A New Illumination Paradigm I

Makarand Chipalkatti

OSRAM Sylvania

Dr. Chipalkatti said that a “shared sense of anticipation” now existed in the field of solid-state lighting and that the symposium was well timed to update the lighting community on current events. At the same time one must have a solid grasp of how to move this interesting phenomenon in science and technology forward into economic reality. One must also know what differentiates the good ideas that languish in the lab from those that become useful features of everyday life.

A truly innovative technology is a “disruptive” influence in that it displaces older technology because of its inherent advantages. The challenge is to understand situations when this has happened before and to understand how to facilitate a similar transition in the field of solid-state lighting.

THE CONTEXT OF ARCHITECTURE

He cited his own ongoing discussions with co-speaker Dr. Sheila Kennedy of Harvard University and the architectural firm of Kennedy & Violich and its efforts to demonstrate this new technology in the context of architecture. He showed a picture of a new kind of structural material: a tile in which was embedded one of Sylvania’s LED “modules,” the term used for a pre-lamp or proto-lamp. This is a new lighting product that is both structural and has a long life as a source of illumination. Such a product could change the dynamics of purchasing, installing, and replacing lighting. This product could be embedded in a structural material because the long lifetimes of LEDs make it possible to think in terms of some degree of permanence.



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Partnership for Solid-State Lighting: Report of a Workshop A New Illumination Paradigm I Makarand Chipalkatti OSRAM Sylvania Dr. Chipalkatti said that a “shared sense of anticipation” now existed in the field of solid-state lighting and that the symposium was well timed to update the lighting community on current events. At the same time one must have a solid grasp of how to move this interesting phenomenon in science and technology forward into economic reality. One must also know what differentiates the good ideas that languish in the lab from those that become useful features of everyday life. A truly innovative technology is a “disruptive” influence in that it displaces older technology because of its inherent advantages. The challenge is to understand situations when this has happened before and to understand how to facilitate a similar transition in the field of solid-state lighting. THE CONTEXT OF ARCHITECTURE He cited his own ongoing discussions with co-speaker Dr. Sheila Kennedy of Harvard University and the architectural firm of Kennedy & Violich and its efforts to demonstrate this new technology in the context of architecture. He showed a picture of a new kind of structural material: a tile in which was embedded one of Sylvania’s LED “modules,” the term used for a pre-lamp or proto-lamp. This is a new lighting product that is both structural and has a long life as a source of illumination. Such a product could change the dynamics of purchasing, installing, and replacing lighting. This product could be embedded in a structural material because the long lifetimes of LEDs make it possible to think in terms of some degree of permanence.

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Partnership for Solid-State Lighting: Report of a Workshop THE TECHNOLOGY S CURVE In contemplating a new technology it may be helpful to look at the technology S curve, which is a rough adoption curve that results from plotting the development of a certain parameter, such as efficiency, against time. When he looked at S-curve data for the first time, Dr. Chipalkatti was startled to find that the products being described were incandescent lamps and fluorescent lamps. Because he worked for a lighting company, the data immediately caught his attention. When he began working on the research and development of organic light emitting diodes (OLEDs) and LEDs, it occurred to him to try to demonstrate how fast this technology was actually moving. He decided to try plotting the progress of solid-state lighting, using the parameter of efficiency against time. He found that the new technology was following the same S-curve pattern as earlier lighting technologies. Then he extended this plot by using all of their optimistic forecasts and actual research that Sylvania and other laboratories had accomplished. He included discussions in symposiums like the current one, where attendees shared their laboratory experiences and projections through the next decade. He said that the response from those performing the R&D was generally optimistic and that the time had come to act, to “make this happen.” A DISRUPTIVE TECHNOLOGY He addressed the question of whether LEDs would be a disruptive technology, and whether their adoption would upset traditional lighting customs. The answer is “yes.” At the same time, however, many incandescent products and other traditional lamps are already being challenged by LEDs. Incandescents, in particular, are inefficient in terms of light output, especially for monochromatic applications such as exit signs. “To some extent the incandescent lamp is akin to taking a log of wood and lighting it up. It just heats something so hot that it produces light.” A solid-state device, by contrast, converts electrons directly to photons without reliance on heating. Rather than using the term “disruptive technology,” Dr. Chipalkatti said that he prefers to describe solid-state lighting as a new technology that will expand the lighting industry, create new concepts in lighting, and extend the concept of lighting in new directions. He used the structural tile again as an example of a function combined with a material that has never been possible before. He hoped that such a possibility would fire the imaginations of users, consumers, architects, and designers to stimulate growth in new directions. Every day, he said, LED technology is leading to new concepts and inventions.

