The Night Path Lit: Lighting the Bed-to-Bathroom Route Priced Against Fall Risk

A design and pricing model for low-level, motion-triggered path lighting on a stated 7.0 m bed-to-bathroom route. Trip hazards are treated as detection problems whose required floor illuminance rises with age (governing requirement 3.40 lux at age 75). The proposed scheme (5.0 lux bedroom/landing, 7.5 lux bathroom, five skirting-level 2200 K fittings, whole-route trigger, capped at 10 lux to protect dark adaptation) reduces the modelled share of trips with at least one governing hazard undetected from 100.0 per 100 in the dark to 35.8 per 100, at an installed cost of $248.00 and $0.72 per year running cost, while a single $9.00 bathroom-only plug-in night-light leaves the share at 99.9 per 100. SIMULATED, NOT MEASURED: this paper computes illumination adequacy under stated assumptions, not epidemiology; it has no fall-rate data of its own.