Subtle white light changes make indoor rooms feel cooler or warmer

Slightly changing the wavelength of light may influence how people feel indoors without changing the temperature, new research suggests

Penn State

Facebook

XLinkedInWeChatBlueskyMessageWhatsAppEmail

 

image: 

A new study led by scientists at Penn State found that white light can impact how people experience indoor temperatures. Although the wavelength differences are invisible to the human eyes, they can influence the gap between perceived and real temperature by as much as 1.3 degrees Fahrenheit (F). 

view more 

Credit: Courtesy of Julian Wang / Penn State

UNIVERSITY PARK, Pa. — Feeling too warm or too cold indoors may depend on more than the thermostat. The spectrum of indoor lighting plays a role in how people perceive temperature, according to research led by scientists at Penn State.

In a study, available in the August issue of the journal Energy and Buildings, researchers found that controlling red and blue wavelengths — two of the bandwidths of electromagnetic radiation that flow through space and are perceived by humans as light — of white light can impact how people experience indoor temperatures. Although the wavelength differences are invisible to the human eyes, they can influence the gap between perceived and real temperature by as much as 1.3 degrees Fahrenheit (F).

According to Julian Wang, professor of architectural engineering at Penn State and principal investigator of the study, if certain lighting conditions allow people to feel comfortable across a wider range of temperatures, that could help reduce heating and cooling demands and ultimately lead to energy savings.

‘‘We wanted to understand whether lighting can widen people's thermal comfort zone,” Wang said. “If it can, even a modest shift in perceived temperature can translate into substantial cumulative energy savings over time.’’

Previous studies have shown that colored lighting, such as blue and red light, can influence thermal perception, he said. However, colored lighting is impractical for everyday environments such as offices, classrooms, and homes because it can be visually distracting and create visual noise, making it difficult to perform routine tasks comfortably. Through this project, Wang's team found that the “color” doesn’t need to be visible to achieve the same effects — subtle differences hidden within ordinary white light can produce similar effects without changing the appearance of the lighting.

‘‘The novelty of this study is that we used white light that looks identical to the human eye but has a different spectral composition,’’ Wang said, explaining that their findings provide some of the first evidence that different white light spectra can influence how people perceive indoor temperatures. ‘‘That allowed us to evaluate whether the response was driven by thespectral composition of the light, rather than by people's perception of color.’’

To test this idea, the researchers recruited 10 participants, five women and five men, between the ages of 18 and 35. Participants occupied a simulated office cubicle inside a climate-controlled chamber at Penn State’s University Park campus while experiencing gradually increasing and decreasing air temperature cycles starting from an initial room temperature of approximately 76°F. During the separate experimental sessions, participants were exposed to two types of white light that looked identical but differed in their dominant wavelengths: one enriched in blue short-wave light and the other enriched in red long-wave light. Throughout the study, the researchers monitored participants' thermal sensation, comfort and behavioral responses.

The researchers found that when participants were exposed to blue-enriched white light in the controlled room, they felt cool enough to tolerate air temperatures about 1.3 F warmer. In contrast, red-enriched white light had the opposite effect, making participants feel warmer.

While the findings are promising, Wang said, this was an exploratory study. In the future, the team plans to expand the research to see whether the results are consistent when utilizing participants from a wider range of backgrounds and age groups. They said they also hope to investigate how lighting interacts with other environmental factors, such as sound, window views and visual patterns, to shape people's perception of indoor comfort.

‘‘The next step is to do research in a larger and more diverse population to determine whether these effects extend beyond young adults and could be applied globally,” Wang said.

Ultimately, he said his group plans to test the new lighting strategies under more extreme heat and cold conditions and evaluate how they could be incorporated into real-world buildings to improve comfort while reducing energy use.

‘‘This is just one of our starting points,’’ he said. ‘‘Our long-term goal is to expand people's multi-domain interactions, and if successful, this approach could improve comfort and human performance while reducing energy use in buildings, from homes and offices to space habitats.’’

