The Future of LED Lighting Dr. Kevin Dowling, PhD Chair - NEMA SSL Committee Chair - IES TPC SSL Committee Board - Lighting Research Office (LRO) Next...
The Future of LED Lighting Dr. Kevin Dowling, PhD Chair - NEMA SSL Committee Chair - IES TPC SSL Committee Board - Lighting Research Office (LRO) Next Generation Lighting Industry Alliance
VP Innovation, Philips Color Kinetics Burlington, MA Montreal, Sept 15 2009
LED History • 1962 First visible LED (Holonyak at GE) • 1960’s Red LEDs (HP & Monsanto) • 1970’s Yellow Green LEDs • 1980’s Higher outputs • 1996 Blue LEDs (Nakamura at Nichia) • 2000 White LEDs • 2008-now General Lighting Sources
Benefits of SSL • Ultra long source life • Low power consumption • Low maintenance • No moving parts • Vibration resistance • No UV radiation • Cool beam of light • Digitally controllable • Fast Response
Performance Trends
Luminous Efficiency (lumens / watt)
200
150
LED
100
White LED
Fluorescent
50
IR Halogen Incandescent
0 1920 Source: Lumileds
1940
Halogen
1960
1980
2000
2020
Haitz’ Law: LED Output Up/ Cost Down Red Flux
100000
20x Increase/Decade
1000
+35% CAGR
100 10 1
10x Decrease/Decade -20% CAGR
0.1 0.01 0.001 1965
Red $/Lumen
1970
1975
Source: Roland Haitz & Lumileds
1980
1985
1990
1995
2000
2005
2010
2015
Cost / Lumen ($ / lumen)
Light Output / Package (lumens)
10000
2020
White Flux (Projected) White $/Lumen Expon. (Red Flux) Expon. (Red $/Lumen)
Trend: Falling Cost of LED Light Cost of Light Incorporates • Lifetime • Source efficacy • Energy cost • Replacement cost • Labor cost
Source: Philips Color Kinetics
Headroom: The Green Valley
Danger of Exaggeration Uses almost no energy!” “Lasts Forever!” This hurts LED lighting Performance must be realistic Example: •
…not as bright as the 40 watts claimed
• I paid 6$, and I think it was mislabeled • The color of the light is more blue/white • I had expected a whiter light.
Specification Games • LED lamp – 3 High-Brightness LEDs – Specified 120 lumen output
• LED data at nominal 40 lumens – Measured for 25msec at 25C – 40 x 3 = 120 lumens
• Lamp not actually measured! • The whole = the sum of its parts
2008 - The Year of Standards • New Standards & Guidelines • Published – – – – – – – – –
Definitions Chromaticity Lumens Lumen Maintenance CA Title 24 (2008) US EISA 2007 mandates Updated ASHRAE 90.1 Updated LEED Energy Star (Luminaires)
Active Organization Involvement
Why LED Standards? Industry and LED customers need – – –
Uniform language & definitions Uniform test methods Laboratory accreditation
Truth. Consistency. Proof. Compatibility.
California Title 24 • California Energy Efficiency Standards for Residential and Nonresidential Buildings • Currently using 2005 standards. 2008 standard now available. • Reduces energy by limiting building lighting power • Allows 1W/ft2 energy use
• http://www.energy.ca.gov/title24/
Why California Title 24?
LEDs in Title 24 2008 Lighting Luminaire Power Rating for LED Lighting
Minimum Luminaire Efficacy for LED Lighting
15 watts or less
40 lumens per watt
15 watts to 40 watts
50 lumens per watt
Over 40 watts
60 lumens per watt
Energy Star for LED Lighting • US program to promote energy efficient products • Issued in September 2008
– Many open meetings, calls, drafts for >2 years • http://www.energystar.gov/ • Requires standards for criteria
Energy Star Criteria • • • • • • •
Luminous Flux Power & Power Factor Efficacy Chromaticity Lumen Maintenance CRI Light Distribution
Standards Update: Photometry • CIE TC2-45 CIE 127-2007 Measurement of LEDs • IESNA LM-79 IESNA Electrical and Photometric Measurements of SSL Products • IESNA LM-80 Approved Method for Measuring Lumen Maintenance of LED Light Sources • CIE TC2-46 CIE/ISO LED intensity measurements • CIE TC2-50 Optical properties of LED arrays • CIE TC2-58 Luminance and radiance of LEDs
Standards Update: Color • ANSI C78.377-2008 Chromaticity of SSL Products • CIE TC1-62 177-2007 Colour Rendering of White LED Light Sources • CIE TC1-69 Color Quality Scale (new CRI)
Standards Update: Eye Safety • IES RP-27 Photobiological Safety • IEC 60825-1-2001 Safety of Laser products – To be superseded by new documents.
