Environmental Impact Assessment of Smart Daylighting Systems Using LCA and Measured Illuminance

Buildings account for a major share of global energy demand and emissions, prioritizing lighting for efficiency improvements. This study evaluates a daylight-assisted lighting system’s energy and environmental performance through a fully measurement-based approach. Monitored illuminance data were processed within a transparent workflow linking lighting demand to power use, electricity consumption, and life-c ycle greenhouse gas emissions. Energy demand was derived from luminaire efficacy and an illuminated area, while environmental impacts were quantified using an attributional life cycle assessment (LCA) framework consistent with ISO 14040/14044 standards. Use-phase carbon footprints were calculated with regional grid emission factors, and manufacturing, transport, and end-of-life stages were included as background conditions. The results demonstrate that the daylight-aware control strategy achieved an average electricity reduction of 17% (95% CI: 15.7–18.3%) compared to the constant baseline, with the greatest savings occurring in daylight-rich months. When translated into environmental terms, these operational reductions yielded a corresponding ~17% decrease in use-phase CO 2 emissions under a regional grid factor of 0.40 kg CO 2 /kWh. Importantly, the system’s embodied impacts were outweighed within an operational payback period of approximately 18–20 months, underscoring both environmental and economic viability. Sensitivity analyses across illuminance thresholds, luminaire efficacy, and grid emission factors confirmed the robustness of these outcomes. Overall, the study provides a reproducible methodology that directly integrates empirical daylight measurements with life-cycle assessment, clarifying the contribution of smart lighting control to sustainable building design.