Abstract—Early-stage structural system selection is a critical yet often underexplored determinant of project cost, construction efficiency, structural performance, and embodied carbon. In the context of Saudi Arabia, the significance of these decisions is intensified by hot-arid climatic conditions, fast-track delivery requirements, and ambitious national sustainability targets under Vision 2030. This study delivers a rigorous quantitative and qualitative comparison of five structural floor systems widely adopted in the Kingdom—reinforced concrete flat slabs, post-tensioned slabs, waffle slabs, precast hollow core slabs, and steel frames with composite decks—using a standardized 1000 m² floor plate with a 9 m × 9 m column grid to ensure consistency. The analysis integrates preliminary design quantities with internationally recognized embodied carbon datasets and is strengthened by sensitivity analyses addressing span variability and uncertainty in carbon factors. The findings demonstrate that post-tensioned and hollow core systems can reduce embodied carbon by up to 55% compared with conventional flat slabs, while steel composite systems offer clear constructability and schedule advantages at a higher environmental cost. By explicitly linking structural efficiency, constructability, and localized sustainability considerations, this paper provides a robust, decision-oriented framework that supports early-stage system selection for large-scale developments in hot-arid regions.

Keywords—embodied carbon, structural systems, posttensioned slabs, hollow core slabs, waffle slabs, Steel composite, hot-arid climate, Saudi Arabia, sustainable construction

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