Shedding Light on the LED Hype Commercial Applications This document was specifically prepared to aid utility account managers and their customers. Any.
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Shedding Light on the LED Hype
Commercial Applications
This document was specifically prepared to aid utility account managers and their customers. Any other use of this material (in whole or in part) is not allowed without the expressed written consent of Tech Resources, Inc., 2025 Riverside Drive, Columbus, OH 43221.
Lumens—A measure of the perceived power of light.• Constant output regardless of distance from source
Foot-candle—One lumen of light distributed over a square foot area.• Depends on the distance from the light source• Does not hold for focused fixtures like flood lamps• Can be measured using a light meter
Color Rendering Index (CRI)—A measurement of a light source’s ability to render colors the same as sunlight does.• CRI describes to what degree the light spectrum source
Color Correlated Temperature (CCT)—The apparent/ perceived color of a light source compared to the color appearance of an ideal incandescent light source at a particular temperature, expressed in degrees Kelvin (K). • <3,200K is visually warm or red/yellow (good for reading)
Incandescent ~2,800K
• >4,000K is visually cool or blue (good for inspection) Sunlight ~5,500K
Source: PHOTOWORKSHOP.COM
Lighting Fundamentals
White light is a mix of many different colors across the visible lighting spectrum.
Robert Biard and Gary Pittman, Texas Instruments employees, create "invisible" infrared light-emitting diode (LED) from gallium arsenide (GaAs) in 1961
Nick Holonyak, Jr, a GE employee, creates visible red LED in 1962
Nick Holonyak, JrSource: Wikipedia Commons
How It Works
Semiconductor material acts as a one-way valve• Current only flows from the p-side anode to the n-side cathode
Material doped with “impurities”• Holes created in p-side anode
Boron, aluminum, or gallium
• Free electrons in n-side cathode Antimony, arsenic, or phosphorous
Voltage forces holes and electronsinto the middle p-n junction
Photons of light emitted whenelectrons drop into holes
Material selection determines colors• Different colors require different power
• White is achieved one of two ways Combine RGB (low CRI scores, despite good color rendering) Coat a blue LED with yellow phosphor (high CCT/blue shift)
Very compact and low-profile Nothing to “break” No abrupt failure mode Instant on (no warm-up time required) ENERGY STAR qualified LED lights consume 75%
CALiPER tested four different “drop-in” 4-foot retrofit LED products• Poor LED lumens per watt output• Very narrow LED light distribution• Over $50 per LED lamp
Competition from reflector-rated CFLs from 15 to 26 watts that deliver 720 to 1,300 lumens Directional nature of LEDs is an advantage Removing heat from the can
is a real challenge for R-CFLsand LEDs
Cree LED Lighting LR6 6" LED Recessed Downlight at 12 watts and 650 lumens costs around $100
This document was specifically prepared to aid utility account managers who are working with commercial and industrial customers. Any other use of this material (in whole or in part) is not allowed without the expressed written consent of Tech Resources, Inc., 2025 Riverside Drive, Columbus, OH 43221.