{"id":1345,"date":"2026-07-07T09:18:09","date_gmt":"2026-07-07T09:18:09","guid":{"rendered":"https:\/\/goodlightgroupasia.org\/?p=1345"},"modified":"2026-07-08T02:20:49","modified_gmt":"2026-07-08T02:20:49","slug":"spatial-brightness-perception-healthy-lighting-cannot-be-evaluated-by-desktop-illuminance-alone","status":"publish","type":"post","link":"https:\/\/goodlightgroupasia.org\/zh\/spatial-brightness-perception-healthy-lighting-cannot-be-evaluated-by-desktop-illuminance-alone\/","title":{"rendered":"Spatial Brightness Perception: Healthy Lighting Cannot Be Evaluated by Desktop Illuminance Alone"},"content":{"rendered":"

deLIGHTed talks Asia @ GILE 2026<\/h3>\n\n\n\n

Good Light Wake-up Call Series Report 19<\/h3>\n\n\n\n
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Dai Qi \/ Fudan University: Redefining Healthy Lighting Evaluation Standards Through Spatial Brightness Perception<\/h2>\n\n\n\n

In the previous reports, we have explored the complete picture of healthy lighting from multiple perspectives through the Good Light Wake-up Call\uff5c\u597d\u5149\u89c9\u9192\u884c\u52a8<\/strong> series.<\/p>\n\n\n\n

Professor Robert Lucas<\/strong> explained why traditional lux is no longer sufficient to describe how light communicates time information to the human body. <\/p>\n\n\n\n

Dr. Marijke Gordijn<\/strong> reminded us that good light means delivering the right light to the body at the right time. <\/p>\n\n\n\n

Jan Denneman<\/strong> challenged the lighting industry to shift its focus from illumination toward human outcomes. <\/p>\n\n\n\n

Kei Haraguchi \/ \u539f\u53e3\u572d<\/strong> highlighted from the LED source perspective that, thirty years after the introduction of white LEDs, the industry\u2019s goal should no longer be limited to improving LPW (lumens per watt). <\/p>\n\n\n\n

Dr. Anne Berends<\/strong> expanded the discussion of healthy lighting into near-infrared light, dosage, and scientific boundaries. <\/p>\n\n\n\n

\u8d75\u5f18\u8f76\u4e3b\u4efb <\/strong>brought healthy lighting into healthcare environments. <\/p>\n\n\n\n

\u6797\u71d5\u4e39\u6559\u6388<\/strong> brought the conversation back to residential spaces. <\/p>\n\n\n\n

\u6797\u4f1f\u6770\u535a\u58eb<\/strong> explained how light influences the brain through visual pathways, brain states, and brain clearance mechanisms. <\/p>\n\n\n\n

\u90d1\u7ea2\u6210 <\/strong>used EEG research to remind us that without validation, there is no truly evidence-based healthy lighting. <\/p>\n\n\n\n

Zoe Xia<\/strong> from IWBI further showed that healthy lighting must evolve from health narratives into value evaluation.<\/p>\n\n\n\n

The presentation by \u6234\u5947<\/strong> returned to a question that appears fundamental, yet is critically important: Why do people perceive a space as \u201cbright\u201d or \u201cnot bright\u201d?<\/strong><\/p>\n\n\n\n

This is not simply a question of illuminance.<\/p>\n\n\n\n

In many cases, a high desktop illuminance level does not necessarily mean that a space feels bright. The same luminaire output does not always create the same perception of brightness. A space may provide sufficient light for visual tasks while still failing to deliver overall visual comfort<\/strong>. Meeting traditional lux requirements does not automatically mean that people\u2019s perception of brightness, comfort, and wellbeing has been addressed.<\/p>\n\n\n\n

\u6234\u5947<\/strong>\u2019s presentation, \u201cResearch on Spatial Brightness Evaluation Methods,\u201d<\/strong> focuses on this important topic.<\/p>\n\n\n\n

The core question of this report is one that the healthy lighting industry must confront: We cannot evaluate lighting only by measuring illuminance on the working plane. We must also understand the brightness that people actually perceive within a space.<\/strong><\/p>\n\n\n\n

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1 | What Is Spatial Brightness?<\/h2>\n\n\n\n

Spatial brightness <\/strong>refers to a person’s subjective perception of how bright an entire space feels. <\/p>\n\n\n\n

