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7 Findings and Recommendations CHAPTER 1 largely at the direction of Congress in the FY2009 ARRA funding and the FY2012 appropriations bill. FINDING: A light source need not emit energy at every visible wavelength in order to achieve high color quality (see FINDING: The percentage of matching funds from R&D Figure 1.9). An understanding of the spectral power distribu- grant recipients was 18 percent for FY2011 funds. Ten years tion’s effects on luminous efficacy and the color properties of ago, for FY1999 to FY2001, it had been roughly 40 percent. a light source will enable SSL developers to optimize energy It has declined in the past few years, particularly in the Prod- efficiency while maintaining good color quality. uct Development category. CHAPTER 2 RECOMMENDATION 2-2: The Department of E ­ nergy’s solid-state lighting program should be maintained FINDING: While it is difficult to discern the contribu- and, if possible, increased. tion of public policies on the adoption of energy efficient products, it is likely that a sizable fraction of the decrease in RECOMMENDATION 2-3a: The Department of per capita energy consumption may be attributable to such Energy should seek to obtain 50 percent cost-sharing for policies, judging from a study of changes in energy consump- manufacturing research and development projects, as was tion in California. However, the actual impact of any specific done with the projects funded by the American Recovery policy instrument is difficult to disentangle as is the impact and Reinvestment Act. on any one type of household energy use. RECOMMENDATION 2-3b: As part of the next man- FINDING: Improvements in energy efficiency of light- dated study of the Department of Energy Solid State Lighting ing products have been brought about by a combination of program in 2015, an external review should be conducted legislation, regulation, RD&D funding, consensus standards, to provide recommendations on the relative proportions of industry programs and initiatives, incentive programs, and funding that should be dedicated to core technology, product market forces. development, and manufacturing projects, and what the tar- geted level of matching funding should be in each of these RECOMMENDATION 2-1: The Department of Energy three funding categories. should develop a study to quantify the relative impact of different policy interventions on the benefits of adopting FINDING: DOE’s waiver of Bayh-Dole for projects efficient lighting. funded by the SSL R&D program is discouraging some universities and small companies from participating in the FINDING: DOE has done an impressive job in leverag- program. ing a relatively small level of funding to play a leading role nationally and internationally in stimulating the development RECOMMENDATION 2-4: The Department of Energy of SSL. should consider ending its waiver of Bayh-Dole for SSL funding. FINDING: In recent years, DOE has recently expanded its portfolio to include R&D into manufacturing projects, 106

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FINDINGS AND RECOMMENDATIONS 107 FINDING: A technology-neutral specification for light- FINDING: Other countries are following similar regula- ing would “raise the bar” for energy efficiency without put- tory pathways as the United States in phasing out incandes- ting the government in the position of picking and choosing cent lamps, although at different schedules and with some which technologies should be included in ENERGY STAR®. delays. Rather, those technologies that meet the specified criteria (e.g., luminous efficacy, color temperature, color rendering) FINDING: Disposal of mercury-containing CFL lamps would qualify for ENERGY STAR® labeling. and perceived health impacts are causing concern by some citizens and states. Federal legislators and other actors RECOMMENDATION 2-5: The Environmental Protec- promoting CFL lamps failed to adequately anticipate these tion Agency should develop technology-neutral specifica- perceived risks and concerns. tions for lighting that are based on performance rather than the type of lamp to provide the most objective and even- RECOMMENDATION 2-7: Policy makers should handed standards for energy efficiency. anticipate real or perceived environmental, health, and safety issues associated with solid-state lighting technologies and FINDING: The ENERGY STAR® program provides prepare to address such concerns proactively. useful information to residential consumers on energy efficient lighting products. While the ENERGY STAR® FINDING: The experience with CFLs provides a number program also has a commercial and industrial segment, that of lessons for SSL, including the following: (1) the quality, program focuses on overall building efficiency rather than reliability, and price of initial products will be a critical the certification and labeling of individual products (with the factor in the success and consumer uptake of the product; exception of luminaires in commercial buildings subject to (2) market introduction and penetration take time; (3) manu- federal procurement). Many other government and industry facturers and others should take care not to over promise; organizations address lighting product standards for the (4) consumer education is critical; and (5) ENERGY STAR® commercial sector. and other credible performance standards can play important roles in raising quality and confidence. FINDING: The EISA 2007 requirements for phasing out inefficient lighting have sparked significant resistance CHAPTER 3 by some legislators, states, and citizens in advance of the implementations of the requirements. FINDING: LEDs and OLEDs are complementary lighting sources that can together offer a wide range of lighting solu- FINDING: Given the currently available lighting tech- tions. OLEDs can provide large-area diffuse lighting, while, nologies, LPD allowances for commercial buildings have in the same venue, LEDs form intense point sources, useful reached their practical lower limits, according to lighting for spot illumination and downlighting. The committee finds professionals. In the long term, SSL may permit LPD allow- value in supporting rapid developments in both technologies, ances in building codes to be reduced further. because they both represent large possible markets, new applications, and tremendous energy savings. FINDING: Minimum building energy standards and model codes are steadily improving. Nevertheless, their adop- FINDING: LED and OLED efficiency and performance tion, as well as uniform and effective enforcement of