Growing Impact: In-tune lighting

Growing Impact: In-Tune Lighting

Julian Wang and Anne-Marie Chang discuss their seed grant project that investigates how indoor lighting can be adjusted to save energy on a building’s heating and cooling and positively impact human health.

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INTRO: Humans will have responses to the lighting conditions and intensity and colors. So that will affect the human’s visual comfort, working productivity, efficiency, and even health.

HOST: Welcome to Growing Impact. A podcast by the Institutes of Energy and the Environment at Penn State. Growing Impact explores cutting-edge projects of researchers and scientists who are solving some of the world's most challenging energy and environmental issues. Each project has been funded through an innovative seed grant program that is facilitated through IEE. I'm your host, Kevin Sliman.

Today on Growing Impact, I speak with Julian Wang, an Associate Professor of Architectural Engineering, and Anne-Marie Chang, an Associate Professor of Biobehavioral Health, about their project titled “Building Energy Savings by Tuning Indoor Lighting.” Their project explores how lighting can be adjusted in order to help reduce energy usage and positively impact human health.

Welcome to the Growing Impact Podcast, Julian Wang and Anne-Marie Chang.

Julian Wang (JW): Thanks for having me, this is Julian.

Anne-Marie Chang (AC): Yes, it’s a pleasure to be here, thanks.

HOST: Let's start talking about your project. Why is it important then to be thinking about indoor lighting?

JW: Yeah, I can start with this question. So the indoor lighting has, from the research perspective and also the daily living perspective, it has two major impacts. The one is about building energy. Based on the Energy Information Administration data, about 20% of energy use of a building is contributed by lighting – indoor lighting, electrical lighting, electrical luminaries. So residential building maybe a little bit lower than 20% and a commercial building might be a little bit higher than that, but these average rates are around 20%. And it’s not only about the lighting from an energy perspective, even from traditional perspective, lighting are illuminators. So we'll also bring some heat gains to indoor environments that will further change the HVAC, the air conditioning, energy consumption.

And the second aspect about lighting impact, I think is about humans. So indoor occupants, humans will have responses to the lighting conditions and intensity and colors. So that will affect the human’s visual comfort, working productivity, efficiency, and even health. So Anne-Marie has some previous studies on that. So Anne-Marie, maybe you want to introduce more about that?

AC: Sure, sure. So my research has looked at aspects of light and indoor light and how those environmental cues affect things like human circadian rhythms. And also how people perceive their moods, how people perceive their alertness or sleepiness, and really daily activities, and how those are affected and their responses to the lighting environment.

HOST: I read in the title talking about “tuning” indoor lighting. Can you talk a little bit about tuning it and what that means?

JW: Yeah. So you know that the traditional lighting system, so they are kind of just switch-on, switch-off. But now, what we call solid-state lighting technology, LED is a part of that. So this kind of technology has evolved in terms of better luminaire architecture and also more advanced control technologies. So now the indoor lighting can be tuned to deliver much more flexible and robust options.

HOST: So what is your project examining?

JW: In this work, we particularly look at the thermal response. So we did mention energy and human response in regular heat gains from luminaires to the thermal environment. But actually, in this work, we look at the human thermal response to tuning, to the tuning of indoor lighting. So in simple words, the red light is perceived a little bit hotter, and blue light is perceived in the opposite way. In our project, we would like to directly work with the human subjects, within a thermal chamber and more accurate lighting spectral and intensity controls. So more importantly, we want to examine the inner spectral, or we can call it color, inner color and intensity compositions, rather than lighting appearance. In our hypothesis, we think the major stimulators, or we can call actuators, of thermal response are not lighting appearance, but rather inside or inner radiometry content like the color and intensity, the inner side of each color. We can compose the different things that have very similar appearance of light. So we're looking at the inner part rather than appearance. We like to control the lighting appearance to be weaving, kind of appropriate range, but we do very different in inner spectral or color compositions.

HOST: So now the million question is, why? Why do you want to look at this and what do you suppose can, what can be affected by these changes?

JW: Right. So yeah, we know in order to maintain user indoor satisfaction or indoor comfort, the temperature set points for heating and cooling systems must be adjusted to meet thermal comfort needs, like our thermostat on the wall, right? So we need to change that to meet our thermal comfort needs. So if the hypothesis that we mentioned, would be appropriate for a range of lighting appearance if the lighting, the inner spectral composition can change human thermal response. So some lighting condition can make people feel a little bit cooler. Some of them make people feel a little bit warmer. Then we can basically widen the temperature settings, right?