Unlike the traditional lighting metric of task illuminance, spatial brightness focuses on the overall visual impression of a room rather than the amount of light falling on a work surface<\/strong>.<\/p>\n\n\n\n

Task illuminance<\/strong> addresses questions such as whether a desk is bright enough, whether documents can be read clearly, whether the work surface meets lighting standards, and whether reading and writing tasks are adequately supported. These are, of course, important considerations. <\/p>\n\n\n\n

In traditional environments such as offices, classrooms, libraries, and other task-oriented settings, task illuminance has long been the primary design criterion because visual performance depends on sufficient light at the work surface.<\/p>\n\n\n\n

However, the way we use spaces has changed significantly. Today, our visual activities extend far beyond reading and writing on paper. We now spend much of our time interacting with self-luminous digital displays, participating in meetings and collaborative discussions, working in immersive office environments, and occupying residential living rooms, hotel guest rooms, hospital patient rooms, senior living and wellness facilities, museums, retail spaces, classrooms equipped with projectors and electronic displays, and open-plan offices where long-term visual comfort is essential.<\/p>\n\n\n\n

In these environments, people are not simply looking at a desk or a work surface\u2014they are experiencing the entire space. They instinctively judge whether a room feels bright or dim, open or confined, comfortable or oppressive, welcoming or uninviting. They also respond to whether the space provides a sense of safety, supports alertness, and encourages them to remain there. These perceptions are all closely related to spatial brightness.<\/p>\n\n\n\n

For this reason, healthy lighting design should not stop at asking, “What is the task illuminance on the work surface?” <\/strong>It should also ask, “How bright does the entire space feel to the people experiencing it?”<\/strong><\/p>\n\n\n\n

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2 | Why Isn’t Task Illuminance Enough to Explain How Bright a Space Feels?<\/h2>\n\n\n\n

\u6234\u5947\u6559\u6388<\/strong> presented a striking example in his presentation. Two lighting scenarios used luminaires with the same luminous flux output. Yet the scenario with the lower desk illuminance actually appeared brighter overall. This serves as an important reminder for the lighting industry.<\/p>\n\n\n\n

For many years, lighting design and project acceptance have relied heavily on horizontal illuminance<\/strong>. We are accustomed to discussing targets such as 300 lux, 500 lux, or 750 lux, confirming that desk illuminance meets the required standard and that the work plane complies with specifications. While these metrics remain important, they do not fully explain how bright a space feels to its occupants.<\/p>\n\n\n\n

Perceived spatial brightness<\/strong> is influenced by three factors working together. The first is light intensity<\/strong>\u2014how much light is present within the space. The second is the spectral composition of the light<\/strong>\u2014what kind of light is being emitted. The third is the spatial distribution of light<\/strong>\u2014where the light falls, whether the walls and ceiling are illuminated, whether vertical surfaces are bright, how much light reaches the eyes, and how brightness is distributed across both the central and peripheral visual field.<\/p>\n\n\n\n

This means that two spaces can have the same luminaire power, the same luminous flux, and even the same task illuminance, yet create completely different visual experiences. <\/strong>One room may have a brightly illuminated desk but dark surrounding walls, making the overall environment feel enclosed and oppressive. Another may have slightly lower desk illuminance but evenly illuminated walls and ceiling, creating a brighter, more open, and more comfortable atmosphere. <\/p>\n\n\n\n

A space may achieve high horizontal illuminance yet still produce glare or visual discomfort because of poor brightness distribution. Likewise, a room may fully comply with illuminance standards while occupants still perceive it as dim, stuffy, or uncomfortable.<\/p>\n\n\n\n

This is precisely why evaluating spatial brightness is so important. It shifts lighting design beyond the work plane and toward the way people actually perceive and experience the entire space.<\/p>\n\n\n\n

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3 | From Task Illuminance to Eye-Level Experience: The Language of Healthy Lighting Is Changing<\/h2>\n\n\n\n

The traditional emphasis on task illuminance has a solid historical foundation. For decades, most visual tasks took place on a work surface\u2014reading, writing, drafting, office work, inspection, and manufacturing. Ensuring adequate illuminance on the work plane was therefore the cornerstone of lighting engineering.<\/p>\n\n\n\n