This research was funded by the Institute of Energy and the Environment (IEE) Seed Grant at Penn State.

Study collaborators include Jeffrey Muninger and Chenshun Chen, postdoctoral scholars in architectural engineering from Penn State; Anne-Marie Chang, associate professor of biobehavioral health at Penn State; first author Nan Wang, a postdoctoral scholar in civil and environmental engineering at Northwestern University; and Yanxiao Feng from the New Jersey Institute of Technology.

---

Journal

Energy and Buildings

DOI

10.1016/j.enbuild.2026.117644 

Method of Research

Experimental study

Subject of Research

People

Article Title

Effects of metameric light on human subjective and behavioral thermal responses in daytime transient thermal environments

Article Publication Date

21-Aug-2026

 

The clean energy transition’s missing metric: human health

Columbia University's Mailman School of Public Health

Facebook

XLinkedInWeChatBlueskyMessageWhatsAppEmail

Earlier this year, the First Conference on Transitioning Away from Fossil Fuels, in Santa Marta, Colombia, convened representatives from 57 countries to advance a just, orderly, and equitable transition to green energy. According to a new correspondence published in The Lancet, while the conference’s final report makes a powerful case for a rapid global phase-out, “it overlooks the extraordinary health and health-economic benefits of doing so.”

In the letter, Robbie Parks, PhD, assistant professor of environmental health sciences at Columbia University Mailman School of Public Health, and six co-authors explain that the transition away from fossil fuels offers a quintuple win: healthier populations, enhanced energy security, cleaner environments, more resilient and affordable health systems, and effective climate mitigation.

The authors, who are scholars and scientists in sustainability, climate action, communications, and environmental health, offer three concrete recommendations for bringing health into planning for the green transition:

1. National leaders should convene national dialogues to assess the health harms of fossil fuels and the benefits of phase-out, and to shape transition policies that maximize health, equity, energy security, resilience, and climate gains.
2. The health community should be appropriately resourced to support these dialogues by identifying and quantifying avoidable health harms, health benefits of phase-out, and associated economic returns.
3. The health community must build structures needed to upskill rapidly at scale and to translate research into policy and advocacy efforts required to counter multibillion-dollar fossil fuel public relations, misinformation, and lobbying.

“We must make the case—to the public and policymakers at all levels—that phase-out prevents illness, saves lives, and helps stabilize the supply chains, electricity grids, water supplies, health-care infrastructure, and health workforce on which functioning health systems depend. Metrics and narratives grounded in community harms resonate with lived experience, counter disinformation, and frame the transition around shared prosperity and wellbeing,” the authors write.

Additional co-authors include Julianna Gwiszcz and Edward Maibach, George Mason University; Jessica Newberry Le Vay, University of Oxford; Ebba Malmqvist, Lund University; Courtney  Howard, University of Calgary and York University; and Marina Romanello, University College London.

---

Journal

The Lancet

DOI

10.1016/S0140-6736(26)01538-2. 

Method of Research

Commentary/editorial

Subject of Research

People

Article Title

Health should be key to transitioning away from fossil fuels

Article Publication Date

19-Aug-2026

 

Hot temperatures can change the configuration of tiny structures, such as the scales of the dazzling Morpho butterflies

Smithsonian Tropical Research Institute

Facebook

XLinkedInWeChatBlueskyMessageWhatsAppEmail

 

image: 

The iridescent blue color we see in Morpho butterflies is a consequence of how the light is reflected on the very tiny structures that form their wing scales, which are like tiles overlapped on a roof.

view more 

Credit: Connor Evans-Blake

Blue Morpho butterflies have captivated the human eye for centuries: we even have one as an emoji on our phones! In a recent experiment, researchers at the Smithsonian Tropical Research Institute (STRI) documented for the first time that hot temperatures during their development can reduce the brightness of their iridescence. In hot temperatures, such as those projected in warming future scenarios, the structures responsible for their iridescent color could change enough that common bird predators and other butterflies from the same species would likely see a color change. Scientists gathered their results in a recent publication in the journal Proceedings of the National Academy of Sciences Nexus. 

