Workshop Presentations and Materials

Several hundred researchers, manufacturers, industry insiders, and interested observers from all over the U.S. and abroad gathered in San Diego January 28–30, 2020, to participate in the 2020 Lighting R&D Workshop, co-sponsored by the U.S. Department of Energy (DOE) and the Illuminating Engineering Society (IES). The annual event has been a cornerstone of DOE Lighting R&D Program planning for the past 17 years, and the 2020 workshop featured expanded track sessions, more than 70 speakers, and over 60 posters displaying cutting-edge research.

The speakers and attendees were a diverse lot that included lighting scientists, manufacturers, engineers, contractors, architects, academics, distributors, standards developers, and national lab researchers–not to mention experts in such fields as physiology and plant science. The prevailing spirit was that of a collaborative “meeting of the minds.” Everyone in attendance focused on sharing information, ideas, data, and perspectives on what kind of research is needed to unlock next-generation performance and energy savings, bridge the gap between the technology’s promise and today’s reality, and identify what challenges must be overcome in order to translate R&D into application. The result was a robust and exciting exchange of ideas that generated a great deal of food for thought.

WELCOME

David Nemtzow, director of the DOE Building Technologies Office (BTO) within the Office of Energy Efficiency and Renewable Energy (EERE), and Brian Liebel, IES director of standards and research, welcomed everyone. Noting that energy use in buildings comprises 40% of the country’s total energy use, Nemtzow pointed out that by 2035, LED lighting is expected to comprise 84% of all lighting installations, enabling 62 quads of cumulative energy savings and an additional 16 quads if DOE targets for efficiency, controls, and connected lighting are met – with the total cumulative energy savings of 78 quads equivalent to $890 billion in avoided energy costs. Nemtzow reviewed some of the DOE program’s new directions, including research to better understand emerging applications and lighting-application efficiency (LAE), technology integration collaborations, and field validation studies in new environments. He also congratulated Koerner Design, winner of the DOE Sustainable Manufacturing of Luminaires Challenge, and the winners of the 2020 DOE SSL student poster competition: Syed Ahmed Al Muyeed of Lehigh University and A.P. Sachintha G. De Vas Gunawardena of Rensselaer Polytechnic Institute.

KEYNOTE

In the keynote talk, Steve Burrows of Cameron MacAllister Group observed that construction is a huge market, representing 13% of global GDP, employing 7% of the global workforce, and accounting for 40% of global energy consumption and half of global resource use. He noted that 30% of global greenhouse gas emissions are attributable to buildings, 200,000 new people come to the world’s urban areas each day and need affordable and healthy housing, and 65% of the next decade’s growth in construction will happen in emerging countries, with housing becoming a huge problem worldwide and remaining out of reach financially for the poorest 20% of the population. Burrows predicted that automation gains will disrupt construction and help make it more accessible and affordable. Noting our increasing understanding of light’s physiological and psychological impacts, he said lighting will play a much broader role in the buildings of the future.

SETTING THE STAGE

DOE advisor Morgan Pattison of SSLS Inc. kicked off a panel discussion that set the stage for the rest of the workshop by providing an overview of the workshop objectives and current DOE lighting R&D priorities.

Andrea Wilkerson of Pacific Northwest National Laboratory (PNNL) offered an overview of the advanced lighting research conducted by PNNL. This research focuses on five main areas: SSL technology and system efficiency, connected lighting, grid interaction, light and physiology, and LAE. PNNL’s work involves simulation, modeling, and computation informed by studies and measurements in the laboratory and in realistic settings. Wilkerson noted that this is an iterative rather than a linear process, incorporating learning and new information and data at each step. She gave examples of the kinds of questions PNNL is researching, such as what the relationship is between circadian lighting and energy consumption, what the potential is for optimizing daylight and electric light, and whether connected lighting can provide grid services and, if so, which ones and what would their effect be on building occupants.

Brian Liebel provided an overview of IES directions in research and standards development. He explained that the IES seeks to improve the lighted environment by bringing together those with lighting knowledge and translating it into actions that benefit the public. Noting that the International Lighting Standards were adopted nearly a century ago, he highlighted two major turning points in lighting, both of which were reached in the early 2000s: the technology gains in LED lighting, and the discovery of the intrinsically photosensitive retinal ganglion cells (ipRGCs) that play a crucial role in regulating human circadian rhythm. Liebel observed that today’s SSL technologies offer virtually unlimited light-control potential, including instant-on, full-range dimming, spectral tuning, information processing and feedback, wireless communication, and use of adaptive controls – as well as amazing energy efficiency and the ability to be more precise and flexible than other lighting technologies. However, “If we are to realize the energy-savings potential of SSL, we have to know how to use it,” he said, emphasizing the four key areas of visual functions, human health, nighttime lighting, and food production.

DOE Lighting R&D Program Manager Brian Walker noted that DOE’s targets push technology to performance levels that might not otherwise be achieved, and that analysis of emerging products prompts improvements and informs DOE’s R&D priorities. Referring to DOE’s Lighting R&D Opportunities (RDO), he noted that the lighting opportunities from the 2019 RDO fall into two main categories: LAE (source, optical delivery, spectral, and intensity effectiveness) and supporting science and technology (computational modeling, building integration, electronics, advanced manufacturing technologies, connected lighting, reliability, and lighting science). Walker then discussed the lighting-technology pipeline, new frontiers in lighting, and a summary of inputs received by DOE in response to a Lighting Request for Information (RFI). He wrapped up by noting that inputs from the RFI, this workshop, and ongoing stakeholder engagement will inform DOE planning and funding opportunities moving forward.

LIGHTING APPLICATION EFFICIENCY

Morgan Pattison moderated a panel discussion that looked at the tradeoffs between source efficiency and color quality, optical control, and intensity control resulting from LAE, and that also examined how predictive computational modeling of LAE might be used as a tool to guide lighting-product design, lighting layouts, and architectural design. He began by describing the shift in emphasis from improving light-source efficiency to improving lighting-system energy savings, but noted that improving light-source efficiency is still highly beneficial and enables new opportunities in lighting application. Pattison outlined LAE framework objectives, including understanding and quantifying lighting-system energy efficiency; understanding ideal lighting for different functions of light; and being able to lay out, optimize, and predict lighting-system energy in specific settings for specific functions. He explained that improvements to source efficiency enable improved precision and new applications; that optical delivery efficiency is specific to space and function of the light; that spectral efficiency is defined by function of light, and is influenced by space and changes with time; that there’s a need to get intensity just right for function; and that all of these factors are interdependent.

Michael Herf of f.lux discussed visual considerations and nonvisual physiological responses that would inform what’s considered to be optimal lighting conditions. Focusing on light spectrum, position, distribution, intensity, optical delivery, and timing, he described the tradeoffs between light spectrum and intensity that can be engaged to achieve desired physiological responses. Herf noted that circadian responses are maximized at two times of day: in the morning and in the evening. He explained that entrainment is not stable under a single bright light pulse, and that studies have shown that a two-pulse “skeleton photoperiod” (a pulse of light in the morning and a second pulse in the evening) is the shortest duration of light known to stably entrain animals. Among Herf’s recommendations were to raise background levels of light so that we have more light in our spaces, and to adjust the spectrum based on application.