Today, however, lighting evaluation is shifting from the work plane to the eye. Professor Robert Lucas<\/strong> has emphasized that circadian lighting should be assessed based on vertical light exposure at the eye. Likewise, the WELL Light concept<\/strong>, particularly Feature L03<\/strong>, highlights the importance of evaluating melanopic light intensity at eye level. In healthy homes, the discussion is no longer limited to desktop tasks but extends to 24-hour light exposure. Healthcare facilities, offices, hotels, schools, and senior living environments increasingly require an understanding of people’s actual visual and biological light exposure rather than simply the amount of light reaching a horizontal surface.<\/p>\n\n\n\n

\u6234\u5947\u6559\u6388<\/strong>‘s research on spatial brightness reflects the same evolution in thinking. Instead of asking only how much light reaches the desktop, it asks how light is distributed throughout the space, how it enters the occupant’s field of view, how it shapes the perception of overall brightness, and whether it aligns with the way people naturally experience their environment. This perspective closely parallels the broader direction of healthy lighting.<\/p>\n\n\n\n

Healthy lighting<\/strong> is no longer about measuring luminaires alone, nor is it simply about measuring the illuminance on a work surface. It is about understanding people’s real-world light exposure and their genuine experience of the spaces they occupy.<\/strong><\/p>\n\n\n\n

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4 | Earlier Metrics for Spatial Brightness: Valuable, but Not Easy to Apply<\/h2>\n\n\n\n

Spatial brightness is not a new concept<\/strong>. In his presentation, \u6234\u5947\u6559\u6388<\/strong> reviewed several earlier metrics and research approaches that have been developed to evaluate how bright a space feels. These include Mean Room Surface Exitance (MRSE)<\/strong>, which measures the average luminous exitance of room surfaces, Lav,B40<\/strong>, which represents the average luminance within a 40-degree horizontal band of the visual field, as well as other methods based on luminance distribution across the field of view.<\/p>\n\n\n\n

These metrics have made important contributions to lighting research. Together, they demonstrate that perceived spatial brightness cannot be explained by task illuminance alone. The brightness of room surfaces, the distribution of luminance within the visual field, and the overall luminous environment all play significant roles in shaping people’s subjective perception of a space.<\/p>\n\n\n\n

However, these approaches also present practical challenges. Many require complex measurements, making on-site implementation difficult. They often depend on luminance cameras or sophisticated computational methods that are not easily adopted in routine lighting design. In addition, their relationship with subjective human perception continues to require further validation, and different metrics vary in how they account for the contributions of direct and indirect lighting. These are challenges shared by many healthy lighting metrics.<\/p>\n\n\n\n

A metric that exists only in academic literature but is difficult to apply in practice is unlikely to transform the industry. Likewise, a scientifically rigorous metric that designers, engineers, and commissioning professionals cannot measure efficiently is unlikely to become part of everyday project delivery.<\/p>\n\n\n\n

For this reason, the future of spatial brightness research is not simply about developing increasingly sophisticated models. The real objective is to establish evaluation methods that are both scientifically robust and practical enough to be used confidently in real-world lighting design and project implementation.<\/p>\n\n\n\n

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5 | Why Is Indirect Corneal Illuminance (Ecor,i) Important?<\/h2>\n\n\n\n

\u6234\u5947\u6559\u6388<\/strong>‘s research team has introduced a highly promising metric known as indirect corneal illuminance (Ecor,i)<\/strong>. Its primary significance lies in providing a more practical way to quantify perceived spatial brightness.<\/p>\n\n\n\n

Compared with metrics such as Mean Room Surface Exitance (MRSE)<\/strong> and Lav,B40<\/strong>, Ecor,i <\/strong>offers several important advantages. It demonstrates a stronger correlation with people’s subjective perception of spatial brightness, is much easier to measure in real-world settings, and more accurately reflects how different lighting distributions influence the way occupants perceive the brightness of a space. Rather than relying on average characteristics of the room itself, Ecor,i <\/strong>moves the assessment closer to what the human eye actually receives.<\/p>\n\n\n\n

The presentation showed that across a variety of lighting distribution scenarios, Ecor,i <\/strong>exhibited better agreement with subjective ratings of spatial brightness than either MRSE<\/strong> or Lav,B40<\/strong>. This is particularly significant for lighting designers. If a metric more closely reflects human perception, can be measured efficiently on site, facilitates comparisons between design options, and integrates easily into both design and verification workflows, it has the potential to become a practical tool for everyday use rather than remaining an academic concept.<\/p>\n\n\n\n