Scientists exposed Morpho helenor pupae, the stage of metamorphosis before adulthood, to three different temperature categories: average tropical temperature, in which these butterflies normally live, temperate temperature, simulating temperatures in temperate zones, and hot temperatures, such as those predicted by climate change.  

Consistent with other studies, they found that temperate and hot temperatures extend the time they spend as pupae. Moreover, in hot temperatures pupae died more often. They also found that adult Morpho butterflies from hot temperatures were duller, and that common bird predators and butterflies from the same species could detect a color change. The effects of this color change on predators or possible partners is still unknown. As iridescence might confuse predators, duller or color-altered butterflies might be more susceptible to predation or less attractive for possible mates. 

“Here we show that iridescent animals are susceptible to the environmental conditions in which they develop. Under a warming climate, the color of some of our favorite iridescent animals can be altered and the brightness of their iridescent display dulls,” explained lead author of the study and STRI fellow Juliette Rubin.  

The blue iridescent color we see in Morpho butterflies doesn’t come from pigments. It comes from very tiny, ridged structures on the scales of their wings called nanostructures. The blue color we see is a product of how the light is reflected by these microscopic pieces. “The scales on these butterflies are like tiles overlapping on a roof. The change in color we found in adults after exposing pupae to hot temperatures can be partly explained by the distance between nanostructures shrinking, narrowing the entire scale,” explained Rubin. “This probably caused less overlapping between the scales.” 

The results of this study might help make predictions about the effects of raising temperatures in the development of different animals. Overall, the flexibility of these tiny structures is surprising, revealing how even the smallest natural designs can respond to a changing climate. 

“This study would not have been possible without STRI’s facilities and laboratories located within the natural, tropical distribution of these dazzling butterflies, offering a unique opportunity to perform our experiments. STRI also provided the chance to work with fellows and interns from multiple countries, creating a collaborative team of curious scientists,” added Rubin. 

Reference: Rubin, J. J., Camino, L. T., López-Tacoaman, Y. F., Wagh, P. R., Hernández Campos, G. C., & McMillan, W. O. 2026. Hot temperature during development alters iridescence in Morpho butterflies. PNAS Nexus, 5(8), pgag243. https://doi.org/10.1093/pnasnexus/pgag243 

 

About the Smithsonian Tropical Research Institute 

Headquartered in Panama City, Panama, STRI is a unit of the Smithsonian Institution. Our mission is to understand tropical biodiversity and its importance to human welfare, to train students to conduct research in the tropics and to promote conservation by increasing public awareness of the beauty and importance of tropical ecosystems. Watch our video, and visit our website, Facebook and Instagram for updates. 

---

Article Title

Hot temperature during development alters iridescence in Morpho butterflies

Adult Morpho butterfly recently hatched from its pupa.

Credit

Connor Evans-Blake

Lead author of the study and STRI fellow Juliette Rubin.

Credit

Juliette Rubin

 

Innovative metasurfaces offer a new way to block radiant heat

Scientists have developed pairs of ultrathin, nonmetallic coatings that work together to reduce heat transfer

Advanced Science Research Center, GC/CUNY

Facebook

XLinkedInWeChatBlueskyMessageWhatsAppEmail

 

image: 

The proposed metasurface pair with complementary design for broadband suppression of radiative heat transfer (right), compared with a benchmark pair of silica substrates exhibiting broadband radiative exchange (left), and traditional narrowband spectral engineering (center), which is subject to Bode-Fano limitations.

view more 

Credit: Lin Jing

New York, August 20, 2026 — Researchers at the Advanced Science Research Center at the CUNY Graduate Center (CUNY ASRC) and Honeywell Aerospace have developed a new way to reduce the transfer of radiant heat between closely spaced bodies by using thin, nonmetallic coatings. In laboratory tests, the novel metasurface reduced thermal radiation emission by over 80% compared to nonstructured surfaces made of the same dielectric materials. The system also maintained its performance across a wide range of operating temperatures and showed resilience to small variations that could occur during design and fabrication.

