LEDs: WADING THROUGH THE HYPE TO GET GREAT RESULTS Naomi Miller, FIES, FIALD, LC Pacific Northwest National Laboratory [email protected] Better Buildings.

LEDs: WADING THROUGH THE HYPE TO GET GREAT RESULTS

Naomi Miller, FIES, FIALD, LCPacific Northwest National [email protected]

Better Buildings by Design 2011

Burlington VT

Efficiency Vermont is a Registered Provider with The American Institute of Architects Continuing Education Systems (AIA/CES). Credit(s) earned on completion of this program will be reported to AIA/CES for AIA members. Certificates of Completion for both AIA members and non-AIA members are available upon request.

This program is registered with AIA/CES for continuing professional education. As such, it does not include content that may be deemed or construed to be an approval or endorsement by the AIA of any material of construction or any method or manner of handling, using, distributing, or dealing in any material or product.

Questions related to specific materials, methods, and services will be addressed at the conclusion of this presentation.

Learning Objectives

By the end of this program, participants will be able to:

Apply LEDs to architectural applications successfully

Understand and use tools and metrics to help with applying LEDs to projects

Understand a process to follow that helps reduce risks when using LED

technology

Discuss flicker and dimming issues with LEDs

Know more about lumens, candelas, CBCP, beam spread, and other light

output metrics

Understand how to use the DOE CALiPer website to evaluate LED products                                                                                                     

Course EvaluationsIn order to maintain high-quality learning experiences, please access

the evaluation for this course by logging into CES Discovery and clicking on the Course Evaluation link on the left side of the page.

The Potential of LEDs is Amazing!

Learn the Lingo of LEDs

Learn the Lingo of LEDs

But, the industry is awash in snake oil . . .

LED Technology

Strategy to increase your chances of success:• Learn the LED Lingo• Be skeptical• Assume product literature is more hype than fact• Learn to read photometric reports and color data

IES LM-79

• Approved method describing procedures and precautions in performing reproducible measurements of LEDs:– total flux, – electrical power, – efficacy (lm/watt), and – Chromaticity

• Absolute photometry, not relative photometry

Electrical and Photometric Measurements of Solid-State Lighting Products

LM-79 Report• Full photometric

testing - Compare to photometric report on similar luminaire or lamp

LM-79 Report• “Sphere testing only” –

Good for color data and light output, but no spatial distribution data

• Lumens important (not just Lumens-per-Watt [LPW])

• Input power for system (not just LED chip)

• .

Lamp Beam Angle

www.ssl.energy.gov15 | Solid-State Lighting Program

Beam Angle

Field Angle

4040° ° FLOOD LIGHTFLOOD LIGHT

Field Angle

Beam Angle

Beam Angle at 50% of CBCP

(2500 cd)

Beam angle at 50% of CBCP

(2500 cd)

Field angle at 10% of CBCP

(500 cd)

5000 cd CBCP

Field angle at 10% of

CBCP(500 cd)

Beam Angle at 50%of CBCP

(2500 cd)

Beam Angle at 50% of CBCP

(2500 cd)

Field angle at 10% of CBCP

(500cd)

5000 cd CBCP

Field angle at 10% of

CBCP(500 cd)

6060° ° FLOOD LIGHTFLOOD LIGHT

Beam angle

ColorThe Problem

Current color metrics are inadequate for communicating appearance and color rendering of white light to the lighting designer, architect, engineer, and consumer

Two sources with same CCT can look very different

The u’-v’ color coordinates track back to the black body locus to determine CCT, even if it’s very green or very pink

Duv tells the designer whether it’s green (>0.006) or pink (<-0.006)

Halogen – 99 CRI 2917K, Duv=0.000

Compact Fluorescent – 82 CRI 2731K, Duv=0.003

LED – 84 CRI, 2881K , Duv=0.000

ColorThe Problem

Long red wavelengths (630 – 700 nm) and saturated colors are under-represented in Color Rendering Index (CRI, or Ra) metric

LEDs look better than their CRI value suggests

Without better metrics, manufacturers will make high efficacy light sources with poor color, slowing the adoption of LED lighting by the designer and consumer

Color Quality MetricsColor Quality Scale (CQS)

