Material metabolism of residential buildings in Sweden

Construction  materials  are  used  for  the  expansion  and  maintenance  of  the  built environment. In the last century, construction material stock has increased globally 23-fold. Given the current situation, the accumulated stock can be viewed as a repository of anthropogenic resources, which at the end of life could be re-circulated through the economic system to minimize the inflow of raw materials and the outflow of waste. A major step toward increased material circularity is the development of the supporting knowledge  infrastructure.  For  this  reason,  research  has  focused  on  developing methods intended for exposing the material metabolism, namely, estimating the stocksand flows and analyzing the spatial and temporal dynamics of stocks and flows.
Residential  buildings  comprise  a  large  share  of  the  built  environment. However,  the material metabolism of these structures has remained unknown in many geographical contexts. Therefore, in this thesis, a bottom-up approach is employed to uncover the metabolism  of  residential  buildings  in  Sweden.  This  goal  is  achieved  through  three methodological  steps.  First,  a  material  intensity  database  is  assembled  based  on architectural drawings of 46 residential buildings built within the period 1880–2010 in Sweden. Second,  the  stocks  and  flows  are  modeled  with  spatial and  statistical inventory data  and  the  developed  material  intensity  database. Third,  new  spatial analysis approaches to the stocks and flows are conducted within urban and national boundaries. For the urban context,   material   stock   indicators   defined   at   the neighborhood  level  are  clustered  with  well-known  algorithms.  At the  national  level, eight settlement types are considered to indicate the spatial dynamics. The developed database indicates historical trends in terms of the material intensity and composition for residential buildings in Sweden.
Moreover, the results contribute to  establishing  a  global  database  and,  through  an  extended  international  cross-comparison,  to  the  understanding  of  how  the  material  intensity  and  composition  of residential  buildings  differ  geographically.  Furthermore,  the  stocks  and  flows  are estimated in million metric tons at different administrative boundary levels. Among the six categories considered, mineral-binding materials, such as concrete, comprise the largest  share  of  the accumulated stock.

Finally, spatial  differences in material stock composition  are  depicted  in  urban geography and  nationally, among  the  eight settlement  types. At  national  level, densely  built-up
corridors are  identified,  which should be used for enhancing
material circularity.

This thesis contributes with data source exploration, methodological development, and critical analyses, relevant to researchers, policy makers, and practitioners interested
in a more sustained metabolism of construction materials in the built environment.