“Our findings demonstrate the value of looking at thermal radiation as a system-level interaction,” said principal investigator Andrea Alù, director of the CUNY ASRC Photonics Initiative and Distinguished and Einstein Professor of Physics at the CUNY Graduate Center. “Instead of asking how to make a single nonmetallic surface reflect everything, we asked how two surfaces could be designed to exchange as little energy as possible. That shift in perspective allowed us to overcome longstanding bandwidth restrictions associated with conventional approaches.”

The new approach, resulting from an academic/industry partnership between the CUNY ASRC Photonics Initiative and Honeywell Aerospace’s Advanced Cryogenics Platform Group, was detailed in a recently published paper in Nature Communications. It will improve thermal insulation and temperature control in electronic devices, infrared sensors, spacecraft components and other technologies where conventional metallic coatings may create problems.

All objects emit energy in the form of thermal radiation. At temperatures encountered in most technologies, much of this energy travels as invisible infrared light. When two objects face each other, each surface emits infrared radiation that can be absorbed by the other, allowing heat to move between them when they are at different temperatures even when they are not touching.

Metallic coatings are commonly used to limit this exchange because metals reflect infrared light across a broad range of wavelengths. But metals also conduct electricity and may interfere with sensitive electronic, optical or thermoelectric systems. They can also be difficult to combine with other materials in integrated systems.

Nonmetallic photonic coatings offer an alternative, but existing designs generally face a trade-off. They may block thermal radiation strongly across a narrow range of wavelengths, or work across a broader range only if they are made very thick, posing challenges in practical technologies.

Instead of trying to make a perfect infrared reflector from a single surface, the research team addressed the problem by designing and combining pairs of thin coatings.

“The key was to stop treating the two surfaces as separate design problems,” said co-lead author Lin Jing, a post-doctoral researcher with the CUNY ASRC Photonics Initiative. “We designed them as a coordinated pair so that when one surface emits efficiently at multiple selected wavelengths, the other surface is deliberately poor at absorbing those wavelengths.”

The concept is like two radios tuned to different channels. Each radio can transmit and receive, but because they operate on different frequencies, they communicate very little with each other.

For their study, the researchers created a pair of metasurfaces that were engineered to control light. Each metasurface consisted of seven thin layers of nonmetallic, dielectric materials. The layers formed structures known as distributed Bragg reflectors, which can reflect or transmit selected wavelengths of light.

“Traditional distributed Bragg reflectors can exceed the reflectivity of metals; but only over limited bandwidths, which isn’t good for preventing heat transfer over a broad spectrum,” said Honeywell Aerospace principal investigator Tim Palinski. “Using our spectral mismatching technique, we can tolerate high emission from one surface in one band, as long as it is reflected by the other surface in the same band.”

“This complementary design allows us to keep the structures compact, and it also uses a relatively straightforward layered design that can be produced through established thin-film deposition techniques without requiring complex nanoscale patterning,” said co-lead author Mingze He, also a post-doctoral researcher with the CUNY ASRC Photonics Initiative.”

“I am also particularly excited to see this important result stemming from a strong synergy between industry and academia,” said Alù. “This result would not have been possible without the close collaboration with our Honeywell Aerospace colleagues, who inspired the problem and helped us with developing the concept and bringing it to fruition with careful measurements.”

Additional testing is planned for the technology, which is at the proof-of-concept stage.

“This collaboration brought together the CUNY ASRC team’s expertise in photonic design and optimization with our experience developing technologies for demanding operating environments,” said Honeywell Aerospace researcher Kevin Plocher. “The study offers a promising foundation for thermal-control solutions in systems where conductive metallic coatings are undesirable or impractical.”

 

About the Advanced Science Research Center at the CUNY Graduate Center

The Advanced Science Research Center at the CUNY Graduate Center elevates scientific research and education at CUNY and beyond through initiatives in environmental sciences, nanoscience, neuroscience, photonics, and structural biology. The center promotes collaboration among established scientists, early-career researchers, and students working across disciplines to address complex scientific questions and societal challenges.

