DOE lighting workshop explores lighting science and systems
Article By : Yoelit Hiebert
This year’s DOE Lighting R&D Workshop covered topics like lighting for plants and human health, and integration of lighting and controls into new construction.
The 2020 DOE Office of Energy Efficiency and Renewable Energy (EERE) Lighting R&D Workshop, held January 28-30, 2020 in San Diego, featured a notable change from years past, specifically, a broadened conference scope. While previous workshops have focused on LED chip-scale and package-scale technology, especially in the area of efficacy improvements, the scope of this year’s conference included tracks for lighting science and lighting systems. General sessions covered topics like LED lighting adoption and resulting energy savings, lighting for plants and animals, lighting for human health and well-being, and integration of lighting and controls into new construction.
The conference began with a recap of the main reason businesses and home owners are switching to LED lighting: lower energy costs. The DOE estimates that by 2035, LED lighting is expected to be the dominant technology in 84% of all lighting installations with a resulting cumulative savings of 62 quads.
One of the most impressive presentations came from the Utah State University Department of Plants, Soils and Climate, who have been working with NASA in developing methods for growing food on Mars. Since food will need to be grown underground, artificial lighting will be a key component in the food production system. LED lighting is the obvious choice, not only for its lower power requirements, but also for its ability to be precisely tuned to the optimal spectrum for each type of plant being grown. Work on defining the best “light recipe” for each developmental stage of each species of plant is on-going at Utah State, as well as at a number of other institutions throughout the country, and will no doubt have implications for indoor grow facilities here on Earth as changes in weather patterns disrupt our ability to reliably grow food outdoors.
Another engrossing talk came from Stanford University’s Department of Psychiatry and Behavioral Science. This presentation focused on the limits of using LED lighting to adjust circadian rhythm response in humans. The goal of the study described in the talk was to determine the effectiveness of a specific light protocol in helping adolescents get more sleep. The study subjects were exposed to differing light regimens and the resulting shifts in circadian rhythm were assessed. At the end of the study, the researchers found that although the light exposure had its intended physiological impact, that is, circadian rhythms had indeed shifted, the teenagers involved did not, in fact, end up getting more sleep.
Unsurprisingly, even though they felt more tired, they were still unwilling to go to bed any earlier than before because all their friends were still up. The study concluded that simply adjusting circadian rhythm was not sufficient to result in the desired outcome, i.e., getting more sleep. As human-centric lighting is increasingly incorporated into our work and home environments, we should be mindful that the objective is to modify behavior, be it turning in earlier, being more productive at work, or taking fewer sick days, and that changes to lighting alone may not have the intended result.
Turning to LED technology, the DOE estimates that the current state-of-the-art for LED lighting, from a performance standpoint, is only about half of what can ultimately be achieved (Figure 1).
Figure 1 This chart shows efficacies and efficiencies of white and color LED packages over time. Source: DOE Office of Energy Efficiency and Renewable Energy
Other presentations covered topics that spanned the current range of solid-state-lighting technologies like semiconductor materials, quantum dots, and OLEDs. There is growing interest in the use of quantum dots to enhance red emissions by incorporating them into LED packages used for general illumination. The challenges in terms of materials and construction in implementing this strategy were explored in one presentation. Another presentation provided an overview of the use of quantum dots for displays. In the area of OLED technology, a discussion of the potential of diluting the organic compounds in OLED devices with an insulator like Teflon was explored as a means of reducing the amount of semiconductor material required without sacrificing electrical transport.
There was an undeniable emphasis at this year’s conference on lighting as it relates to building construction, controls, and networked building systems that reflects the shifting focus of the EERE. This expansion of conference scope is not unexpected given that there seems to be increasing agreement in the industry that the energy efficiency gains due to LED lighting conversions have probably reached a peak. How this reconciles with EERE claims that significant improvements in device efficacy are still attainable remains to be seen.
—Yoelit Hiebert has worked in the field of LED lighting for the past 10 years and has experience in both the manufacturing and end-user sides of the industry.