Wouter Soer of Lumileds examined LED light-source performance tradeoffs between efficacy and luminance and between efficacy and color quality. He noted that the breadth of SSL applications requires a wide range of LED capabilities, with a differentiation in luminance, spectrum, radiation profile, and package size. Soer explained that high-luminance sources are a key element of directional lighting and said the next step in optical delivery efficiency is dynamic directional lighting. He envisioned being able to light any surface from any angle with any intensity and any spectrum, as well as developing algorithms to create an infinite number of lighting distributions depending on application needs, with no wasted energy. Soer said digitally controlled pixelated LED sources can help realize this vision, but it will require collaborative effort in LED device development, electronics integration, optics, control development, and lighting design.

Sarah Safranek of PNNL discussed the use of new lighting-design software that includes the optical properties and spectral effects of the light source and space to predict delivered light intensity and spectrum at places and orientations in the space. She explained that previous light-modeling software could not account for the spectrum of the light source nor the spectral effects of the space. Safranek pointed out that the new type of modeling software can be important for co-optimizing the configuration and finishes of the space and the optical distribution, intensity, and spectrum of the light source. She cautioned that the underlying science as well as the software are still developing, and that it’s important to know the limitations of simulation tools. Safranek also noted that many surfaces attenuate short wavelengths, that optimizing LAE requires new tools, and that improved software tools allow for decisions that are more data driven.

OPPORTUNITIES FOR COLLABORATION

A panel previewed the R&D opportunities for collaboration with DOE and IES and considered what other models and methods for collaboration should be considered to support advances and translate R&D into practice. IES Manager of Government Affairs and Public Policy Alex Baker reviewed IES goals of refining knowledge about lighting and visual processes, understanding the impact of light exposure on human health, fostering the integration of lighting into the holistic built environment, and demonstrating the value of quality lighting. He noted that the fifth IES Biannual Research Symposium will take place April 27 to 29 in Orlando, Florida, and described the IES small-grant program for standards-specific research, as well as the three projects it has funded to date. Baker announced a new IES collaboration with the National Park Service, in conjunction with a memorandum of understanding with the International Dark Skies Association, to develop a new set of environmentally responsible outdoor lighting standards.

Roy Harvey of the Next Generation Lighting Industry Alliance (NGLIA) talked about NGLIA activities and opportunities to collaborate, noting that this alliance of for-profit U.S. companies works together to accelerate U.S. SSL development and commercialization through government-industry partnership.

Michele Ricks of the OLED Coalition explained that the OLED Coalition is a group of U.S. companies and advocates of OLED technology that have joined together to be the recognized voice for the OLED general lighting industry in the U.S.; to promote the industry to the government, public, and lighting community; to provide consolidated industry inputs on standards, as appropriate; and to collaborate with suppliers, academics, designers, and applications to foster new technologies.

Joel Chaddock of the National Energy Technology Laboratory wrapped up the session with an overview of opportunities to collaborate with DOE, including competitively funded R&D, core laboratory research, Small Business Innovation Research (SBIR), field validation research, and the collaborative OLED R&D testing opportunity.

LEDS FOR PHOTONS, PHYSIOLOGY, AND FOOD

Morgan Pattison moderated a panel exploring what new scientific understanding is needed – in plant, animal, and human physiological responses to light – to guide the development and application of fully optimized lighting solutions, and to connect and relate physiological responses to light across all life forms by exploring molecular responses to light and comparing responses among species. Pattison cited the limitations of existing lighting research, which has been hampered by the limited capabilities of available technologies. He noted that LED lighting technology enables better research and much greater levels of control of practical lighting solutions, but emphasized that for every lighting use, LED lighting’s technical possibilities still surpass our present understanding of how best to use the light for the application, so we need collaborative efforts to advance lighting science.

Jeff Tsao of Sandia National Laboratories provided an overarching context. He explained that the heart of SSL is a transducer or fixture that converts electrons into photons, with energy entering as some distribution of electrons and voltage over time, and light exiting as some distribution of areal space, in photon-origination angular space, in time, and in spectrum. Tsao noted that whereas we used to care only about maximizing the lm/W, we’re now starting to realize the importance of how the light is distributed in space, angle, time, and spectrum, and also about the energy productivity of light, which is symbolized by “Y” and is often used by economists to convey productivity. He explained that Y isn’t lumens but rather is a complex function of how the photons are distributed in space, angle, time, and spectrum – so that if we knew Y, we would know how to distribute those photons accordingly.

Bruce Bugbee of Utah State University discussed what Y means for plants, while George Brainard of Thomas Jefferson University discussed what Y means for human physiology. A common theme that emerged was that the effects of the distribution of light over space, time, and spectrum on plant and human physiology are far more complex than those effects are on the human visual system. For plants, blue light inhibits cell expansion, green is for humans to diagnose and enjoy plants, red is for photosynthesis, and far-red enhances cell expansion. For humans, the temporal sequence of light/dark is critical to circadian rhythm entrainment and can be extremely complex; plus, there’s an interaction between the hypothalamic and visual tracts that is yet to be understood.

THE BUSINESS OF LIGHTING

Mark Lien of the IES moderated a panel that explored the lighting-market channel from a variety of perspectives. Rather than have the panelists give presentations, he asked each of them a series of questions designed to elucidate what value their particular function brings to the project and explain what motivates them and how a better understanding of their roles can help avoid conflicts with the other skill sets involved. Diane Borys of Noctiluca Lighting Design and H+W Engineering represented the lighting-designer perspective. Megan Carroll of New York Digital provided a manufacturer’s-rep perspective. Erik Ennen of the National Association of Lighting Management Companies (NALMCO) represented energy service companies (ESCOs). Bob Preston of Capital Electric/Sonepar provided an electrical distributor’s perspective.

LIGHTING MARKET TRENDS

Clay Elliott of Guidehouse gave an overview of major trends and changes in LED lighting adoption and their impact on energy use, examining which applications are taking off and which technology limitations might be holding others back. His talk was based on analysis conducted for three recently or soon-to-be-published DOE market reports: the SSL Forecast Report, the LED Adoption Report, and the Energy-Savings Potential of Agricultural Lighting Report. Penetration of LED A-lamps has reached 32.9%, but penetration of connected lighting controls remains small, at just 0.2%, even though LED linear fixtures and high/low-bay luminaires offer the most energy-saving potential when paired with controls. By 2035, LED lighting is expected to comprise 84% of all lighting installations, enabling 62 quads of cumulative energy savings between 2017 and 2035. LED lighting in general illumination is reaching the majority phases of product adoption, with most of the applications clustered in the “early majority” and “late majority” phases, though there’s still room for growth. In 2019, an estimated 89 million square feet of plant grow area was illuminated by horticultural lighting, which was 6% LED and was estimated to consume 9.6 TWh of electricity for lighting annually. In 2019, an estimated 5 billion square feet were illuminated by animal lighting (for poultry broiler, poultry layer, hog, and dairy production), which was 46% LED and was estimated to consume 3.7 TWh annually. As LED lighting continues to approach the majority of installations, connected lighting and LAE will be key to unlocking the next generation of energy savings.