This is exactly the type of metric the healthy lighting industry needs.<\/strong> It is neither based solely on subjective impressions nor so technically complex that it becomes impractical. Instead, it provides a meaningful link between people’s lived visual experience and measurable lighting parameters.<\/p>\n\n\n\n

The significance of Ecor,i<\/strong> extends beyond introducing another technical term. It represents an important shift in healthy lighting evaluation\u2014from assessing the average characteristics of a space to evaluating the light that actually reaches the occupant’s eyes.<\/p>\n\n\n\n

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6 | Spatial Brightness Is Influenced Not Only by Light Distribution, but Also by Spectrum<\/h2>\n\n\n\n

Another key aspect of \u6234\u5947\u6559\u6388<\/strong>‘s research is the influence of spectral composition on perceived spatial brightness. This is something most people intuitively recognize in everyday life. Under the same illuminance, warm white lighting often appears softer or dimmer, while cool white lighting tends to make a space feel brighter. A room illuminated at 3000 K, 4000 K, or 6500 K can produce distinctly different impressions of brightness, even when the measured illuminance remains the same.<\/p>\n\n\n\n

The challenge is that these differences cannot be fully explained by traditional photometry. Conventional photometric measurements are based primarily on the photopic luminous efficiency function, V(\u03bb)<\/strong>, which describes the spectral sensitivity of the human eye under daylight vision. While V(\u03bb) <\/strong>provides the foundation for measuring illuminance, it may not fully account for how people perceive the overall brightness of a space.<\/p>\n\n\n\n

Research suggests that S-cones<\/strong>, the short-wavelength-sensitive cone photoreceptors, may contribute to the perception of spatial brightness. Even more intriguingly, intrinsically photosensitive retinal ganglion cells (ipRGCs)<\/strong>\u2014which have traditionally been associated with non-visual responses to light\u2014may also play a role in how bright a space appears.<\/p>\n\n\n\n

This finding is particularly significant. Historically, ipRGCs<\/strong> have been discussed primarily in relation to circadian entrainment, melatonin regulation, alertness, and other non-image-forming effects of light. If these photoreceptors also contribute to perceived spatial brightness, the distinction between visual and non-visual responses to light becomes far more interconnected than previously assumed. It also helps explain why two lighting systems with identical photopic illuminance can create noticeably different perceptions of brightness when their spectral power distributions differ.<\/p>\n\n\n\n

For healthy lighting design, this means that illuminance alone is no longer sufficient, nor is correlated color temperature by itself. Designers must also consider the spectral composition of light and the contributions of multiple photoreceptor pathways to the human perception of spatial brightness.<\/p>\n\n\n\n

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7. m\/p Ratio and Spatial Brightness: Why Higher Melanopic Spectra May Appear Brighter<\/h2>\n\n\n\n

\u6234\u5947\u6559\u6388<\/strong>‘s research team conducted a series of highly controlled experiments using a multi-channel LED lighting system capable of precisely adjusting spectral power distribution. To isolate the effect of melanopic stimulation, they held multiple variables constant, including chromaticity, photopic illuminance, S-cone equivalent illuminance, and TM-30 Rg, while maintaining color rendering within a defined range. They then selectively varied the melanopic equivalent daylight illuminance (melanopic EDI)<\/strong> associated with ipRGC<\/strong> stimulation. In other words, the study was designed to minimize the influence of other factors so that the specific contribution of melanopic content to perceived spatial brightness could be examined.<\/p>\n\n\n\n

The results were compelling. To achieve the same perceived spatial brightness, light spectra with a higher melanopic-to-photopic ratio (m\/p ratio)<\/strong> required a lower matching photopic illuminance<\/strong>. In practical terms, this means that a spectrum with greater melanopic content may produce the same impression of brightness while requiring fewer photopic lux. The findings indicate that melanopic stimulation associated with ipRGC activation makes a measurable and positive contribution to the perception of spatial brightness.<\/p>\n\n\n\n