adopted are still limited by fundamental materials issues. Improve- energy codes, would result in significant energy savings. ments in efficiency at the device and materials level, as targeted by the Department of Energy (DOE) SSL roadmap, FINDING: Model energy codes for residential buildings will have a “lever effect”—influencing the design, perfor- only address the efficacy of light sources, not their number mance, and cost of the luminaires. Therefore, improvements or their use. The approach taken by the California residential in efficiency and performance of the entire SSL system are energy code may be more likely to improve energy efficiency. linked to further fundamental investigations in core technol- ogy on emitter materials. FINDING: Non-regulatory incentive programs may play an important role in the adoption of energy efficient lighting FINDING: Current LED dies used in SSL lighting suffer technologies. from inhomogeneities in the light output, color, and operat- ing voltage that necessitate “binning” (hence testing) of dies RECOMMENDATION 2-6: The Department of Energy, from a single wafer. This variability severely constrains the in consultation with the Department of the Treasury, should yield of the manufacturing process and raises the cost of conduct a study to determine the effectiveness and impacts of the technology. These inhomogeneities are in turn related to incentive program designs in fostering adoption of efficient fundamental materials and materials growth issues. lighting technologies.

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108 ASSESSMENT OF ADVANCED SOLID-STATE LIGHTING RECOMMENDATION 3-1: The Department of Energy low-cost GaN substrates. While realization of low-cost GaN should continue to make investments in LED core technol- substrates is not assured, the potential payoff of this research ogy, aimed at increasing yields, and in fundamental emitter is immense. research to increase efficacy, including improvements in the controlled growth and performance of the emitter material. RECOMMENDATION 3-4: The Department of Energy DOE should carefully consider the range and depth of fund- should make a long-term investment in the development and ing in its portfolio of investments in these areas, given the deployment of gallium nitride substrates. existing technological challenges, in order to determine how the targeted goals of device performance can indeed be met. FINDING: LED efficiency and performance is still lim- ited by materials issues. Improvements in efficiency at the FINDING: Efficient operation of LEDs depends on a device level, as targeted by the DOE SSL roadmap, will have number of critical factors related to materials defects, struc- a “lever effect,” influencing design, performance, and cost of ture, and strain. Such factors not only limit device efficien- the luminaires. Improvements in efficiency and performance cies, but also lead to thermal and current droop; all have a are linked to further fundamental investigations in core tech- major impact on the cost and performance of LED lighting. nology on emitter materials. FINDING: The color output of LEDs is extremely sensi- RECOMMENDATION 3-5: The Department of Energy tive to the control of materials composition and thicknesses should continue to make investments in light-emitting diode of the LED structure, which in turn are influenced by the core technology and fundamental emitter research. Its control of the MOCVD growth process. port­olio of investments in these areas should be extensive f enough to ensure that the targeted goals of device perfor- FINDING: A number of approaches have successfully mance can indeed be met. been used to achieve and modulate color rendition for LED lighting. Phosphor-converted and color-mixed LEDs show FINDING: A number of promising approaches have been promise but face different challenges. The ultimate choice developed to increase outcoupling efficiency. of approach will depend on a multiplicity of issues regarding sensitivity of color control, efficiency, reliability, manufac- RECOMMENDATION 3-6: The Department of Energy turability, and cost. should focus on efforts that result in significant light out­ coupling enhancements for OLED that are low-cost to RECOMMENDATION 3-2: The Department of Energy implement and are independent of both wavelength and has provided excellent guidance in its roadmap targets for viewing angle. both phosphor-converted and color-mixed light-emitting diodes. Core investment in these technologies should be con- FINDING: OLEDs show a decrease in efficiency as the tinued, with consideration for promising new technologies current is increased. This results in a reduction in efficiency (e.g., quantum dot layers replacing phosphors). at high brightness. FINDING: Production-scale MOCVD growth of LEDs is RECOMMENDATION 3-7: The Department of Energy a complex process. The uniformity and yield of the structures should support research to understand the fundamental grown (and hence of the optical performance of the LEDs) nature of efficiency droop at high currents in organic light- is strongly and negatively affected by small variations in the emitting diodes and to seek means to mitigate this effect MOCVD growth process. The thermal and lattice mismatch through materials and device architectural designs. between substrate and overlayer exacerbates the sensitivity of the growth process. Further difficulties of growth con- FINDING: The lifetime of OLEDs is very sensitive to trol are anticipated with use of substrates with increased extrinsic factors such as exposure to air and moisture. The diameter. low-cost fabrication of large area OLED lighting sources requires a high degree of fabrication competency that can RECOMMENDATION 3-3: The Department of Energy ensure package hermiticity along the entire large package should fund research to develop instrumentation for in situ periphery and scavenge excess water and oxygen that might monitoring and dynamic control of the metal organic chemi- have been enclosed during the package manufacture. cal vapor deposition growth process. RECOMMENDATION 3-8: To create a highly envi- FINDING: Significant improvements in LED efficiency, ronmentally robust organic light-emitting diode (OLED) yield, and reliability are possible by using GaN substrates lighting technology, the Department of Energy should invest and latticed-matched epitaxial growth processes. Currently, in materials and packaging technologies that make OLEDs there are no viable techniques for producing high-quality, resistant to degradation over their long operational lifetimes.