NEW CONSIDERATIONS FOR SSL SYSTEM RELIABILITY

Monica Hansen of LED Lighting Advisors moderated a panel discussion exploring different aspects of the reliability of SSL systems, including color-tunable LED lighting, dim-to-warm lamps, and OLED lighting. Hansen described the challenges of characterizing dim-to-warm lamps. The LED Systems Reliability Consortium (LSRC) studied the performance characteristics of dim-to-warm lamps by measuring them at different dimming levels to develop a best-practices protocol. Testing only at maximum power does not provide full performance information, since efficacy, flicker, and temporal light artifacts all change at different dimming levels. These parameters can fall out of range of some performance standards or specifications upon dimming, so at least three levels should be measured to ensure that all LED primaries are encompassed.

Lynn Davis of RTI International discussed the accelerated stress testing of commercially available OLED lighting, which found that the luminous flux maintenance of OLED panels and luminaires has improved significantly. Rated luminous-flux maintenance lifetimes > 36,000 hours are now possible for room-temperature operation for neutral-white OLED panels, though improvements are still needed in luminous efficacy. Davis finished up his talk by considering the reliability challenges of multichannel drivers, highlighting the impact of surge suppression in EMI filtering on driver reliability. Degradation of these circuits will impact driver operation, so monitoring their performance may provide health-status indicators. 

Bob Davis of PNNL discussed the interim results of a long-term study measuring the performance of LED downlights. After more than three years of testing, approximately 30% of the products have failed either catastrophically or parametrically. Chromaticity shift was the dominant initial failure mechanism and was frequently accompanied by lumen depreciation.  Many products failed before their rated lifetime or warranty period was up. This may be in line with the distribution of failures as understood by the manufacturer but is probably not expected by users. Testing on the remaining products will continue until 50% of the population fails.

Ben Sweet-Block of Signify discussed the challenges of designing multichannel systems, which are more complex (more data, more components, more drivers, more interdependence with installation conditions, etc.), and generate more opportunities for failure, than single-channel systems. Factors of reliability to consider include the natural environment (thermal exposure, surge events), installation conditions (power quality, signal noise), and system interactions (network reliability, third-party controls, user behavior and error). Time is the biggest factor affecting reliability; the longer the use, the more the exposure. Connected lighting systems, especially multichannel lighting, lead toward longer warranty periods. There is a higher barrier for early adoption in professional lighting than in consumer lighting, due to the higher investment, so design for warranty strategies, such as monitoring and/or upgradability, are required.

POSTER SESSION

The evening of Day 1, researchers representing 60 projects presented their work in a poster session that provided attendees with additional opportunities for one-on-one discussion, information exchange, and potential partnering. Two posters representing the SSL student competition included winners from Lehigh University and Rensselaer Polytechnic Institute.

OPEN DISCUSSION FORUMS

Day 2 concluded with three concurrent informal sessions that involved open discussion and Q&A on emerging areas of lighting science:

• New Frontiers in Lighting explored SSL-synergistic technologies with significant potential for energy savings, including displays, agricultural lighting, germicidal irradiation, Li-Fi, high-power photonics, and power electronics. Among the questions considered were what the energy-savings opportunities are, what the key technology challenges associated with improving energy efficiencies are, and how overcoming these challenges might benefit from synergies with SSL.
• Translating Physiological Research into Practice examined the challenges in designing, installing, and evaluating lighting systems for health and well-being. The overall objective was to identify the best practices to employ today, and the future research needs to ensure that lighting is optimized for both energy efficiency and human response.
• Clarifying the Value Proposition for Connected Lighting Systems considered the promise of connected lighting to make lighting control seamless and provide a variety of other new benefits and features. So far, market success has been elusive and system configuration, operation, and maintenance remain frustratingly complicated, with new value propositions hard to quantify and justify.

MATERIALS RESEARCH & PRODUCT INNOVATION TRACK SESSIONS

Track sessions enabled attendees to take a deeper dive into technical discussions on a wide range of topics. Expert speakers kicked off technical discussions that examined current research efforts and future research needs, with an eye toward informing DOE SSL program planning.

Advances in LED Devices and Materials

Jeff Tsao moderated a panel discussion of some of the latest innovations and new directions in light-emitting and wavelength-converting materials and devices.

Jim Speck of the University of California at Santa Barbara discussed three topics related to green LED efficiency: polarization barriers to hole injection, field screening for reducing polarization fields, and the use of V defects for volumetric injection of holes. The latter was a major breakthrough out of Nanchang University in China; volumetric carrier injection is a completely new paradigm in InGaN light-emitting device architecture, with a lot of headroom. It’s the first paradigm that addresses the core issue of hole injection while circumventing the c-plane voltage drop. While many challenges remain, both on the technology side (either increasing packing density of the volumetric injectors or enhancing hole diffusion in between injectors) and on the science side (understanding the formation of volumetric injectors so they can be engineered), continued research is worth pursuing.

John Epler of Lumileds discussed advances in direct (AlInGaP) and phosphor-converted amber/red LEDs. The improvements in this space are incremental, whereas more of a “home run” would be an InGaN red LED, on which V-defect work could make a big impact.

Jonathan Owen of Columbia University discussed quantum dots (QDs) for wavelength down-conversion. He looked at the new architecture that in recent years has enabled much-higher performance: a QD in which there is a core, then a quantum-well shell that is light-emitting, followed by a much thicker shell that is light-absorbing. This architecture enables improved accommodation of strain and reduces parasitic Auger recombination.

Harald Koenig of Osram discussed the status of high-efficiency blue lasers. Much progress has been made, and in 2019 2.2W blue lasers were demonstrated at 46% wall-plug efficiency. There are many challenges to achieving higher efficiency – particularly reducing the optical loss that laser diodes are more susceptible to than are LEDs because of the much longer optical path length. Because laser diodes are cavity devices, the optical path length before a photon escapes can be a few mm, compared to only tens of microns for LEDs.

Advances in OLED Devices and Materials

Lisa Pattison of SSLS Inc. moderated a panel discussion that reviewed recent advancements in long-lived blue materials and explored novel device structures and materials that aim to improve charge balance or light outcoupling, extending OLED device lifetime.

Jian Li of Arizona State University presented an overview of emitter approaches, describing the shortcomings of phosphorescent and fluorescent mechanisms and how thermally activated delayed fluorescence (TADF) and metal assisted delayed fluorescence (MADF) are being explored to achieve stability and efficiency simultaneously. This is a particular concern for blue emitters, for which the tradeoff (between stability and efficiency) has presented an ongoing challenge. Li shared recent results of blue-emitting Pt and Pd complexes that suggest that long lifetimes and high efficiency are attainable and emphasized the key role that new emitter designs can play in blue OLED development.

