Road Lighting Energy Reduction Through Transition From Hps Lamps to Leds and Dimming a Case Study of Uganda Street, Merkato, Addis Ababa

Abstract

Street lighting systems are integral to modern cities and greatly enhance their ability for nighttime business continuity, provide pedestrian and driver safety through improved road visibility, deter criminal elements and is a source of pride for the communities in which they are installed. Despite their many benefits, city authorities incur huge expenses in establishing and maintaining street lighting systems. The energy costs are even more punitive where HPS lamps are installed. Many interventions have been sought in a bid to reduce the street lighting energy consumptions: switching off streetlights has proved to negate the very essence of their installation since many accidents have resulted. The project has evaluated the energy saving benefits of replacing HPS with LED luminaires, on Uganda Street, a 1.35km road in Merkato, Addis Ababa. Dialux evo has been used to evaluate the lighting performance under HPS and LED lighting cases with reference to CEN13201-1 and EN13201-2. Dimming of LED luminaires has been employed to further evaluate additional energy savings. Road night-time traffic data has been utilized to recommend a suitable dimming schedule. Through transition from HPS to LED lighting, 48.52% energy savings have been realized; by further dimming the LED luminaires, a total of 75.98% savings were obtained. A six-year payback period was computed with a positive net present value. The study provides confidence to city authorities that transitioning from HPS to LED lamps significantly lowers their energy consumption burden and is a key measure of reducing their overall maintenance and annual energy consumption costs. Key Words: HPS, LED, Energy Savings, Dimming and Lighting Performance.