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FINDINGS AND RECOMMENDATIONS 109 In particular, important areas for investment include finding the Department of Energy should direct studies for determin- low-cost means to eliminate glass as a primary package ing what chemical structural combinations lead to the most constituent, devising molecules and device architectures robust materials sets. Fundamental studies of the degradation that are resistant to degradation on exposure to atmo- mechanisms should be carried out both at room and elevated sphere, and developing sealing technologies that are fast, temperatures. Research on understanding contact and ambi- precise, and robust to bending. ent degradation routes and their minimization should also be supported. FINDING: OLEDs are area light sources, and their rise in temperature, even at the highest drive currents (and hence FINDING: Increased outcoupling remains the single brightness), is minimal. This is a major distinction from most beneficial route to increasing device efficiency from the LEDs, which are intense point light sources and, hence, oper- current 100 lm/W to nearly three times that value. ­Methods to ate at high temperatures that require extensive heat sinking achieve this should be inherently very low cost and deploy- and care in their installation. Nevertheless, OLED opera- able over very large areas, even in the context of roll-to-roll tional lifetime is very sensitive to temperature increases. manufacture. The outcoupling technology should have As the room temperature rises, the OLED lifetime can be the additional attributes of being wavelength and intensity expected to be noticeably decreased. independent, and the light source should exhibit no color shifts as the viewing angle is varied from normal to highly RECOMMENDATION 3-9: The Department of Energy oblique. Clearly, a viable outcoupling technology should not should support the pursuit of material sets and device archi- otherwise impact or degrade OLED performance. tectures that would increase the useful operational lifetimes of high-intensity white organic light-emitting diodes. CHAPTER 4 FINDING: This is potentially the single most important FINDING: While the majority of LED products in the metric to meet in OLED lighting. It requires simplification marketplace have better luminous efficacy than traditional of device structure, use of ultralow-cost substrates such as lighting technologies, for many of them, other quality factors, metal foils, development of replacements for costly transpar- such as useful life, color appearance and rendering proper- ent anodes (current technology is indium tin oxide), low-cost ties, beam distribution, flicker, and noise, may be inferior to encapsulation technologies, and so on. Also, investment traditional lighting products. Even though the optimistic view in equipment infrastructure is essential for the success of is that energy has been saved by using SSL technologies, if low-cost, manufacturable products. In-line vacuum deposi- other factors such as system life, lamp to lamp color variation, tion sources, roll-to-roll processes on flexible substrates, glare, flicker, and dimming, do not meet user expectations, ultrahigh-speed organic vapor phase deposition, and in situ they could slow down market adoption of SSL technologies. encapsulation techniques will all require substantial infra- structure development. FINDING: LED efficacy strongly leverages cost, physi- cal size, and weight of SSL luminaires. RECOMMENDATION 3-10: The Department of Energy should aggressively fund the development of all RECOMMENDATION 4-1: The Department of Energy possible routes leading to significant (100×) cost reduction should place a high priority on research directed at increasing in organic light-emitting diode lighting sources. the efficacy of LEDs. FINDING: Extending the lifetime of blue ­phosphorescent FINDING: OLEDs are typically low-intensity, large-area OLEDs is a primary area where investment will have substan- lighting sources. However, numerous applications require tial payoff. It involves a combination of advances in the devel- more intense, specular lighting as afforded by LEDs. The opment of new materials, device architectures, encapsulation, lifetime of OLEDs are negatively impacted by high currents and contact technologies, as well as a fundamental advance used to generate high brightness. in the understanding of degradation processes. Interactions between the phosphor and the conductive host will have an RECOMMENDATION 4-2:  The Department of Energy influence on mitigating efficiency droop, or the de-excitation should invest in research that can lead to small area but high- of the molecules in the OLED. The mechanisms for thermally intensity lighting systems with organic light-emitting diode induced degradation also require clarification. Encapsulation for use in directional illumination applications. compatible with flexible, lightweight substrates is also an important area of development. FINDING: Because of the large number of different ways to construct an LED lamp, industry has recognized the RECOMMENDATION 3-11: Given the interactions need for some levels of standardization and has organized to between the phosphor and the conductive host molecules, develop such standards.

