The building is unassuming, tucked next to a sleepy road in Davis away from the main campus. Fashioned from cinderblocks and topped with a red brick-colored roof, it looks like a building you’d find in countless business parks across anywhere, USA. 

But something vibrant is happening within this building’s walls. Inside is the home of the UC Davis California Lighting Technology Center (CLTC), a research, development and demonstration facility with an over 20-year history. 

At the CLTC, lighting technology isn’t just about aesthetics; it’s a pertinent part of everyday life. Not only does lighting influence our body’s natural rhythm, but it also affects the health of our energy grids. As society explores alternative and renewable energy sources, the CLTC aims to be a guiding beacon, showcasing through research and design the best ways to integrate efficient and human-centric energy systems into new and existing infrastructure. 

But doing that doesn’t just require buy-in from industry and governments. It requires buy-in from everyday people. 

“Even if you develop an amazing technology, if people aren’t comfortable with it, the technology is not accepted,” said Jae Yong Suk, faculty co-director of CLTC and an associate professor of design. “It’s essential that we design the technology with the human experience in mind.” 

On a rainy day in November, Suk led a tour through the CLTC and highlighted the facility’s myriad projects to develop and commercialize new energy and building technology that’s designed with considerations towards decarbonization, grid resiliency and community well-being.

CLTC is a place where real-world impacts are being made. We bridge the gaps between academia, industry and government to push society towards a sustainable and resilient future, developing new technology and policy guidelines via multidisciplinary research collaborations. — Jae Yong Suk

Human-centric lighting

The human body is tuned to light. It regulates our circadian rhythm, influencing the production of hormones like melatonin, which is key to healthy sleep-wake cycles. The artificial lighting of our modern world can negatively affect this natural rhythm. Fluorescents, light-emitting diodes (LEDs) and smartphones, among other technologies, expel blue light. While necessary during the day, light at this wavelength impedes the body’s natural processes.

“In the daytime, especially in the morning, our body needs this high intensity, blue light exposure, but if you have it at night, it’s going to mess with your sleep,” Suk said.       

In health-oriented settings like hospitals, where patients have limited to no control over lighting, blue light can be a disruptive force. That’s why the CLTC partnered with UC Davis Health to design lighting systems that promote human circadian rhythm. 

At the CLTC, multiple spaces are dedicated to this project. There’s a hallway that mimics a hospital corridor, a space that looks like a patient care room and a mock nursing station. All are equipped with tunable white lighting. 

“If we have blue spectrum on at night inside a hospital corridor and then it spills into a patient’s room and the patient perceives that light, their melatonin can be suppressed,” Suk said. “So depending on the time of day, buildings should change indoor lighting conditions between blue spectrum, higher blue spectrum or no blue spectrum.”   

At night, the lighting fixtures can be adjusted to emit photons in the amber spectrum, which doesn’t disrupt melatonin production, leading to a smooth circadian rhythm. While a patient might prefer amber spectrum lighting to minimize sleep disruption, nurses on the night shift might prefer blue spectrum lighting at the nursing station. With the CLTC’s design, both options are available. 

Lights on, lights off

In a room near the CLTC’s mock hospital corridor, an engineer fiddled with a laptop and robot. Blue tape was fastened to the floor in a grid-like pattern. White markers peppered the path. At first glance, it’s hard to tell what it’s all for. But it’s a part of putting the human at the center of design. 

Dovetailing with CLTC’s circadian lighting design project are efforts to advance occupancy sensors and lighting control technology. Occupancy sensors automatically adjust lighting based on movement. Such technology can lead to more efficient energy usage and cost savings. 

“This robot follows the blue tape and then stops at the markers and waves its arm to test the acute position for accuracy,” Suk explained.     

Currently, Suk and colleagues are working with UC Davis Health to integrate their circadian lighting design into the infrastructure of the California Tower, a 14-story addition to the UC Davis Medical Center that’s slated for completion in 2030. 

“We’ve had meetings with UC Davis Medical Center, the architects, the interior designers, the lighting designers and the contractors so they understand the importance of circadian lighting,” Suk said. “Our role is to help maintain that focus.”   

Mitigating stress in The Color Lab

Beyond design, CLTC also conducts foundational research on the effects of light on human behavior and mood. Last year, they partnered with the Center for Mind and Brain to uncover how different colors of light affect stress. The research — supported by Toyota Boshoku America, Seoul Semiconductor and Color Kinetics — led to the creation of The Color Lab.

To determine how light affects stress, CLTC researchers recorded study participants’ brain wave patterns and collected saliva samples, using the latter to measure biomarkers associated with stress. After getting a baseline, the researchers then placed participants at the front of a room under bright lights. Participants were then asked to publicly speak before a panel of judges garbed in white and wearing masks. The situation was meant to elicit a stress response. 

“After we stressed the participant, we bring them into The Color Lab, where they’re seated and wait for 30 minutes under a specific ambient light condition,” Suk said.  

Suk said the team ran the experiment on more than 100 participants, testing the effects of white, amber, red, green and blue light on stress.

“We actually found that the amber lighting is beneficial for stress mitigation compared to white light, which is our basic reference point,” Suk said. “All the other colors, like blue, red and green show slower stress recovery compared to white.”   

The Color Lab also runs experiments dedicated to uncovering how different sources of light influence human perception of color. This is of particular importance to places like museums and art galleries.  

“We’re trying to understand how people perceive sunlight versus traditional LED lights,” Suk said. “You can imagine that for places like the Manetti Shrem Museum of Art having the right light spectrum is important because you don’t want people perceiving the wrong color.”   

An eye on energy and grid resiliency 

Situated near the center of the CLTC building is a replica of a small single-family house. Though the frame doesn’t have a roof, its innards contain a kitchen, living room, bathroom, bedroom and a utility room for a washer/dryer. The replica is part of CLTC’s research on smart home technology.    

“We have expanded our research capacity beyond lighting at the California Lighting Technology Center,” Suk said. “Our project portfolio now includes a lot of building controls technology with lighting being just one of the components.”  

Funded by Panasonic and Japan’s New Energy and Industrial Technology Development Organization, Suk and colleagues are developing a smart home energy kit that monitors the energy consumption of all electric appliances in a household. The project is called the Virtual Home Energy Management Systems.   

“In California, we have two different electricity rates: peak hours and non-peak hours,” Suk explained. “If you operate all the appliances during peak hours, it’s going to be expensive, but peak hours in the state help us to avoid operating appliances at the same time. We don’t want to overload the capacity of the grid and have a power outage.” 

With the smart home energy kit, the CLTC is developing a system that monitors a homeowner’s energy usage and provides recommendations to save money or conserve energy and reduce carbon emissions.  

“Some people care about saving money, while others want to help the planet,” Suk said. “Our interactive system can provide information to help with either goal.”   

Partnering with SMUD, the CLTC has outfitted seven buildings in Sacramento with the system. The team monitors energy usage in the buildings and works with the occupants to better understand human-computer interactions, both positive and negative.   

The hope is to develop strategies that not only benefit the customer but also reduce building energy use and carbon emissions. The project is just a facet of the CLTC’s broad research portfolio that expands beyond lighting into whole building systems and energy efficiency.  

For the past twenty years, CLTC has been recognized as the world’s leading lighting research institution. In the next twenty years, we will take the center to the next phase that seamlessly integrates and expands our lighting technology expertise into smart building energy controls and automation, grid resiliency, and community wellbeing. We are excited to see how the center will evolve in the future. — Jae Yong Suk

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