So we did some preliminary energy analysis. If we widen the temperature set points, how much energy we can reduce. So our preliminary analysis demonstrated this, widening the cooling and heating thermostat set points by just one Celsius degree could save air conditioning energy use 7 to 15%. More than that, if it's a three or four Celsius degree expansion, could reach more than 30 or 40%.

HOST: That's significant. Yeah. From changing the way that the lighting is, the way our brains are, our eyes are, et cetera, are perceiving light. That's amazing.

AC: Right. And that's really based on a perception, too, that an individual might not even notice. Right? So they wouldn't notice the change in the lighting when you tune it to just a slight difference in the inner spectral composition. And they might not actually realize that they have an altered response, thermal response to that lighting. So they may perceive it as they’re just going about their daily, within their comfort range thermally, they're just going about their daily lives or their work the way they usually do without even noticing this change. That could have a huge impact for energy savings.

HOST: Oh yeah, so let's talk about scalability. Are you looking at residential or are you looking at larger buildings or a little bit of both> And then how scalable is it?

JW: So this is a very good question. So from the technology perspective, I don't think it's complicated, once we confirm the concept. But we do have some questions like a different person may have a different feelings to those things and we are not serving this kind of technology for individuals. We work for the group of people in the building, so that may bring some questions. We also need to address those, before that before we scale up to the real application. Yeah. And also back to the second part of your question, for the commercial and residential. I think from the energy-saving perspective, commercial building might be a target for us. Because based on the lighting energy consumption fraction, that one is a little bit higher than the residential buildings, and we probably can save more energy if we use that in the commercial building rather than residential.

AC: But this could have very significant implications for human health. And considering things like thermal comfort for sleep. You know, that application could also be extended, I think, and there are really great potential opportunities for looking at residential use. Even though you might see a smaller scale in terms of the energy efficiency, compared to a commercial building. This could have a real impact in the consumer perspective of people in their homes wanting thermal comfort.

JW: Right, I agree. So yeah, I agree. So this kind of technology, once we prove the concept, it can be integrated into other lighting technologies for human health-related things. Like for nursing homes, they are already using some bright lights to deliver the bright light for residents to give them more exposure to daylight, that is simulating daylight. So something like that probably we can incorporate these kind of things into there, to not only about thermal response, also related to the general human health and also well-being.

HOST: Can we talk about the interdisciplinary aspect of this? Why does a project like this benefit from an interdisciplinary team and looking at it from different directions, and maybe talk about some of those different areas where you need expertise?

AC: I feel like the opportunity to learn is so great in this type of seed grant call. Because the expertise that each of us bring to the project not only fills in the gaps that exist in our own specific fields, but I think the most exciting science happens when you have overlap of different fields and different disciplines. And at those edges of overlap is where you really push fields forward. And so Julian comes with a perspective and an understanding and an expertise of lighting and engineering that is so novel to me. But yet I understand aspects of it with regards to lighting. And so it, I think, really adds a robustness and a rigor to this research that incorporates these different perspectives.

JW: I just want to add two more feelings I have in this procedure. One is about interpretation. Interpretation of a scientific question is, you know, the interpreting the research results or findings is crucial for both the outside public awareness and also the inside of research domains with the help from experts in other areas. So this can be achieved much smoothly and clearly to interpret the results. Give more sense to the content. In more interpretable explanations. And another feeling I have is kind of an efficient problem-solving procedure. I was having some questions when I was working my part, when I was trying to design experiments or working on the protocols of human studies, or working on instruments, some other things. So we can easily get a solution and effective comments from Anne-Marie or from other faculty members, the other investigators, the other areas. We do have the kinesiology, biobehavior – AnneMarie -- and also the electrical engineering and architectural engineering. So we can have this interdisciplinary incorporation can give us very effective and efficient problem-solving procedure is much easier.

HOST: What do you hope this project can achieve?

JW: At this stage, we just want to prove the concept with a small sample size. Once we have those results we will have kind of an in-depth discussion based on the results obtained from this seed funding project. And to see how we can develop or generate a new hypothesis or more comprehensive hypothesis, or accurate hypothesis, to design those things for next step. Once we have that, we want to pursue external opportunities to work on a more comprehensive view of this project, involve more participants in the experiments and even put them into the real testbed to see the human response and energy-saving at the same time.

AC: For me, that would be the most exciting part. To look at the results, preliminary results, and really generate hypotheses going forward. Because I think that's an exciting, it really opens up a lot of opportunities and potential paths to follow.

HOST: I appreciate you both taking time to speak with me today about your project.

JW: All right. Thank you.

AC: It was a pleasure.

HOST: You have been listening to Growing Impact a podcast by the Institutes of Energy and the Environment at Penn State. I’ve been your host, Kevin Sliman. This has been season 2, episode 2. Thank you for listening