with the make-up of materials that they are typically composed of and used that to estimate stocks across the country. The “materials register”, used together with information on regional demolition and new construction projects, means stakeholders in the building sector can now estimate which materials will be available for recycling as structures are torn down and know how those materials could be used for new construction and renovation projects.

No way in hell this is true for anything that is not federal level building considering how much of a non-working federal state germany is. Also no way in hell they got even a halfway accurate read of “gramps built it with some friends after the war” for the anything of the 50s - 70s single family homes considering materials