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Partnership for Solid-State Lighting: Report of a Workshop WHY LEDs? Why, Dr. Chipalkatti asked, are LEDs so interesting? First, they are very energy-efficient light sources. They are already more efficient than incandescent lamps and, because 20 percent of electricity use in the United States is related to lighting, energy experts have estimated a potential annual savings of $30-$70 billion in energy costs by 2020. In addition, LEDs as a general rule are very long lasting. Different colors have different lifetimes, but the typical red or yellow LEDs have estimated life-times of about 100,000 hours, or more than 10 years. Even when they reach this lifetime they do not burn out as traditional bulbs do; rather, they begin to lose brightness gradually but remain useable to some degree. Another feature that brings long lifetimes is their robustness. They are solid-state devices; there are no filaments to break or electrodes or glass to shatter. This long lifetime allows people to spread the cost of their lighting system over a much longer period than traditionally possible. Another selling point for LEDs is that they are very reliable devices. Because they can be used in rugged conditions, they are well suited for exterior applications such as traffic lights, where the cost, inconvenience, and even danger of changing a light bulb in the middle of traffic are considerable. Finally, the quality of the light may be adjusted for the user. It is unlikely that a user would want to change from a blue light to red, although this is possible, however more subtle changes may be desirable, such as changing from a warm white light suitable for winter to a cool white light for summer. A NEED FOR BRIGHTNESS . . . He discussed some key indicators of future performance, such as brightness. White LEDs are now capable of 15 to 20 lumens per watt, and are expected to reach the range of 100 lumens per watt or more in the next decade or less. This expectation, he said, was backed by laboratory research by all the companies and government labs in this field. Earlier data indicate that prices and performance of new technologies can improve by perhaps a factor of 20 per decade, and that prices may drop by a factor of 10 per decade. The question that remains is, during the introduction of a new technology, what are the critical “trip wires” that trigger broader use of the technology. In the business this is called the price point. Some people have suggested that about 10 cents per lumen is such a point. For the industry to reach this point as soon as possible a more concerted effort by all major players will be required. . . . AND A NEW LIGHTING INFRASTRUCTURE Dr. Chipalkatti returned to the phenomenon of the disruptive technologies and to how they had been accepted in the past. He said that the advent of the

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Partnership for Solid-State Lighting: Report of a Workshop incandescent bulb and the change to electrical lighting was a far larger technological jump than is contemplated today. The lighting system at the time was run by the natural gas industry, which piped gas to street lamps that were lit every evening by hand. In considering what propelled the replacement of gas lamps it is important to remember that it was not a simple invention. In fact, Thomas Edison was far from the first inventor of an incandescent bulb. Some 20 groups before Edison had worked on this concept for 40 years. How then did Edison’s lamp outstrip all the competitors who had so many years of experience? Because, said Dr. Chipalkatti, Edison had considered the needs of the entire lighting system. He not only kept improving the incandescent material, which is what most people think of as the lamp; but he also worked on the best ways to make a vacuum and to seal the lamp around this incandescent material. Even more revolutionary was the electrical supply system he invented. Edison visualized a system of generators and wiring that would distribute DC (direct current) power to all the neighborhoods around the generator and drive each electric bulb remotely. Of course, the world came to adopt an AC (alternating current) system instead, but if Edison were here today, he would probably feel vindicated because LEDs use direct current. Building a system that consists of a power source and a distribution environment is one of the major challenges that the LED lighting industry faces. A distribution system must consider various elements as building blocks of a system. It begins with a source of power, which reaches a circuit board; an LED is placed on top of that, and optical elements may sit on the LED.1 The end products are modules that have printed circuit boards, lenses, and light guides, all of which give flat-panel effects. WHAT IS HOLDING LEDs BACK? Dr. Chipalkatti listed a few of the applications in which LEDs are being used today, such as traffic signals and signage, but asked rhetorically why applications had not developed further toward low-level lighting for buildings, directional signs along highways, safety signs, decorative signage, and in-ground lights, given the potential for substantial energy savings. Factors that hold back the LED development are that people are not familiar with them, they are expensive, and they are not yet simple to use. One of the great appeals of the incandescent bulb, aside from price, is its universality. One can buy a bulb from any manufacturer and screw it into a socket anywhere; this socket, called the Edison socket or the 1   Secondary optics may help focus the light in the desired direction, which is a significant advantage of LEDs. Most other lighting sources give off light that bounces freely in every direction after emission. LED light can be guided exactly where it is needed, without wastage, thanks to the layer-by-layer structuring of the lamp.

