District cradle to grave LCA including the development of a localized embodied carbon database and a detailed end-of-life carbon emission workflow

Abstract

The building industry is one of the main contributors to greenhouse gas (GHG) emissions in today's world. To measure the environmental impacts of GHG emissions, life cycle assessment (LCA) has been increasingly utilized in recent years, and building LCA tries to evaluate the GHG emissions in three main phases including embodied carbon (EC), operational carbon (OC), and End-of-life carbon (EOLC).Most of the studies in this field have dealt with individual buildings as the scope of their research. The literature review showed a significant gap regarding the implementation of the LCA on a wider district-level scale rather than just one building. In addition, most of the studies have only considered landfilling of the waste materials and emissions related to this activity for the whole disposal phase emissions. Therefore, a more detailed analysis regarding the EOLC emission has been carried out to recognize the actual share of this section in the whole building’s LCA.To fill the mentioned gaps, this research has done a cradle-to-grave LCA by utilizing localized building materials' EC emission data, besides an OC emission assessment followed by a detailed EOLC emission analysis for a district in Montreal's downtown. Furthermore, a sensitivity analysis regarding the selection of the best building materials according to their environmental performance has been implemented.The results of this study show that for different retrofitting scenarios of the buildings in a district, among the main building components for renovations (walls, roofs, and floors), walls are responsible for the most significant share of the GHG emissions and between various components of the walls, insulation layers have the most impact on the total embodied, operational and EOLC emissions. Detailed EOLC emission analysis revealed that even after implementing a detailed examination of the end-of-life phase, the share of EOLC emissions within the building's life cycle remains below 10%. Finally, the sensitivity analysis among the insulation layers has illustrated that buildings using foam glass for their insulation layer have the most GHG emissions, and buildings with glass wool have the least amount of emissions.