Integrative design process for structural optimization: A life cycle assessment-driven approach for sustainable office building design

This study explores the integration of Life Cycle Assessment (LCA) within the sustainable construction of office buildings, focusing on a case study in Jeddah, Saudi Arabia, with relevance to national sustainability strategies. Using a cradle-to-grave LCA framework for structural components, environmental impacts associated with material production, construction, use, and end-of-life phases were evaluated, while operational energy (B6) was assumed to be identical across all design alternatives and therefore excluded from the comparative LCA model to isolate the environmental impacts of structural system optimization. The functional unit was defined as the provision of 10,400 m² of gross floor area of an office building over a 60-year service life, and environmental impacts were assessed using the CML life cycle impact assessment method. The baseline design, featuring a conventional reinforced concrete structural system, was optimized through multiple iterations, including the adoption of functionally equivalent and optimized steel structural systems, the use of high-strength steel, and the incorporation of supplementary cementitious materials such as fly ash. The results show that transitioning from reinforced concrete to the optimized steel-based solution reduced Global Warming Potential (GWP) by approximately 26%, alongside notable reductions in Acidification Potential (AP), Ozone Depletion Potential (ODP), and non-renewable energy consumption. Prefabrication of steel components contributed to reduced construction-phase waste, while material-efficient structural design and recycled steel content further enhanced environmental performance. The integration of Building Information Modeling (BIM) tools with LCA methodologies proved instrumental in enabling iterative design optimizations and informed decision-making. This research demonstrates the value of integrating LCA in the early design process to achieve meaningful environmental improvements. By addressing key impact categories, such as GWP, AP, and Eutrophication Potential (EP), the study demonstrates how iterative optimization and material innovations can significantly lower a building's environmental footprint. The sensitivity analysis further shows the substantial environmental benefits of optimizing steel usage and increasing recycled content. Adjustments in steel quantities by ±10% and variations in recycled content from 0% to 70% revealed significant fluctuations in GWP, with the highest reductions observed in designs utilizing high-recycled-content steel. These findings offer a replicable LCA-driven design workflow for evaluating and optimizing structural systems in sustainable construction, while acknowledging that quantitative outcomes are case and context specific. The outcomes contribute to advancing sustainable urban development and support global efforts to mitigate climate change through environmentally responsible construction.