Chris Giebink of Penn State University focused on improving OLED performance via semiconductor dilution. He suggested modifying what are often considered “intrinsic” properties of OLED materials – such as refractive index and glass transition temperature – without re-engineering the OLED molecules. Giebink explained that only a small percentage of molecules participate in transport, so dilution of the organic semiconductor can actually improve transport by reducing charge trapping. With the appropriate dilution material, the index of refraction can be lowered to better match that of the OLED substrate for better light extraction, and thermal stability can be improved.

Michele Ricks of EMD Performance Materials gave a review of transport-material design for charge-balanced, efficient OLED devices. She emphasized the key roles of the blue stack and charge-generation layers in efficient white OLED devices. EMD’s approach focuses on understanding the full stack, since the interplay between the combined hole and electron transport and blocking layers determines overall performance. Thus, a portfolio approach is recommended, which necessitates extensive combination screening.

Jason Hartlove of Nanosys talked about quantum dots (QDs) for SSL, focusing on quantum dot electroluminescent (QDEL), which he called the future emitter material for low-cost, ultra-thin, flexible emissive displays. Hartlove described Nanosys’ role in the display industry and outlined the company’s roadmap toward QD electroluminescence SSL. The potential advantages of QDs include high power efficiency, engineerable spectrum for color management and high efficiency, super brightness at low voltage, low-cost solution process, and easy color patterning. QDs are also compatible with established OLED lighting aspects, including substrates, light extraction, encapsulation, and drivers. The key obstacle is to improve lifetime for commercial applications.

LED/OLED Device-Level Light Extraction and Control

Morgan Pattison moderated a panel discussion that explored state-of-the-art light extraction and control for both LED and OLED devices, and covered possible paths forward, along with some fundamentals that included cavity effects, the Purcell effect, and plasmonic effects.

Claude Weisbuch of the University of California at Santa Barbara described the evolution of light-extraction techniques for inorganic LEDs, the state of the art, and plasmonic and Purcell effects that can affect efficiency and light extraction. He also touched on the status of OLED light extraction. Weisbuch noted that nitride and other inorganic semiconductors reach ultimate light-extraction efficiency performance through light randomization techniques, either disorder or shaped substrates or both. He explained that losses are minimized because light travels about three roundtrips before escaping, and that losses can diminish with improved designs and materials. Weisbuch stated that other techniques based on mode manipulation (instead of mode destruction) are less effective, as either light travels too much in the LED (microcavities and photonic crystals) or interacts too much with metals and their losses (surface plasmons). However, these techniques can provide better directionality or polarization conservation (in the case of polarized emission, as for m-plane-grown LEDs).

Andrew Kim of Glint Photonics offered further discussion on inorganic LED light-extraction approaches, as well as package and lighting-level light-extraction techniques that can extract more light and enable optical directional control for LED-based lighting concepts. He noted that light extraction at the die and package levels has made incredible strides, especially for GaN, and that there are LED performance metrics beyond raw efficacy that impact system-level performance, especially in directional lighting. Kim explained that anti-reflective surfaces have clear benefits at the luminaire level for extraction and glare but need further study to see where they are practical in cost, process, compatibility, and reliability. Citing the slow progress of downlight efficacy and the fact that the DesignLights Consortium^® is raising its threshold for Interior Directional – Standard from 65 lm/W to 80 lm/W, he emphasized that more-efficient means of light control are important.

Michael Boroson of OLEDWorks described the status and challenges for OLED light extraction and the use of internal high-index scattering layers to improve light-extraction efficiency. He said there are two keys to improving OLED lighting efficacy: increasing light extraction from 50–55% to 70%, and replacing fluorescent blue with stable phosphorescent, thermally activated delayed fluorescence (TADF), or hyperfluorescent blue. Boroson noted that waveguide mode is the main source of lost photons in commercial OLED lighting panels, and that current scattering-type light extraction meets most light-extraction requirements but does not extract all waveguided photons. He said an advanced light-extraction technology is needed to reach 70%, adding that efficacies of up to 160 lm/W are possible if the DOE targets for light-extraction and blue internal quantum efficiency are achieved. Boroson said that at 160 lm/W, OLEDs can meet mainstream lighting-market requirements for high-lumen applications, but DOE support is critical to achieving these goals and to keeping the U.S. as the worldwide leader in OLED lighting.

Jongchan Kim of the University of Michigan described the use of a sub-electrode micro-lens array to improve light-extraction efficiency in OLED devices. This optical array can increase the portion of light that is extracted from the OLED layers to the substrate, and then the light can be extracted from the substrate. Kim explained that the concept is enabled by using a high-index planarizing waveguide on top of a diffuse reflector, eliminating the surface plasmon polaritons, waveguide, and substrate modes. He said he and his colleagues have achieved 250% increased external quantum efficiency compared to an identical device that was deposited on a metal-reflector substrate.

Directions in Optical Control

Jeff Tsao moderated a panel discussion on new approaches to light whose intensity distributions can be engineered in space and time – including novel sources for producing such light, and potential applications for using it.

Wendy Davis of the University of Sydney in Australia talked about the combined tailoring of spectral and spatial light distributions. Her take-home message was that spectral optimization plus spatial control equals more than the sum of its parts. The basic idea is that when you are lighting a colored object, full-spectrum light is not necessary, whether to make the object look realistic or to make it look its best. By narrowing the spectrum, the object can still look realistic or nice, but energy can be saved by confining the light to the portion of the spectrum where the light is created most efficiently. Davis said that energy savings of 10% to 40% are possible, depending on the type of object and how colored it is.

Billy Tubb of the IES discussed how theatrical luminaires might inform general illumination in the future. He looked at how the real-time control of spatial and spectral distributions in the theatrical and performance lighting industry has improved general illumination in the past and present, and considered how it can do so in the future. One important point, Tubb noted, is that single projectors are not enough, even if highly pixelated; you need multiple projectors, because the angle of incidence of the incoming light onto surfaces of the room is also important.

Sergey Vasylyev of Lucent Optics discussed the design of wide-area LED luminaires with ultra-thin and flexible form factors. Ultimately, these types of luminaires will be able to do much of what OLED light panels can do. One important area of focus for the future, Vasylyev said, is to make such luminaires thinner, which will require smaller LED sources or even laser diode (LD) sources.

Oleg Shchekin of Lumileds discussed micro-LED-based projection illumination for headlights and general illumination. The systems he discussed are LED-based and appear to be taking market share from LD-based systems; they’re already available in automobiles in Canada and Europe, although not yet in the U.S.

Lighting Product Innovation

Monica Hansen moderated a panel discussion that explored how technology advances are impacting luminaire and system designs, as well as the challenges that remain in the path of continued development.

Mark Hand of Acuity Brands discussed lighting designs for visual comfort and reviewed the evolution of LED outdoor lighting. Initially, LED area lights focused on uniform lighting layouts and efficiency but had a lot of glare. Recently, designs have evolved to prioritize visual comfort in addition to illumination patterns and efficiency. New waveguide designs with recessed sources and visual transition zones have led to area lighting with low glare.

Dan Schwade of Acuity Brands continued the discussion of visual comfort with a presentation on new OLED lighting designs that are both comfortable and approachable. He updated the current performance of OLEDs that allow for sleek and minimalistic modular and configurable design choices. The luminaire is a conversation piece and is meant to be seen and draw attention to a space. Forward-looking trends include combination LED/OLED light fixtures, curved OLEDs, and segmented OLEDs for wayfinding and signaling.

