Life carbon assessment of embodied and operational carbon with view assessment across facade systems in Japanese climate zones

• Life‑cycle carbon of façade systems assessed in three Japanese climates. • Narrow double‑skin façades show higher embodied but lowest total emissions. • Narrow‑DSF balance embodied and operational carbon effectively. • Narrow‑DSF systems enhance outdoor views. Embodied carbon (EC) is mainly associated with construction materials, while operational carbon (OC) arises from energy use during building operation. Reducing OC offers significant long-term environmental and economic benefits. This study examines both the upfront product stage EC and the OC; the upfront product stage EC is assessed by applying a process-based life-cycle assessment (LCA) approach. Simulations for OC and daylight assessments are conducted in three Japanese cities, including Tokyo, Sapporo, and Naha, considering south-, north-, and west-facing orientations. The study compares several glazing systems, including single- and double-pane options (with and without shading), triple-pane glazing, and Narrow and Deep Double Skin Façades (DSFs). The unshaded double-pane system is used as the reference case due to widespread application. Narrow-DSF systems effectively balance embodied and operational carbon. Although embodied carbon (EC) at the product stage (A1–A3) increases by approximately 33%, the results demonstrated the significant influence of climate and orientation on OC reduction. Naha achieved the greatest reduction of 38% on the north façade, Tokyo reduced by 29% on the west, and Sapporo reduced by 33% on the west. Glazing panes with louvers reduce shading closures to between 10% and 30%, and provide sufficient views. Notably, this study found that narrow-DSF performs exceptionally well in warm climates with high cooling demand, making the configuration a promising low-carbon solution that supports both energy efficiency and occupant visual comfort across diverse regions.