This study uses material flow analysis to estimate the material stocks and flows and associated upfront embodied carbon emissions for gravity building structural systems in the United States. Seven scenarios that align with the shared-socioeconomic pathways are conceptualized and used to estimate floor space and structural material demands through 2100. These scenarios consider aggressive, moderate, and low adoption rates of timber-based structural materials. Under all scenarios, total floor space is projected to increase to a maximum upper-bound of 202% (162,187 m²) between 2020 and 2100. The results indicate that the associated increase demand for structural materials cannot be met solely by urban mining of decommissioned buildings. Assuming present-day carbon emissions intensities of structural materials, the average upfront embodied carbon intensity for gravity superstructures in the building stock decreases from 49 kg CO₂e/m² in 2020 to 29 kg CO₂e/m² in 2100 under the scenario with aggressive adoption of timber-based systems.

本研究使用物质流分析来估计美国重力建筑结构系统的物质存量和流动以及相关的前期隐含碳排放。与共享社会经济路径一致的七种情景被概念化并用于估计到 2100 年的占地面积和结构材料需求。这些情景考虑了木材结构材料的激进、中等和低采用率。在所有情景下，总建筑面积预计将增加到 202%（162,187 m ²) 2020 年至 2100 年之间。结果表明，对结构材料的相关增长需求不能仅通过对退役建筑物进行城市采矿来满足。假设当前结构材料的碳排放强度，在该情景下，建筑存量中重力上层建筑的平均前期隐含碳强度从2020 年的 49 kg CO ₂ e/m ²降至2100年的 29 kg CO ₂ e/m ²积极采用基于木材的系统。