Heinz Willebrand of Signify shifted gears to the functionality of LED lighting and the use of LiFi for communication. With the continuing growth of IoT devices, the volume of data being transmitted is massive, leading to a more-clogged spectrum for communication. LiFi provides the opportunity for additional bandwidth in the visible spectrum and, what’s more, is secure and reliable and can offload traffic from WiFi in high-traffic areas. Use cases include applications – such as industrial settings – where the penetration of radio frequency waves is difficult, as well as offices requiring secure spaces or bandwidth in high-traffic areas.

Paul Pickard of Ecosense Lighting discussed the need for a lighting intra-fixture standard to allow open integration between drivers and other elements within fixtures, which are currently proprietary for different lighting companies. The D4i DALI intra-fixture standard is a good start but really is just digitizing what is happening today, while not really moving to true interoperability. Pickard said that a community-based cooperative digital bus architecture is a way forward and described how this is analogous to the CAN Bus communication that changed how devices are connected in automotive applications. Key characteristics of a community-based cooperative digital bus architecture include low latency, scalability, flexibility, and reliability.

LED Integration and Manufacturing Challenges

Morgan Pattison moderated a panel discussion of advanced manufacturing technologies that could be used with lighting to improve manufacturing efficiency, reduce part count, enable product customization, and enable on-demand manufacturing.

Michael Bremser of Tempo Lighting talked about how his company is using additive-manufacturing 3D printing to reduce part count and simplify inventory and manufacturing for existing lighting products. He described how, with 3D printing, the total system cost should be considered, rather than just a part cost, since many of the benefits of 3D printing are not well described just by part cost. 3D printing can enable quick pilot production for initial testing and customer validation, and can also enable low-volume, high-mix configurations and custom parts for specific products, as well as production of parts to be used as aids in the manufacturing process. 

John Trublowski of Eaton discussed the status of additive-manufacturing approaches for full production of outdoor, roadway type luminaires. He explained how 3D printing can be used to print parts on-demand with fewer components and subassemblies and with integrated mechanical features and electronics. Printed luminaires can have a greatly reduced manufacturing footprint, a consolidated supply chain, reduced inventory, and improved manufacturing responsiveness.  Eaton is working on printing of the housing and mechanical structure with suitable thermal management, optics, and printable electronics for the driver.

Designer and engineer Chikara Inamura gave a presentation on 3D printing of glass. He described the development of tools to print glass at the MIT Media Lab, and discussed how the processes could eventually be used to provide optical components for lighting products. Inamura showed some early printed parts that were developed, to illustrate the potential of the specific 3D glass manufacturing process, which is still at an early stage. 

Eugene Chow of Palo Alto Research Corp. described a new self-assembly technique that can deploy small optical components, including LEDs, into a matrix. Different components can be guided into specific sites on a holding wafer and then transferred to a final submount. Chow showed videos of the process and described how it can be used for a range of components, including micro integrated circuits and micro-LEDs, and could be used for a range of applications, such as displays and lighting.

OLED Integration and Manufacturing Challenges

Norman Bardsley of Bardsley Consulting moderated a panel discussion about the significant challenges that lie in the manufacturing of OLED panels and the integration of those panels into lighting systems in a manner that preserves the attractive form factor of OLEDs and allows full control of multiple panels.

Jeff Spindler of OLEDWorks gave a comprehensive overview of the manufacturing and integration of OLED panels. He confirmed that deposition of the organic materials is the key process in substrate processing. The thickness of the 40 organic layers must be controlled tightly, typically to +1%, to ensure that the color point remains within two steps on the International Commission on Illumination (CIE) scale (u',v'). Particle defects and electrical leakage or shorts are the main obstacles to increasing the size of the OLED panels. Improved deposition techniques are needed to increase the material utilization of expensive organic materials and reduce the processing time. Singulation and integration of the separated panels into luminaires represent a significant portion of the processing/production costs, which is particularly important for the segmented panels that are planned for automobile applications. Care needs to be taken in cutting flexible panels, to prevent the formation of cracks, which often spread inwards from rough edges.

Max Shtein of the University of Michigan presented a detailed analysis of the available techniques for deposition of organic materials, contrasting organic vapor phase deposition (OVPD) and organic vapor jet printing (OVJP) with the dominant vacuum thermal evaporation (VTE). OVPD uses an inert gas stream to carry the organics from the source evaporation chamber to the substrate. This increases material utilization and provides an additional mechanism for the control of the deposition rate. Hot walls also reduce deposition on the walls, which otherwise leads to wasted material and defect formation through subsequent flaking and detachment. Although OVJP is being developed primarily for display applications, it could be useful in lighting by enabling color tuning through horizontal separation of the colors.

Bill Reisenauer of LED Specialists focused on the development of low-power drivers for OLED panels. He began by stressing the importance of compatibility with low-voltage distribution networks that are easily reconfigurable, with minimal involvement of licensed electricians. Reisenauer described the goals of the current DOE SSL project to increase the driver efficiency to over 90%, using active clamp flyback and incorporating wide-bandgap (WBG) materials such as GaN transistors. The WBG semiconductor materials allow power electronic components to be smaller, faster, more reliable, and more efficient than their silicon (Si)-based counterparts and can operate at higher temperatures. They can eliminate up to 90% of the power losses that currently occur during AC-to-DC and DC-to-AC electricity conversion. 

LIGHTING SCIENCE TRACK SESSIONS

Track sessions enabled attendees to take a deeper dive into technical discussions on a wide range of topics. Expert speakers kicked off technical discussions that examined current research efforts and future research needs, with an eye toward informing DOE SSL program planning.

Latest Understanding on Physiological Impacts of Lighting

Monica Hansen moderated a panel discussion that reviewed the latest scientific findings related to lighting for health and well-being, examined what is generally agreed-upon and what research is necessary to fill gaps in understanding, and explored how the existing knowledge can be deployed into lighting products and design standards to provide the “best” light for occupants.

Luc Schlangen of Eindhoven University of Technology in the Netherlands talked about how light regulates our sleep and physiology and is bringing about new lighting metrics, insights, and designs. He discussed how our photo-history plays a role in our physiological response to light: Prior light regulates sensitivity to subsequent light. Early-morning light administration will shift the circadian clock earlier, enabling an earlier bedtime. Also, early-evening light reduces our acute physiological responses to late-evening light exposures. Schlangen reviewed the new CIE set of common metrics that should be used to quantify the nonvisual effects of light. These five a-opic values quantify the different action spectra associated with the five retinal photoreceptors. Schlangen cited the need to adopt metrics for dose-response research and lighting specifications, as well as for more high-quality, well-controlled real-life studies. The initial guidance for healthy lighting is high-melanopic equivalent daylight illuminance (EDI) in the day and low-melanopic EDI at night.

