Analysis of M-EDI and Visual Metrics According to Pendant Lighting Conditions: A Comparison with Flat Panel Fixtures

This study investigates how the mounting height and direct–indirect light ratio of pendant luminaires affect non-visual lighting performance(M-EDI, Melanopic Equivalent Daylight Illuminance) and visual metrics(UGR, uniformity, etc.) in a small office, compared to flat panel luminaires. Relux-based simulations were conducted with horizontal illuminance(Eh) normalized to 500lx. Among the 28 pendant lighting scenarios, 11 met the M-EDI ≥ 250lx criterion; however, 6 were excluded because they required luminous flux beyond the rated 4,100lm. The compliant 5 scenarios showed high Ev/Eh ratios(0.74–0.95) but also high UGR values(25.2–25.6), exceeding the office recommendation(UGR ≤ 19). In contrast, flat panel luminaires did not meet the M-EDI criterion(250lx) but exhibited UGR values that met or neared the threshold. These results reveal a trade-off between visual comfort and non-visual performance, indicating that hybrid lighting strategies combining both luminaire types may be necessary.