• CIE S009 Photobiological Safety • IEEE P1789 - Recommended Practices of Modulating Current in High Brightness LEDs for Mitigating Health Risks to Viewers
Standards Update: Safety • • • • • •
ANSI C82.SSl1 Power Supply ANSI C82.77-2002 Harmonic Emission Limits ANSI C78.09 82 Fixture Safety Specification FCC 47 CFR Part 15 Radio Frequency Devices IEC SC 34A 62031:2008 LED modules - Safety IEC SC 34C 61347-2-13:2006 - Lamp Controlgear – Part 2-13: DC or AC controlgear for LED modules
• IEC SC 34A IEC 62560 Self-Ballasted LED Lamps • IEC SC 34A LED lamps > 50 V - Safety specs • UL 8750 LED Light Sources for Use in Lighting Products
Standards Update: Performance • IEC SC 34C 62384 - DC or AC supplied electronic control gear for LED modules • IEC SC 34A - Performance Standard for LED Lamps
• IEC SC 34A - TS 62504 – Terms and Definitions for LEDs and LED Modules in General Lighting
Chromaticity • ANSI C78.377-2008 • Defines Color Temperature regions • Being adopted by LED mfgs
Chromaticity Specification
Future Binning Specification?
LM-79 - SSL Photometry • Electrical and Photometric Measurements of Solid-State Lighting Products – – – –
Luminous Flux Power Efficacy Chromaticity, CRI, CCT
Luminous Flux
Problems with Heat Effects RGB Fixture
520 500 480 460 440 420
15
30 45 60 75 90 Operating Time (Minutes)
120
LM-79 Absolute Photometry • Traditionally, photometric measurements are separate for lamps and luminaires using different test methods • For many SSL products, LED lamps be separated from luminaires and none of the existing standards for lamps or luminaires are directly applicable to SSL products
LM-80 - Lumen Maintenance • Measuring Lumen Maintenance of LED Light Sources • LED packages, arrays and modules • Measured under controlled conditions • Does not provide prediction or extrapolation of data • New effort for Predication (TM-21)
Lumen Maintenance of Traditional Sources
Lighting Research Center - Rea 2000; Bullough 2003
Why the Long Testing Time? • Typical lamp sources do not last this long – Incandescent - 1000-1200 hours – Halogen - 1000-2000 hours – Fluorescent - 8000-20000 hours
• Issue is confidence in extrapolation
Why 70% (L70)? • IESNA - 30% down becomes a perceptible difference • 30% down is a reasonable basis • Some existing sources exhibit similar L values • L50 can be used for decorative lighting but not for general illumination • Emergency lighting values outside scope
Why L70 • Traditional sources exhibit lumen maintenance issues as well
Color Rendering Index Quality of Light Measure • • • • •
Images: NIST
Uses obsolete color space Samples are low saturation Outdated adaptation formula Non-linear in red region Adversely affects LED scores
CRI Testing
Spectrum Synthesizer or ‘Equalizer’ for Light
Spectrally Tunable Light Source
Spectrally Tunable Light Source
– 22 wavelengths – 2400 HB-LEDs – 400 control channels
Legacy
SOLIDSTATE
TRADITIONAL
Lighting System Architecture: Old and New
49
New Generations of Sockets and Bases
In Process
• • • • • • • • • • •
Lumen Maintenance Prediction CA Title 24 (2011) Binning Light Engines Energy Star (Replacement Lamps) Flicker Dimming Drivers UL 8750 Life Cycle Analysis International harmonization
Future Module & Base Concepts New generation sockets allow – – – – – – – –
Mechanical support Electrical connections Replacements Upgrades Thermal connection Communications & networks Optimized performance New lighting options
Dimming and Compatibility Lam p Efficacy vs. Electrical Dim m ing Percentage Incandescent 80.00
Dimmable CFL eW Par 38 LED
70.00 60.00 50.00 40.00 30.00 20.00 10.00 0.00
100.0%
80.0%
60.0%
40.0%
El e c t r i c a l D i m m i n g P e r c e n t a g e
20.0%
0.0%
DoE Product Testing
DoE Caliper Testing Program • ‘Consumer Reports’ for LED product testing • Objective product performance • Over 120 Product tests • Supports Energy Star • Guides development of testing procedures • www.netl.doe.gov/ssl/
DoE Caliper Testing Program
Labeling • Assure product quality • Provide useful information • Mandate standards testing
Life Cycle Analysis Materials
Precursor Gases
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Wafers
Die
Package
Array
Luminaire
Reactors/Epitaxy Energy
Commissioned by NGLIA Started by DoE, 2008 Substrates
Systems • “The System is the Product” – LED Luminaires – Control – User Experience
System Design Example • • • • • • •
Standard form PAR38 Multi-chip LED Efficient narrow optic 92% efficient power conversion Instant-on and dimmable High power factor Low parts count
Metric
Results
Lumens
800
Power
11.4 W
Efficacy
70 lpw
CRI
>90
CCT
2900K
Efficacy Improvements - Control • Freezer Applications - 92% savings • Sensing + control = greater benefit than LEDs alone
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Meta Systems • Not just fixtures & lighting systems • Lighting Interaction • Systems at Scale – Buildings, Campuses. Cities, Regions
• Smart Grid – Adds monitoring, control and communication to the electricity grid – Improve reliability, increase energy efficiency, and allow generation and storage options
Hospitality
Rustic Kitchen
Retail
Clarks/Bostonian
What to Look for in LED Lighting • • • • • • • •
Reputation Support Engineering Systems thinking Portfolio of products Control solutions Dimmable The Light Itself – Artifacts? – Consistency – Color