Color rendering metric with a nod to color preferences

Uses a set of standard colors more equally positioned in color space

Weights red colors more heavily than CRI does

Doesn’t penalize slight increase in saturation (color contrast)

Rewards slight pink shifts, not green shifts

Produces more intuitive color quality values, esp. for LED

Single metric easier to comprehend and use

Color Quality MetricsImproved CRI (CIECAM06UCS)

Color fidelity metric with no enhancements for preference

Uses traditional set of CRI pastel colors

Does not weight red colors more heavily than CRI

Penalizes any perceived increase in saturation

Calculates values that vary slightly from conventional CRI

Values are not more intuitive for designer unless combined with a special R9 (red) value (i.e. two metrics)

Color Applications where Color Rendering/Preference

matters:

Retail clothing/

Furnishings

Homes

Retail (produce)

Color Applications where Color Rendering/Preference

matters:

Face-to-face communication,

schoolsHospitality

(hotel/spa/restaurant)

Color Applications where Color Rendering/Preference

matters:

Anywhere food is served

Anywhere faces are important

Color Applications where Color Fidelity matters:

Industrial color matching, interior design selectionsFood inspection

Healthcare (jaundice, redness, cyanosis)

ColorConclusions

Color metrics for the Professional Designer/Color Specialist:

SPD

CCT and Duv

CQS for single-number color rendering/preference

Improved CRI (Ra) with Special R9 value, for fidelity

Color

Conclusions

Color metrics for the Engineer/Architect/Consumer:

CCT communicated through graphical scale

CQS for single-number color rendering/preference

ColorConclusions

Energy efficiency standards should include minimum targets for color rendering using Improved CRI with R9 and/or CQS

Standardized luminaire photometry should include color metrics of SPD, CQS, Improved CRI with R9, and CCT with Duv

Flicker Flicker factors for both Visible and Invisible Flicker

Modulation Frequency Modulation Amplitude DC Component Duty Cycle

Light Source Waveforms

Flicker What makes flicker worse:

Duration of exposure (longer is worse) Area of the retina receiving stimulation (greater is

worse) Location in visual field (central is worse because it

projects to a greater area of the visual cortex, even though flicker is less noticeable)

Brightness of the flash (higher luminances are worse; scotopic luminances produce low risk, high mesopic and photopic luminances produce higher risk)

Contrast of the flash with the surround luminance (higher is worse)

Color contrast of flash (deep red is worse)

Flicker Implications of flicker:

Headaches (see Wilkins et al)

Neurological problems including epileptic seizure

Distraction Hazard from strobe effect

stopping or slowing apparent motion of machinery

Impaired visual performance (Veitch et al)

Flicker Applications where flicker matters:

Offices

Classrooms

Industrial spaces

Hospitals/clinicsGeneral lighting

Task lighting

Flicker Applications where flicker is less important:

Accent lighting on artwork

Roadways and parking lotsSports and industrial

lighting on 3-phase electrical system

Flicker Products more likely to flicker:

AC LEDs DC LEDs with poor drivers LEDs dimmed with phase-cut (Triac) dimmers LEDs dimmed with Pulse Width Modulation (PWM)

dimmers

Flicker Conclusions:

Keep an eye out for reliable predictive flicker metrics (Flicker Index and Percent Flicker are both inadequate)

Be aware of applications where flicker might be a health or distraction issue

Check the products you are specifying for flicker, and for interactions between dimmer, driver, and LED product that may produce flicker

• Check CALiPER website for a report on the product and a “Benchmark” comparable technology product. (http://www1.eere.energy.gov/buildings/ssl/caliper.html )

• Do the marketing claims match the performance testing?

Reducing the risk of icky

products…..

Check the CALiPER data

Once you have the numbers and it LOOKS OK on paper…

• See it yourself, more than one sample• Check color rendering on your own skin,

familiar fabrics• Check for flicker• Try dimming it, using the recommended

dimmer and the specified transformer• Check for flicker in dimmed state if you

plan to dim it

Reducing the risk of icky products…..