About the CUNY Graduate Center

The CUNY Graduate Center is a leader in public graduate education devoted to enhancing the public good through pioneering research, serious learning, and reasoned debate. The Graduate Center offers ambitious students nearly 50 doctoral and master’s programs of the highest caliber, taught by top faculty from throughout CUNY, the nation’s largest urban public university. Through its nearly 40 centers, institutes, initiatives, and the Advanced Science Research Center, the Graduate Center influences public policy and discourse and shapes innovation.

---

Journal

Nature Communications

DOI

10.1038/s41467-026-74805-3 

Method of Research

Experimental study

Subject of Research

Not applicable

Article Title

Broadband Radiative Heat Transfer Suppression via Dispersion-Engineered Metasurfaces

 

Researchers identify the immune cells that keep a deadly fungus in check

A Virginia Tech study finds that control of Cryptococcus neoformans depends not on a single immune cell type, but on several working together — a discovery that could reshape how doctors think about preventing life-threatening fungal infections.

Virginia Tech

Facebook

XLinkedInWeChatBlueskyMessageWhatsAppEmail

 

image: 

(From left) Kirsten Nielsen, Ian Jeong, Priscilla Atim, and Rachel Ber-Murante in the Nielsen Lab. Kirsten Nielsen's research focuses on how the fungal infection cryptococcus shifts from a dormant infection to a harsh and dangerous one.

view more 

Credit: Photo by Andrew Mann for Virginia Tech.

Most people carry the fungus Cryptococcus neoformans in their lungs for life and never know it, held in check by the immune system. New research from the Virginia-Maryland College of Veterinary Medicine at Virginia Tech identifies which immune cells do that work — and finds that no single cell type is responsible.

The study, published in the journal mBio, focused on CD4 T cells, the immune system's coordinators. Researchers had long assumed one dominant cell type controlled the infection. Instead, they found several distinct CD4 T-cell populations, each contributing in its own way.

"Everybody assumed we had the queen that was going to be the single most powerful player," said senior author Kirsten Nielsen, professor of microbiology and immunology at the college's Center for One Health Research. "But it turns out it's not just one queen. Imagine playing chess with five queens."

The finding matters because Cyptococcus turns deadly when the immune system falters. In people undergoing chemotherapy, recovering from organ transplants, living with HIV, or taking immune-suppressing drugs, the dormant fungus can reactivate, spread to the brain, and cause meningitis. It kills more than 150,000 people worldwide each year and is the second-leading cause of death among people living with HIV, according to the CDC and World Health Organization.

Doctors currently cannot predict or prevent that reactivation, in part because it was unclear which immune cells were containing the fungus in the first place. Because no single cell type is responsible, the results suggest that any future preventive treatment will need to protect a coordinated network of immune cells rather than target one.

The work is the latest advance in a research program Nielsen has built over more than a decade, tracing to her insight that the outcome of infection is decided in the lungs — not the brain, where symptoms appear. Reproducing the quiet, lifelong lung infection in mouse models took years before her lab, first at the University of Minnesota and now at Virginia Tech, could begin asking which immune cells mattered.

The fungus is also a veterinary concern, infecting cats, dogs, and pet birds. Because animals mount similar immune responses, the findings are expected to inform both human and animal medicine — a connection central to the veterinary college's One Health mission.

"We've added another piece to the puzzle," Nielsen said. "The picture is starting to resolve, but we're still a long way from completing it." Her team has not yet determined how these T cells communicate with the front-line cells they direct — the next step in the work.

The study, "Paradoxical Th1 activation and CTLA-4 regulation is beneficial during latent cryptococcosis," was supported by the National Institutes of Health, with collaborators at Harvard University and the University of Illinois.

---

Journal

mBio

DOI

10.1128/mbio.01528-26 

Article Title

Paradoxical Th1 activation and CTLA-4 regulation is beneficial during latent cryptococcosis