Timothy Brown of the University of Manchester in the United Kingdom discussed quantifying and predicting nonvisual responses to light. He observed that melanopic illuminance provides a reliable approximation of the spectral sensitivity of melatonin suppression across a wide range of conditions, but that it’s not clear whether this is also true for circadian responses, which don’t always correlate with melatonin suppression. Brown showed data that indicated that the melanopic illuminance provides the best available predictor of circadian phase-resetting responses, but the spectral sensitivity of daytime alerting responses to light is unclear. Brown stated that melanopic EDI provides a robust and widely applicable metric for predicting the nonvisual impact of light exposure, and that there’s strong support for using this as a guiding principle in future lighting design. He noted that there are multiple ways of adjusting melanopic illuminance, other than simply adjusting short-wavelength content. Approaches for adjusting melanopic illuminance independently of color may be more beneficial.

Jamie Zeitzer of Stanford University focused on lighting to improve human health and behavior. Citing experimental evidence, he explained that in many instances, just providing light is insufficient to engender the health or behavior changes we expect. Occupant behavior is critical to take advantage of lighting designed for health. Zeitzer also focused on the challenge of moving research from the lab to the real world. Studies moving out of the lab need to have endpoints that are important to the consumer, have large enough sample sizes to detect small effects, and ideally be conducted in settings in which data can be collected passively and have functional relevance in a business-to-business framework. In these studies, we need to measure the endpoint of interest, since not all non-image-forming aspects of light follow the same physiology. Also, small effect sizes can be potent at scale but need to be studied appropriately. Leveraging big data is also a needed bridge for understanding the real-world implications – some of the data already exist and should be analyzed.

Great Promise, Few Options: Can Advances in Color Science Shift the Market?

Michael Royer of PNNL, Lorne Whitehead of the University of British Columbia, and Tony Esposito of Lighting Research Solutions discussed the range of tools available for characterizing a light source’s spectral power distribution (SPD), including tools from the past (e.g., CRI), the present (e.g.,TM-30), and the future (e.g., Rt, CCT10). The discussion covered ongoing color-science issues, with the central idea being that improving color quality, even at the expense of luminous efficacy, can improve the overall value of lighting, or “joy per joule.”

To begin, Whitehead made the case that trading off a small number of lumens for improved color quality is an appropriate path to improving well-being, and he also covered the fundamentals of color appearance. Royer discussed SPDs and all the quantities derived from them that are affected by spectral engineering. He explained that to date, a simplification has been used in spectral engineering where, given a CCT and minimum color fidelity (e.g., CRI), the lm/W are maximized. This results in SPDs that sacrifice appropriate color rendition for the sake of small improvements in luminous efficacy, with LED technology largely delivering performance similar to that of fluorescent lamps. Esposito presented TM-30, TM-30 Annex E, and Rt as new tools for breaking from the status quo. A final lightning round covered important ongoing research topics, including observer variability, color discrimination, color-rendition variability, far-red, light-level variation, tuning for the visually impaired, and updating chromaticity.

Searching for Holy Grails

Brian Liebel of the IES moderated three separate discussions focused on three aspects of SSL that are of special interest for their high-value potential. In the first discussion, Brad Schlesselman of Musco Lighting and Sam Berman of Berman Consultants considered the question of whether we should modify how we evaluate light-source efficacy. The traditional measurement for illumination, which is based on the two-degree photopic luminous-efficiency function, has been questioned as an accurate indicator of visual response for many years. Work supported by DOE over the last 30 years determined that, under the normal condition of a full field of view, relatively higher amounts of blue-light content improved visual acuity and increased brightness perception, which would have an effect on visual efficiency and thereby impact energy efficiency. More-recent work has tied this effect directly to the ipRGC photoreceptors. Schlesselman and Berman brought the latest relevant research to the forefront.

Bob Davis explored the most-recent work being done on quantifying glare, in an attempt to define metrics that go beyond just knowing glare when we see it. SSL has been accused of being too harsh or causing too much glare, but a definition of glare has eluded us for far too long and is necessary in order to understand how to design better luminaires and optical systems.

Michael Herf discussed the value proposition of creating an SPD databank where light-source SPDs can be collected and referred to by researchers and laboratories seeking to better understand the correlations between spectral composition and research results. SSL systems have the unique ability to finesse and refine SPDs, which affect visual and nonvisual responses to light, and these refinements cannot be captured in the simplistic metrics of CCT and CRI (or Rf). Understanding the effect of light on visual or physiological outcomes requires a detailed description of the light’s SPD, and this is becoming more important in the realms of light and health as well as horticultural lighting.

Considerations for Non-Human Physiological Responses to Light

Morgan Pattison moderated a panel discussion covering lighting considerations, recent research, and the latest best practices for horticultural lighting; lighting for animal production; and minimizing lighting’s impact on wildlife and the environment.

Kale Harbick of the U.S. Department of Agriculture’s Agricultural Research Service considered the importance of light uniformity for plant growth. Non-uniformity in light levels can result in uneven growth and loss of yield and can also confound plant growth studies, due to the variations in light intensity. Harbick described software he developed to find lighting layouts that provide optimal light uniformity based on the optical distribution properties of the luminaires. The software “found” unexpected layouts with improved uniformity that were set up in a research greenhouse, and the results were validated. The software could also define layouts with optimal heights for the individual luminaires. 

Bruce Bugbee described the ultimate practical limits of plant growth based on understanding of the photons-photosynthesis process that converts light to plant biomass. The analysis showed how the relationship between provided photons and biomass can be calculated and then, with an understanding of the efficacy of horticultural light sources, the biomass per lighting energy can be calculated to understand the fundamental economic constraints of growing plants under electric lighting. This analysis can be used to determine the conditions and types of crops that are economically feasible to grow under sole-source electric lighting.

Jeremy White of the National Park Service described the impacts of outdoor lighting on wild animals. His talk included a description of natural lighting conditions at night and light levels from anthropogenic light sources. The range of species affected by anthropogenic light was defined, and differences in visual function were described for various species. Specific studies that showed changes in functional behavior for nocturnal animals based on lighting were described. Non-natural sources of light have altered the natural day-night cycle spatially, temporally, spectrally, and in overall intensity. This has affected wildlife across all taxa at every stage in natural history. Spectra of lighting are important, but so are intensity, timing, duration, polarization, and flicker. 

Curtis Leyk of Signify discussed the various uses of lighting in animal production. He described the visual system of chickens, hogs, and fish that are reared indoors, as well as the benefits of advanced lighting for these animal-production applications. Chickens are tetrachromatic and have extended sensitivity to light in the UV range of the visible spectrum, as well as an extraretinal neural pathway through their skull. Red light has been shown to increase growth rate at the beginning of the rearing period, increase movement later in the rearing period, and stimulate hormones essential for sexual maturation. It also stimulates egg production, reduces the amount of feed necessary per egg without negatively affecting egg quality, and stimulates melatonin production. Blue and green light enhances early-age growth rate by improving proliferation of skeletal muscle cells, promotes myofiber growth due to more-effective stimulation of testosterone secretion, enhances later-stage growth by elevating plasma androgens, and has been identified as the most potent wavelength for regulating melatonin secretion. For hogs, lighting can be controlled to reduce stress, modify feeding behavior, enhance fertility, accelerate growth, improve feed conversion, increase piglet wean weight, and reduce piglet pre-wean mortality. For aquaculture, lighting can be optimized to improve fish-feed visibility and promote deeper feeding, which reduces the negative impacts of sea lice on the fish.