This has important implications for the healthy lighting industry. Until now, discussions of melanopic light have focused primarily on its role in circadian regulation and biological stimulation. \u6234\u5947\u6559\u6388<\/strong>‘s findings introduce another important perspective: melanopic content may influence not only non-visual biological responses but also how bright a space appears to its occupants.<\/p>\n\n\n\n

This opens the possibility of a new approach to lighting design. Instead of optimizing only for visual illuminance or circadian effectiveness, future lighting systems may be designed to simultaneously consider visual performance, biological impact, and perceived spatial brightness. Such an approach could enable designers to achieve a better balance among energy efficiency, visual comfort, human health, and the subjective experience of space.<\/p>\n\n\n\n

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8 | This Is Not About Simply Increasing Blue Light\u2014It Calls for More Sophisticated Spectral Design<\/h2>\n\n\n\n

It is important to define the scientific boundaries of these findings. If a higher m\/p ratio<\/strong> can enhance perceived spatial brightness, does that mean we should simply increase blue light? The answer is clearly no. Healthy lighting should never be reduced to the idea that “more blue is better.”<\/p>\n\n\n\n

Spectral design must simultaneously account for multiple factors, including the time of day, application, user population, visual task, age, visual comfort, circadian requirements, glare risk, sleep protection, color rendering quality, photobiological safety, and the long-term experience of occupants.<\/p>\n\n\n\n

During the daytime, a spectrum with greater melanopic content may help enhance both perceived spatial brightness and circadian stimulation. At night, however, excessive melanopic stimulation may interfere with healthy circadian rhythms and disrupt sleep. The lighting strategy appropriate for an office is not the same as that for a bedroom. Classrooms require different solutions from hotel guest rooms, just as hospital patient rooms differ from retail environments. Likewise, children, older adults, shift workers, and individuals with sleep disorders should not all be served by the same spectral design strategy.<\/p>\n\n\n\n

For this reason, Professor<\/strong> Dai Qi’s<\/strong> research should not be interpreted as encouraging the lighting industry to simply increase short-wavelength light. Its real contribution is to demonstrate that spectral composition is an important design variable, that perceived spatial brightness can be quantified more scientifically, and that the role of melanopic stimulation should be understood rather than reduced to simplistic labels. Healthy lighting requires a more refined balance between visual perception, circadian effects, and the specific needs of each application.<\/p>\n\n\n\n

This philosophy is fully aligned with the core message of the Good Light Wake-up Call\uff5c\u597d\u5149\u89c9\u9192\u884c\u52a8<\/strong> initiative: scientific research should not be oversimplified into marketing claims. Instead, it should be translated into design principles that are measurable, verifiable, and applicable in real-world lighting practice.<\/p>\n\n\n\n

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9 | What Does Spatial Brightness Mean for Schools, Offices, and Healthy Buildings?<\/h2>\n\n\n\n

Research on spatial brightness has significant implications for real-world lighting projects across a wide range of building types.<\/p>\n\n\n\n

The first is education. <\/strong>Classroom lighting has traditionally focused on achieving adequate desk illuminance, and this remains an essential requirement. However, today’s classrooms are no longer spaces dedicated solely to reading and writing. Students spend much of their time looking at whiteboards, digital displays, teachers, classmates, and the classroom environment as a whole. Even if desk illuminance meets the required standard, a classroom can still feel dark or oppressive if the overall space lacks brightness. Walls, ceilings, and vertical surfaces that are insufficiently illuminated can diminish the quality of the visual environment. Conversely, simply increasing horizontal illuminance may introduce glare and visual fatigue rather than improving the learning experience.<\/p>\n\n\n\n

For this reason, future classroom lighting should not be evaluated solely on desk illuminance. It should also consider perceived spatial brightness, vertical surface luminance, eye-level light exposure, spectral composition, and support for healthy circadian rhythms.<\/p>\n\n\n\n

The second application is the modern office. <\/strong>As digital displays have become the primary work interface, task illuminance alone no longer defines visual performance. Office environments increasingly depend on overall visual comfort, a strong sense of spatial brightness, and lighting that supports alertness during the day. If an office is designed to minimize energy consumption by reducing the overall brightness of the space, occupants may still experience fatigue, reduced mood, and a reluctance to remain in the environment, even when task illuminance technically complies with standards.<\/p>\n\n\n\n