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Partnership for Solid-State Lighting: Report of a Workshop Edison base, has the enormous appeal of convenience, which is not true of LEDs today. The “glue” that holds the elements of an LED distribution system together has yet be developed. This does not mean, he added, that the industry should wait until such a system is available. Dr. Chipalkatti urged that we move ahead continually with the latest technology and understand its strengths and limitations. PSYCHOLOGICAL FACTORS Dr. Chipalkatti also addressed the perceived expense of LEDs, which is “almost a psychological factor.” The energy savings and long lifetimes of LEDs far outweigh their high initial costs. Commercial and industrial users will understand the economies of long-lived lighting, but a typical consumer might look only at the purchase price and stay with a cheaper, less efficient option. This mindset has slowed the adoption of compact fluorescents, for example, even though they, like LEDs, are far more economical than traditional bulbs over the lifetime of the lamp. This attitude can only be modified through extensive educational efforts. Another psychological factor is the reputation of fluorescent lights for brightness, which apparently deliver about 100 lumens per dollar. Even though a typical fluorescent lamp has a brightness of about 8,000 candelas per square meter, it requires a fixture for mounting, where much of its light is lost through internal reflection. The effective light output is closer to 2,000 candela per square meter, or about 25 percent of the gross light output. Such basic misunderstandings can hold back the LED industry to a substantial degree. Traditional fluorescent space lighting has another disadvantage that is not apparent. Ceiling fixtures for fluorescent systems require 8 to 12 inches of overhead space. (Some ceilings do contain other utility structures, but these could well be placed in the wall with proper planning.) Illuminated LED ceiling tiles would require no extra space, so that tall buildings using solid-state lighting systems would have room for an extra floor every 10 or 12 floors. REMOVING BARRIERS The best way to remove barriers based on misunderstandings or faulty premises, he suggested, is to support an industry-academia-government partnership in solid-state lighting. Such a partnership, in addition to the technical advantages of cooperation, would have the visibility and means to better educate the consumer about accepting and understanding this new technology. Some key objectives would be to educate lighting designers and consumers about the value of the technology, develop standard metrics for the lighting industry, and adopt a common vocabulary for lighting functions and products. Standards are particularly important, as industry has learned from such wasteful competition as the struggle between Betamax and VHS videotape. One area in which cooperation is needed is the measurement of light output, connectors,

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Partnership for Solid-State Lighting: Report of a Workshop power supplies, and colors. Already there is an urgent need for uniform world-wide standards for illumination from traffic signals. In the United States, for example, the use of an incandescent traffic-signal standard makes it inherently difficult for local governments to adopt less expensive LED technology. A NATIONAL LIGHTING INITIATIVE The next step, suggested Dr. Chipalkatti, is to build a more formal mechanism for cooperation between industry, government, academia, lighting organizations, and the Optoelectronics Industry Development Association (OIDA), which has been very active in this field. Such a solid-state lighting initiative could complete a realistic roadmap, he concluded, to guide the best ways to implement this new technology and to reinvent the field of modern lighting.

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Partnership for Solid-State Lighting: Report of a Workshop A New Illumination Paradigm II Sheila Kennedy Harvard University Dr. Kennedy, who is both a principal in an architectural firm and a researcher at the Harvard University Graduate School of Design, said that she would talk about the role of design research in the development of solid-state lighting. She began with the point that the efficiency and life span of LEDs will open new markets and unprecedented uses for lighting that will have an impact not only on technology and industry but also on education and culture. It seems clear that the next generation of LED applications will not simply be replacement or substitution products. That is, users will probably not screw LEDs into the traditional Edison base that holds our incandescent bulbs. Solid-state lighting technologies will suggest entirely new sets of materials and ways to deliver and use light that go far beyond what she called the current bulb culture of lighting. She offered several examples of emerging possibilities: A network of LED lights loaded into moveable office or house partitions; User-controlled colors and patterns of light; Recycled lighting (e.g., ultraviolet light that enters a house as sunlight) is absorbed by a curtain in which LEDs are embedded and is re-emitted as colored or white light during the evening. LEDs IN FABRICS . . . Such possibilities may sound fanciful, she said, but collaboration between her group and Dr. Chipalkatti’s group at OSRAM Sylvania had produced some innovative prototypes. One is a fabric bearing luminescent pigments (called a “give-back curtain”) performing dynamically and changing the color of the fabric

