A Human-Centric Framework for Outdoor Trespass Lighting: Eye Corneal Illuminance and Circadian Metrics in Real-World Environments

This study proposes a human-centric framework for Outdoor Trespass Lighting (OTL) that moves beyond conventional boundary-based photopic illuminance metrics toward assessing occupant-level ocular exposure. The framework introduces Eye Corneal Illuminance (ECI) as a physically grounded measure of light incident at the eye. It integrates it with circadian-relevant metrics, including Photopic Lux (PL), Circadian Stimulus (CS), and Equivalent Melanopic Lux (EML). A dual-layer methodology combining source-level photometric analysis with user-level exposure assessment was applied to a real-world outdoor lighting project in Ontario, Canada, using industry-standard simulation tools, IES photometric files, and spectral power distribution data. Sensitivity analyses examined the influence of spectral composition, luminaire geometry, shielding, and spatial configuration. Results show that lighting installations compliant with conventional photopic criteria can exhibit substantially different circadian-weighted exposure characteristics. Melanopic-weighted metrics demonstrated greater sensitivity under low-light nighttime conditions, revealing a divergence between visual compliance and biologically relevant exposure representation. The proposed framework provides a reproducible and practical methodology for integrating ocular and circadian exposure assessment into existing outdoor lighting engineering workflows, supporting the future development of health-informed lighting guidance.