Exploring Effects of Product Valuation on Energy Use

Marc Ledbetter of PNNL moderated a panel discussion reviewing the results and analysis of a recent study that included a survey of potential lighting-product buyers and that aimed to assess how improving quality and expanding product functionality affect product purchase decisions and energy use. Ledbetter gave a short presentation that introduced a study of the energy-savings opportunity associated with select research, set the context, gave a general introduction to the methodology used, and reviewed the key economic assumptions made to make the approach viable.

Lisa Skumatz of Skumatz Economic Research Associates (SERA) introduced non-energy benefits methodology and reviewed its development for the electric-utility industry and its regulators. She described the steps SERA took to complete its part of the study, including the use of advanced luminaire descriptions developed by PNNL, surveys conducted on large groups of potential buyers of those advanced products, and the steps SERA took to convert the survey data into estimates of the monetary value potential buyers associate with the features incorporated into the advanced LED products.

Valerie Nubbe of Navigant reviewed the DOE SSL Lighting Market Model, describing its key features and functions, explaining how it was used in the study, and presenting estimates of the energy-savings opportunity that resulted after making adjustments for the inputs from the SERA part of the overall study. Navigant estimated that lighting-energy use would be 10% lower in 2035 relative to a baseline “current SSL path” scenario.

Translational Research in Physiological Responses to Light

Bob Davis moderated a panel discussion that looked at the latest in translational lighting research, which incorporates the findings indicated by basic research in laboratories with explorations involving human participants in complex, realistic settings. This research documents the holistic effects of light on people and demonstrates the potential magnitude of the effects when the complex mix of variables that affect realistic settings is considered. Davis discussed how translational research can apply theory-of-change principles to link lighting variables to human outcomes that are meaningful to the end use being studied. He reviewed several active PNNL projects in patient rooms, neonatal care, behavioral health, and senior care.

Ron Gibbons of Virginia Tech Transportation Institute (VTTI) explored the challenges of conducting and interpreting naturalistic lighting studies in outdoor settings. One rule of thumb, he said, is to carefully control what you can control and even more carefully measure what you can’t control. To illustrate his points, Gibbons discussed two VTTI studies: one that investigated the impact of outdoor lighting on human health, and the other that looked at adaptive lighting for streets and residential areas. He observed that naturalistic data can be a “mess,” and that careful experimental approaches must be taken to determine their meaning. Gibbons cautioned that when evaluating research and results, one should make sure the co-variants are documented and controlled, and that the statistics are valid.

Mariana Figueiro of Rensselaer Polytechnic Institute’s Lighting Research Center (LRC) considered the challenges and successes of light-and-health field studies. She discussed a number of LRC field studies involving office workers, older adults, Alzheimer’s patients, and bone-marrow-transplant cancer patients, and concluded that, although they’ve shown that knowledge from the lab can be translated into the field, blue-enriched light and tunable light are not in themselves sufficient to guarantee positive results, and that amount, duration, and timing are just as important, if not more so. The key, Figueiro emphasized, is measurement of total light exposure.

LIGHTING SYSTEMS & BUILDING INTEGRATION TRACK SESSIONS

Track sessions enabled attendees to take a deeper dive into technical discussions on a wide range of topics. Expert speakers kicked off technical discussions that examined current research efforts and future research needs, with an eye toward informing DOE SSL program planning.

Building Integration Challenges

Michael Poplawski of PNNL moderated a discussion that explored the question of where the lighting industry should continue investing its resources as it seeks to integrate effectively with other buildings systems. Poplawski asked whether new disruptive technology might drive or be required to drive more integration. He briefly discussed three technologies as a means for exploring that question. The deployment of Power over Ethernet (PoE) often brings interoperability and cybersecurity earlier into the design and development cycle and results in improved IT-OT (information technology – operational technology) integration and cybersecurity, but it has a high initial material cost and can be difficult to retrofit. Digital electricity makes the building core’s electrical infrastructure more flexible and controllable, but it, too, has a high initial material cost and can be difficult to retrofit. The use of digital twins offers a range of advantages, but there’s no common understanding of how to build one, what it costs, and what it delivers.

Joel Timmins of Markon Solutions took a different tack, exploring whether and how new project-management processes might drive or be required to drive more integration. He discussed the concept of agile construction management, in which universal agile principles are applied to lean manufacturing, construction manufacturing at risk, design-build, progressive design/build, and integrated project delivery processes using a common framework. By using agile processes to address the needs and issues that arise as the project evolves, design intent – which often includes system integration – can be more easily maintained and delivered, even while preserving the unique strengths of each delivery method.

Connected Lighting System Complexity: Identifying the Challenges and Finding Solutions

Naomi Miller and Ruth Taylor of PNNL moderated a two-part panel that looked at the challenges involved in specifying, installing, and configuring today’s connected lighting systems, drawing on perspectives from a lighting designer, manufacturer, manufacturer representative, electrical contractor, and utility program manager – as well as looking at potential solutions to those challenges.

Lighting designer Teal Brogden of Horton Lees Brogden Lighting Design, and manufacturer’s representative Megan Carroll of New York Digital, offered insights into the complexities of such systems and how they differ from previous lighting systems in many ways. For example, because no two connected lighting projects are alike, the responsibility for each stage of the controls implementation isn’t always clear. And the process for getting a control system specified is complicated: A controls narrative or sequence of operations is sometimes written by the lighting designer or electrical engineer and often gets translated by the manufacturer’s rep into a bill of material, which is bid to the electrical contractor for ordering and installation. But it’s often unclear who ensures that the specified luminaires will all work with the control system, or that the control system will deliver the anticipated performance.

Lighting consultant Dan Blitzer of the Lighting Practice Workshop provided the manufacturer’s perspective on intellectual property and branding competition, noting that because of those two factors, few controls manufacturers offer any interoperability of parts – which tends to silo choices into brand packages, reducing the ability of smaller manufacturers to provide products and limiting specifiers’ choices. And because of the LED revolution’s progress, manufacturers no longer have the luxury of extensive development time for products, which are sometimes released before they’re fully functional. With the movement of controls into the IT realm, the question arises as to whether IT companies will take over selling lighting systems, or if the luminaire manufacturers will take over the controls configuration and data collection.

Chris Wolgamott of the Northwest Energy Efficiency Alliance highlighted the aim of utilities, which is to improve controls performance in smaller, energy-focused, code-minimum projects. To please customers, utilities want to reduce the number of systems that end up being disabled, and their desire for simple systems may be why only 5% of all projects have a control system more sophisticated than a wall switch – a situation that offers a big energy-saving opportunity.

Anthony Mulcahy of E.S.B. Electric Corp. shared his perspective as an installer, noting that he constantly encounters new control systems that each have a slow learning curve. There’s also the question of who should train owners and end users to use, tweak, and maintain these systems, which are often so complex that the facility manager doesn’t bother to learn the interface but instead calls the contractor back for simple reprogramming or training of users.