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110 ASSESSMENT OF ADVANCED SOLID-STATE LIGHTING FINDING: OLEDs are still in their infancy. While the FINDING: The power requirements and flexible physical driver electronics may have many similarities to that of configurations of SSL make attractive the concept of a new LEDs, there are some essential differences in their operating dc building lighting infrastructure. performance because of the large capacitive load presented by OLEDs. RECOMMENDATION 4-6: The SSL industry should collaborate with other industries such as building materials FINDING: LED replacements for incandescent lamps and construction to explore the challenges and potential may not work with all existing control infrastructure, espe- benefits of developing and adopting standards for a new dc cially dimmers. electrical infrastructure. RECOMMENDATION 4-3: Industry should develop CHAPTER 5 standards for LED drivers and future generations of lighting controls that will ensure that all LEDs that are designated FINDING: Replacing incandescent or fluorescent lamps “dimmable” work well with all new dimmers in the future. with LED lamps provides an opportunity to greatly reduce In the meantime, SSL products should indicate on their power load and increase lamp life. They can also turn on labels that they may not function correctly with presently instantly and are able to dim. The market for these lamps installed controls. will only expand as the light and color quality improve and the costs are reduced. FINDING: Additional standards or revisions to stan- dards are needed to resolve unknowns that will otherwise FINDING: The best LED applications take advantage of be left to consumers and other lighting decision makers to the directional light put out by LEDs, such as downlights, resolve, specifically test procedures and/or de-rating factors wall washers, and grazing and accent lighting. that account for higher temperature environments, where performance may vary from LM-79 data, and alternatives to FINDING: Omni-directional LED lamps are not as LM-80 that can predict whole product life more accurately. efficient as linear fluorescent lamps. In order to become a In the case of the latter, research is under way to develop test viable replacement alternative for linear fluorescent lamps, procedures to predict whole product life more accurately. SSL products need to improve efficacy, become more omni- directional, and reduce initial cost in order to compete with RECOMMENDATION 4-4: (a) Manufacturers should fluorescent lamps. publish data for photometric quantities and life per industry standards and de-rating factors for use in typical applications. FINDING: SSL must have power quality standards to (b) IESNA should develop a test procedure to predict whole mitigate against high THD, low PF, and repetitive peak cur- product life more accurately. (c) ANSI should revise the color rent issues. binning standard to ensure imperceptible color differences between two adjacent light sources. FINDING: New dimmers must be able to operate LED luminaires and lamps smoothly without perceptible flicker FINDING: There are existing standards for THD and and should be available to dim from 100 percent power to PF for electronic ballasts for linear fluorescent lamps, but 1 percent power. at present there are no such residential standards for LED d ­ rivers that are external to the lamp. Standards for low- FINDING: Industrial applications of SSL products will wattage, integrally ballasted CFLs with medium screw-bases require higher light output for ambient lighting because of in residential applications allow low PF and high THD. their use in high ceiling applications. RECOMMENDATION 4-5: For external solid-state FINDING: Discomfort or disability glare can be an lighting drivers in general, industry should adopt the same issue with directional LED luminaires. Luminaires must be total harmonic distortion and power factor standards that are designed so as not to increase glare potential compared to in place for electronic ballasts for linear fluorescent lamps. their HID counterparts. Industry should revisit the standards for low-wattage medium screw-base lamps to determine their impact on power qual- FINDING: LED white light products produce light in ity before applying them for light-emitting diode lamps, spectral regions that may create environmental and health and these standards should match those for commercial and concerns. These concerns should be recognized in the design industrial applications. and application of LED luminaires.