Check on the life of the product:• What is the life of the chip? Is it replaceable in 3 years?• What is the life of the power supply and driver? Are they

replaceable in 3 years?• How does the client get replacement parts?• What does the client do with the old parts?• Does the luminaire stay clean over life of LED?

If you can, specify the LED product as a system

Put tough performance metrics in your specification to ensure it’s not substituted with an inferior product (Use CALiPER metrics as a good start for these performance specs)

Reducing the Risk….

When doing lighting calculations• Use LLFs based on light output at 40% of useful life

LLF = LLD x LDD x RSDD x BF

For linear fluorescent, LLD (at 40% mean life) = 0.92 - 0.96

What about LEDs? Old LEDs never die…they just fade away.

Reducing the Risk….

LLF = LLD x LDD x RSDD x BF (or PSF)

For fluorescent, LLD (at 40% mean life) = 0.92 - 0.96

For LEDs, LLD (at 40% mean life) = anybody’s guess

Educated guess for better LEDs is LLD = 0.70 – 0.90

Reducing the Risk

Reducing the Risks

Beware: T8 Replacement Lamps, but know that they are getting better with time….

Reducing the Risks…..• Performance of the bare lamp….

– Manufacturer literature claims• 15W / 1500lm / 100 lm/W• Replaces 32 – 45W fluorescent

– CALiPER measurements for bare lamp• LED 16W /~1100lm / 69 lm/W• Fluorescent 32W / 3250lm / 101 lm/W

• And then when it’s in the fixture….– LED T8 CALiPER measurements

• 32W /~1800lm / 56 lm/W– Fluorescent T8 CALiPER measurements

• 69W /~4800lm / 69 lm/W

• Bypassing ballast– Safety?– Shunted sockets? Rewired sockets?– Cost of labor?– Irreversibility?

In summary• See it before you specify it. See two or three. • Do mockups with the LED equipment• Use LM-79 testing for best information on performance• Evaluate lumens and LPW and candela distribution• Check CALiPER for test data. Compare to mfg’s claims.• Consider maintained light output and dirt accumulation in

calculations• Dimming LEDs can be problematic. Reliable dimming

requires extra homework on your product specification.• Specify products from companies you know or whom you

trust, or that have a documented support history• Get a written warranty that includes light output and color

variation

Reducing the Risks

Getting great resultsAnd the good news is….• LEDs CAN do a visually terrific job AND save energy!

InterContinental Hotel Lobby, Howard St. San Francisco.

GATEWAY Project demonstration by DOE/PNNL and PG&E and InterContinental Hotel Group.

HALOGEN

LED

HALOGEN

LED

HALOGEN

LED

LEDHALOGEN

InterContinental Hotel, Howard St. San Francisco (GATEWAY Demonstration)

Registration Desk Area of Lobby• LED lamp replacements:

– (217) 20W Halogen MR16 lamps* in wall grazing, with 6W LED MR16s by CRS Electronics

– (7) 30W Halogen IR MR16 lamps* in downlight task ltg, with 6W LED MR16s by CRS Electronics

– (6) 75W Halogen Par30 shortneck lamps* for floor lighting, with 11W LED Par30 lamps by Philips

* All halogen lamps were originally dimmed from 35% to 85% of full output by the dimming system, depending on time of day.

InterContinental Hotel, Howard St. San Francisco (GATEWAY Demonstration)

Payback assumptions:• 24/7 operation• $50 labor cost to change a lamp• $0.13/kWh melded rate• $60 to $65 LED lamp cost• 25,000+ hours LED lamp life• Analysis over 3 years

Preliminary simple payback is 1.1 years.

InterContinental Hotel, Howard St. San Francisco (GATEWAY Demonstration)

The full GATEWAY demonstration report, includes other hotel spaces

If you want to know more…

• Main DOE website: www.ssl.energy.gov• DOE’s Commercially Available LED Product

Evaluation and Reporting program (CALiPER): www.ssl.energy.gov/caliper.html

• Look for the “Lighting Facts”: www.lightingfacts.com

• ENERGY STAR®: www.energystar.gov• IESNA Standards and Guidelines: www.iesna.org

That’s all folks!

Any pesky questions??

[email protected]

LED TECHNOLOGY AND HOW TO TELL THE GOOD FROM THE

ICKY