Energy Consumption. Rated Life. Environmental Considerations

Transcription

1 Energy Cnsumptin When cmparing LED t metal halide street lighting, there is typically a 50 percent energy reductin with cmparable light levels. Fr example, a 250-watt metal halide fixture wuld typically be replaced by a 125 t 150 watt LED fixture. Rated Life While the mst efficient pulse-start metal halide lamps are rated fr 25,000 hurs, LEDs are rated fr mre than 100,000 hurs f useful life. Envirnmental Cnsideratins Metal halide lamps cntain high amunts f mercury and thus have assciated dispsal cncerns. LED fixtures cntain n mercury r lead, and are restrictin f hazardus substances (RHS) cmpliant. Lumen Maintenance At the beginning f a metal halide lamp's peratin, it puts ut a high quantity f useful light. By the end f its rated life, the lamp is dwn t abut 60 percent f its riginal light utput. Nt nly d LEDs last lnger, but at the end f their rated life they are still prducing mre than 90 percent f their riginal light utput. Start/Restrike Time A metal halide lamp takes anywhere frm fur t six minutes t warm up and emit light, and even lnger t restrike if pwer is temprarily lst. LEDs are instant n, meaning they take n time t warm up. 1

2 Lighting prject: LED Lighting (after) befre

3 * Light utput is the same in bth light surces When cnsidering all f the factrs that affect system efficiency, LEDs prvide a clear advantage ver HID lamps. Here is a summary cmparisn: HID lamp: Surce efficiency is typically 120 lumens/watt r higher. Hwever, lsses frm trapped light, prtective cvers and lenses, inefficient ballasts and unfavrable perating temperature typically result in a measured system efficiency f 30 lumens/watt r less. LEDs: Surce efficiency can be 100 lumens/watt r higher, depending n the type and manufacturer f the LED used. There are n lsses frm trapped light due t the fcused utput f the LED, and secndary ptics and prtective cvers generally reduce utput by nly 25% r less. LED pwer drivers are als mre generally efficient than HID ballasts, and reduce system efficiency by 10-15%. Hwever, even when efficiency reductins due t high perating temperatures are included, LED system efficiency ften remains abve 50 lumens/watt r higher. 3

4 Lumen Depreciatin & Useful Life A secnd imprtant factr invlved in cmparing the efficiency f LEDs t traditinal lamp surces is accunting fr the lumen depreciatin f bth surces. HID surces, especially metal halide, suffer frm substantial lumen depreciatin ver relatively shrt perids: High Pressure Sdium Metal Halide Lumen Depreciatin 20% 50% Maximum Useful Life (Hurs) 24,000 6,000-10,000 Nte: The data abve reflect typical perfrmance and are intended fr illustrative purpses. Yu can enjy higher LED system efficiency fr many mre years than traditinal surces, and pstpne cstly maintenance required t change dim r failed traditinal lamps! 4

5 The Results: LED vs. HID Lighting Efficiency Higher system efficiency and slwer lumen depreciatin cmbine t prvide substantially higher verall efficiency with LEDs cmpared t HID surces. Fr example, the chart belw shws the expected perfrmance f a 100 watt MH street light versus a cmparable the Care Transenergy LED Light Engine: As shwn in the chart abve, the lumens per watt prvided by Care Transenergy LED Light Engine decline gradually ver a lng perid. Hwever, the lumen utput f the equivalent HID lamp declines much mre rapidly, and the HID lamp must be repeatedly replaced during the same perating perid. 5