Potential solutions that were suggested in part two of the panel ranged from developing an industry-standard sequence of operation for code-minimum projects, to providing for more face-to-face meetings and jobsite visits to solve installation and configuration issues, to developing common connected-lighting standards, or at least some kind of nonproprietary hardware or software to create a common platform that manufacturers can customize. But there’s still quite a ways to go before the market sees smart lighting systems that are easier to specify and install, simpler to program, and much more intuitive to use.

Lighting System Data: What Are We Learning?

Andrea Wilkerson moderated a panel discussion that looked at examples of how lighting data are delivering value, from optimizing building performance to improving occupant experience.

Vladi Shunturov of Acuity Brands noted that big-box retail – including Target, Walmart, and Best Buy – is the fastest adopter of Acuity’s Atrius technology. The Atrius technology has over four million nodes deployed, with billions of data points each month. Shunturov mentioned that the big-box retail stores are in the last phase of lighting retrofit that we’ll see for a while. Acuity’s solution leverages indoor positioning based on shopping carts, baskets, or individuals with the retailer’s app installed on their smartphone, to anonymously track the position of shoppers. This tracking provides brick-and-mortar stores with information similar to what is delivered by browser cookies during the online shopping experience. These data can be used to test different hypotheses in a store, with the retailer making a change and then tracking how it affects customers in the store, allowing the retailer to determine whether the change should be made in other stores. Shunturov highlighted the need for standards development so that individuals can focus on software solutions without worrying about underlying hardware and building-infrastructure complexities.

Alex Cooper of the Smithsonian’s National Portrait Gallery revealed that he’s making an investment in technology-forward projects, including data-driven lighting in the 10,000-square-foot America's Presidents Gallery, with the system expanding to the remaining 300,000 square feet in the building. The gallery features 160 gateways, with the building automation, lighting, and audiovisual systems to all have access to the same database that the 15,000 fixtures populate. A 15% light-exposure reduction was achieved for the sensitive artwork and objects with the new lighting system – a considerable reduction – while improving the visitor experience. Previously, three people were needed to check, fix, and re-aim the lighting, whereas now just one person can do it by running scripts and checking fixtures remotely. Cooper stressed that bidirectional communication, interoperability, and open-protocol standards are needed for data-driven lighting systems to be of value. He emphasized the amount of time and money needed to start, maintain, and leverage the data and savings offered by advanced lighting systems.

Sarah Dreger of Stantec focused on the future of building technology, including generative design, machine learning, and digital twins. Stantec, one of the largest architecture + engineering firms in the U.S., is focused on leveraging technology to deliver a better experience and overall product to clients. A digital twin is developed for almost every current project. Increasingly, reality capture is also being used as a way to field-verify construction as well as for retrofit projects. Dreger noted that clients want to be more engaged in the design process and want to understand why decisions are being made relative to the building. In response, Stantec recently developed a tool to help clients understand how adjusting different design variables affects energy, cost, and other benefits, by letting the clients adjust the different variables and using data from their current facilities. Dreger emphasized that we are no longer waiting for technology to catch up in order to do what we want to do, and that the time is now.

Lighting for Grid-Interactive Efficient Buildings

Michael Poplawski moderated a panel discussion that provided a view into utility demand-response (DR) programs, and the challenges and potential for connected lighting systems (CLS) to play a role in that market. The panel looked at connected lighting in the context of grid-interactive efficient buildings (GEBs), reviewed the financial exchanges and grid-service outcomes that have occurred in the DR market in recent years, and presented preliminary simulation results that characterize the ability of CLS to deliver grid services while simultaneously delivering sufficient lighting service and occupant satisfaction.

David Nemtzow discussed how DOE views buildings as grid-interactive efficient assets that can optimize the interplay between their loads and the electric grid. New technologies and research can enable lighting and other building systems to build upon their existing energy-efficient platforms with an enhanced understanding of grid and occupant needs. He noted that homes and buildings cost the U.S. nearly $395 billion a year to power, consume almost 39% of the nation’s energy and more than 74% of its electricity, and contribute to 40% of our greenhouse-gas emissions – representing a huge opportunity for further savings. The benefits of GEBs include energy affordability, improved reliability, reduced grid congestion, enhanced services, environmental benefits, and customer choice.

Debyani Ghosh of Navigant discussed the role of lighting in the demand-response market, highlighting the challenges and opportunities. She noted that energy-only cost-effectiveness of DR-enabled lighting systems varies by building size and service territory. For example, in the Pacific Gas & Electric Company’s service territory, where commercial retail electricity rates are relatively high (especially on-peak), there is a net benefit across all building sizes and types. By contrast, in Southern California Edison’s service territory, where electricity rates are lower, the cost-effectiveness depends strongly on the building size, with a net benefit for large buildings only. Ghosh stated that the primary value proposition for DR-enabled lighting systems comes from the site-level energy savings that are realized with or without DR participation.

Poplawski described how CLS flexibility for providing grid services can be modeled by five key parameters that account for building types and lighting applications, CLS characteristics, and occupant satisfaction: maximum lighting load, nominal lighting load, minimal lighting load, lighting-load change delay, and maximum lighting-load ramp rate. He reviewed the recent results of PNNL’s simulation study, which showed how a medium office building might provide grid service in the form of demand reduction resulting from the response to near real-time electricity prices. Simulation results showed that CLS responding to real-world five-minute prices might deliver ~40% of the maximum potential energy savings over a five-day trial period.

Connected Lighting System Value

Michael Poplawski moderated a panel discussion that took a deep dive into a few of the benefits of connected lighting systems and their associated costs and risks, and that also considered what’s next, based on what researchers and early adopters are currently exploring in the laboratory and in the field.

Farukh Aslam of Sinclair Holdings described the ways connectivity is being used at his company’s Sinclair Autograph Hotel, which features digital electricity, battery storage, PoE power, and sensing. Digital electricity distributes large amounts of electricity over 18/2 cables in packets, with Class 2 power that’s safe to handle, eliminating the need for an electrician to install, and with intelligent load-shedding capabilities to distribute power based on priority in the event of a power outage. PoE switches fed by digital electricity provide both low-voltage DC power and network communication to lighting, window shades and curtains, mini bars, smart mirrors, and door locks, thereby eliminating the need for AC/DC power conversion in the end-use devices. A centralized energy-storage system features a lithium ion battery pack instead of a diesel generator for emergency power backup.  

Peter Brown of Lighting Transitions discussed the connected-lighting megatrends of digitalization and adoption, including some implications and suggested paths forward. He noted that connected lighting does not easily fit into the existing channel model of OEM/rep/distributor/contractor/end user, and that it’s disruptive to both existing lighting buyers and IT. Brown said non-CLS adoption continues to accelerate at CLS’s expense, and pointed out that mass adoption is historically driven by user values rather than by product features. He stated that tunable lighting remains a niche product, due to poor baselines in the majority of sites, and that a lack of lighting-industry standards (security, IoT platforms, health) for connected lighting continues to impede adoption.