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Partnership for Solid-State Lighting: Report of a Workshop over time. Another option is to weave LEDs into rug, curtain, or other soft fabric to create a new medium of light delivery. One might be able to read a book, for example, from the light of a throw-blanket made of this material. The blanket could be bent over to produce more light as it is carried around the house. Thus, design research offers tools to imagine new markets, new product applications, and the implications of this new kind of light for daily life. She suggested that design is not simply an end process but an integral aspect of architecture, one of evaluating and accepting technical parameters and creating new concepts about what lighting can be. . . . AND OTHER BUILDING MATERIALS Involved in Dr. Kennedy’s design research team are people of different levels and skills, including industry leaders, materials scientists, technical people from major manufacturers, professionals, and graduate students. She and her colleagues began by establishing parameters for the design research process: They would plan for systems based on technology that was not yet available. They began by considering the efficacy of luminescence in nature. As an example, she showed a slide that compares the incandescent light bulb with a firefly. The output of an incandescent bulb is about 5 percent light, and the rest is heat; the firefly accomplishes almost the reverse. The significance of this for building design and architecture is that LEDs provide a very cool light that brings into question the principle of incandescence, where light is nearly equivalent to heat. LEDs also offer a miniaturization of light sources. Noting this, the graduate students, even though they were not lighting experts, were able to make a variety of demonstration samples, embedding LEDs into concrete pavers, EL (engineered lumber) plywood, and oriented strand board (OSB). For OSB, which is heavily used in domestic architecture as a flooring substrate, the students found that by slightly changing the composition of the resin binder it would be possible to produce a recycled wood product that gives off light. Returning to the contribution of Edison, she agreed with Dr. Chipalkatti that part of his genius was to devise a system for electrical lighting, but another part was actually to develop a vision that included needs and products. These products were to have high significance for education and entertainment as well as business. Similarly, the development of solid state is likely to be more than a technical exercise. Dr. Kennedy described it as an interdisciplinary scientific-creative endeavor. PROGRAMMABLE BUILDING MATERIALS Dr. Kennedy suggested that a significant new market for LEDs would include large-scale applications in architecture, especially programmable building materials. These might have the ability to transmit light and information by

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Partnership for Solid-State Lighting: Report of a Workshop having performative surfaces that integrate multiple functions. She demonstrated a desktop of EL plywood, which because it is engineered from small bits of wood, can contain strips of electroluminescent lights and electrical connections. Thus the desk surface actually provides light, and small hand-held lights could also be plugged in. The electroluminescent light in the surface absorbs light, “remembers” it, and re-emits it in a different color. This brings the possibility of the intelligent control of light with solid state, as the pixilated points of light familiar from television and computer monitors are actually translated into images and information. Solid-state lighting will potentially be able to perform many functions and behave more like media, transmitting information, changing color, and giving the user a high degree of control over color, intensity, and location. She also described a floor system called a low-velocity floor that consists of shapes of engineered lumber rolled out like wallpaper beneath a thin, compressed plenum, or mechanical surface. Then a cool, thin cushion of air can be introduced to distribute cool air far more efficiently than typical air conditioning blown downward from a ceiling. Another architectural application is a hybrid ceiling that not only creates a pleasant surface to look at but also absorbs sound and provides light. An LED-equipped tile in one lighting configuration could be changed to any other color or ability of light, which indicates a capability of programming architectural surfaces. She showed a picture of a prototype desk no more then 3/4-inch in thickness that used fiber-optic materials to move light and information through its surface. The same could be done in floors and walls by using solid-state lighting modules embedded in thin panels of acrylic that take advantage of the acrylic’s optical properties. Her group has also experimented with thermochromic materials in which light is activated or changed in color by the body temperature of one’s hand. AN IMPORTANT EDUCATIONAL IMPACT “If our culture is going to change from a bulb culture to this new paradigm of illumination, we need to begin that change in terms of education.” Dr. Kennedy described the “incredible value of the public discussion that takes place in the university tradition of sharing ideas.” There is also a benefit in terms of professional partnerships between design research and manufacturers that can be “a very cost-effective method for companies to advance R&D, and opportunities for design professionals to make very significant contributions to technology and culture at the national level.” Finally, she referred to the significance of the work products themselves. Design research, she said, often yields the missing or key idea that is necessary to move thinking to another level. The prototypes that are produced have public value as demonstration tools and promote public familiarity with new technology.

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Partnership for Solid-State Lighting: Report of a Workshop Dr. Kennedy called on industry and government leaders to do four things. Promote new forms of collaboration between the government and the private sector. Implement new partnerships between manufacturers and design programs in universities. Sponsor project-specific collaborations between industry and government leaders and design professionals. Implement incentives for the use of solid-state lighting in the design of public projects. TWO DEMONSTRATION PROJECTS Dr. Kennedy concluded by describing two public projects that have been designed to use solid-state lighting to build public awareness in creative ways. The first, in the theater district of Boston, uses structural glass manhole covers with solid-state lighting technology embedded in them. The second, in New York City, is a commission for seven commuter ferry terminals along the East River to be equipped with solid-state lighting connected to photovoltaic power sources. She advocated the use of such public demonstration projects as incentives to encourage further collaborations between the public sector and the lighting industry.