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FINDINGS AND RECOMMENDATIONS 111 FINDING: Exterior lighting is a prime candidate for FINDING: The labels designed by DOE and FTC for early adoption of SSL because of the lower lighting levels lamp packages help consumers better understand the char- required in such applications and the optical control, long acteristics of the product they are purchasing, but important life, and dimmability characteristics of SSL. information is missing from the labels that would help consumers to better differentiate products and assign value FINDING: Were OLEDs to become commercially to the products. viable, they would provide an opportunity to change the form factors of how luminaires are designed with smaller RECOMMENDATION 6-3: The Federal Trade Com- sizes, less material, and fewer physical constraints and offer mission should conduct a study in 2014, 2 years after an ability to change from traditional-looking luminaires to introduction of the label, to determine the effectiveness of internally lighting surfaces and materials. the labeling and whether it could be improved by additions and/or changes. FINDING: Replacing existing incandescent lamps with LED lamps in existing luminaires may under certain condi- FINDING: The move to new lighting is changing the tions cause the LED to overheat. Examples include down- entire vernacular used for lighting. It is going to be critical to lights adjacent to insulation or in enclosed luminaires. This is label products in a clear way and educate retailers, consum- true also of the use of SSL in industrial applications having ers, lighting designers, and contractors on the opportunities higher ambient temperatures. LED lamp heat management and challenges with these new lighting technologies. To this needs to be addressed for all such applications. end, EISA 2007 authorized $10 million a year to advance public awareness, but this money has not been appropriated. FINDING: Many LED lamps currently available do not have the same light output and color rendering properties as RECOMMENDATION 6-4: The Department of Energy incandescent lamps. SSL products with improved light out- and lamp manufacturers and retailers should work together to put that are color consistent from product to product will be ensure that consumers are educated about the characteristics needed for the public to readily accept these as replacements and metrics of the new technology options. for incumbent lighting technologies. RECOMMENDATION 6-5: The Environmental Protec- FINDING: There is no standardized method for measur- tion Agency in conjunction with the Department of Energy ing the lifetime of SSL products. should conduct a study to understand the environmental impacts of SSL and to determine potential disposal strate- FINDING: The CRI does not always yield results that gies, if necessary, that should be developed as SSL deploy- predict or evaluate performance well, so manufacturers can- ment develops. not rely on it to guide product development. FINDING: Without appropriate data on consumer light- ing use, it is difficult to establish an appropriate baseline CHAPTER 6 of energy use in lighting and benchmark energy lighting FINDING: To make LED-based luminaires and lamps at efficiency. high efficacies (notionally those exceeding 150 lumens per watt) at prices lower than fluorescents, technological and RECOMMENDATION 6-6: The Energy Information manufacturing breakthroughs will be needed. Administration should collect data on energy demand for lighting through the Residential Energy Consumption Sur- RECOMMENDATION 6-1: The Department of Energy vey, the Commercial Energy Consumption Survey, and the should concentrate its funding on light-emitting diode core Manufacturing Energy Consumption Survey. These efforts technology and fundamental emitter research that have the need to be pursued on a consistent basis and should con- potential to lower costs of solid-state lighting products. sider adding questions that would increase the accuracy and usefulness of the data. In addition, detailed lighting market FINDING: There are currently no industry-accepted characterization based on nationally representative surveys, accelerated life tests for SSL products, which slows the such as the 2001 Lighting Market Characterization from the development and deployment of new reliable products. Department of Energy, need to be pursued every 5 years. It would be helpful if these surveys are available before this RECOMMENDATION 6-2: The Department of Energy study is updated in 2015. should continue efforts to help develop accelerated life tests for luminaires and LEDs.

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112 ASSESSMENT OF ADVANCED SOLID-STATE LIGHTING FINDING: On a life-cycle basis, warm and cool white FINDING: Government agencies that manage building LEDs are already cheaper than incandescent lighting and will assets can play a larger role in helping the deployment of likely be comparable to that of fluorescent lighting technolo- energy efficient SSL. gies in the near future. For applications where the daily usage is larger than 10h/day, cool white LEDs have now a similar RECOMMENDATION 6-8: The Office of Management consumer cost to CFLs or T12. and Budget should develop criteria for determining life-cycle costs and for including social costs in evaluating energy FINDING: As discussed in this chapter and in previous purchases and incorporating this methodology into agency chapters, demonstration, outreach, and public and industry procurements. education programs are important for widespread adoption of SSL products and can help to avoid the problems encoun- RECOMMENDATION 6-9: Government and industry tered during the introduction of CFLs. should continue to provide support in a cooperative and com- prehensive manner to upstream, midstream, and downstream RECOMMENDATION 6-7: The Department of Energy market actors and should support market activities evenly. should take a leadership role, in partnership with the states and industry, to examine and clearly identify opportunities for demonstration, outreach, and education so that its activi- ties in support of SSL deployment are most valuable.