The third application is healthy buildings.<\/strong> Healthy building design extends beyond energy efficiency and visual task performance. It focuses on people’s long-term experience of the built environment, including comfort, circadian health, emotional well-being, and overall performance. Spatial brightness provides an important bridge between visual perception and these broader health outcomes.<\/p>\n\n\n\n

It helps building owners and decision-makers understand why two spaces with the same measured illuminance can feel completely different to occupants. It demonstrates why high-quality lighting is not simply a matter of meeting illuminance targets, and why wall brightness, ceiling illumination, light distribution, and spectral composition all contribute to the value of a healthy indoor environment. It also reinforces that on-site lighting verification should extend beyond measuring desktop lux alone.<\/p>\n\n\n\n

This is the true industry value of spatial brightness. It shifts the focus of lighting evaluation from compliance with technical metrics toward creating spaces that people genuinely perceive as brighter, more comfortable, and more supportive of health and well-being.<\/p>\n\n\n\n

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10 | A New Perspective for Lighting Designers: Good Lighting Is Not About Illuminating the Desk\u2014It’s About Illuminating the Space Correctly<\/h2>\n\n\n\n

Professor Dai Qi’s<\/strong> research offers a clear message for lighting designers: good lighting is not achieved simply by illuminating the desktop. Good lighting is achieved by illuminating the space in the right way.<\/p>\n\n\n\n

This means designers should pay closer attention to where light is distributed throughout the environment, which surfaces are illuminated, whether walls contribute to the perception of brightness, whether ceilings are unnecessarily dark, whether brightness is balanced between the central and peripheral visual field, how much light actually reaches the occupants’ eyes, whether indirect lighting enhances spatial comfort, whether direct lighting introduces glare, how spectral composition influences perceived brightness, and whether correlated color temperature and the m\/p ratio<\/strong> are appropriate for the intended application.<\/p>\n\n\n\n

This represents a fundamental shift from the traditional approach of designing primarily to meet illuminance targets. Conventional lighting design often focuses on the number of luminaires, lamp power, fixture spacing, desk illuminance, uniformity, and compliance with standards. The concept of spatial brightness encourages designers to ask a different question: How do people actually experience the space?<\/strong><\/p>\n\n\n\n

That is precisely the transformation required for healthy lighting design.<\/p>\n\n\n\n

The focus moves from engineering compliance to human perception; from the horizontal work plane to the occupant’s eye level and the surrounding space; from luminaire placement to shaping the luminous environment; and from calculating illuminance to validating how people truly perceive and experience light.<\/p>\n\n\n\n

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11 | A New Perspective for Manufacturers: Future Product Competitiveness Will Depend Not Only on Efficacy, but Also on Spatial Contribution<\/h2>\n\n\n\n

Research on spatial brightness also carries important implications for LED and luminaire manufacturers. Traditionally, product development has focused on metrics such as luminous efficacy, power consumption, service life, color rendering, cost, optical distribution, dimming capability, and product certification. These factors will continue to be essential.<\/p>\n\n\n\n

However, as healthy lighting becomes increasingly integrated into project delivery, manufacturers will need to answer a broader set of questions. How does a luminaire contribute to perceived spatial brightness? Does it simply deliver light to the work surface, or does it enhance the brightness of the space as a whole? Does its optical distribution effectively illuminate walls and ceilings? Can it improve spatial comfort through indirect lighting? Does its spectral power distribution provide greater perceived brightness and stronger circadian support during the day? Can it reduce unnecessary melanopic stimulation in the evening? Does it provide designers with the spectral, optical, and human-centric performance data needed to make informed design decisions?<\/p>\n\n\n\n

In other words, a luminaire should no longer be viewed simply as a light-emitting device. It should be understood as a tool for shaping the perceived brightness and quality of an entire space.<\/p>\n\n\n\n

The next generation of high-value lighting products will not compete on lumens per watt (lm\/W)<\/strong> alone. They will also be evaluated by how effectively they shape the luminous environment, support human perception and well-being, help designers achieve healthy lighting objectives, provide measurable and verifiable performance data, and create differentiated value across different applications.<\/p>\n\n\n\n

This represents a fundamental shift\u2014from evaluating product performance in isolation to evaluating a product’s contribution to the experience and quality of the space it illuminates.<\/p>\n\n\n\n

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12 | A Message for China’s Lighting Industry: Move Beyond Illuminance and Price\u2014Compete on Perceived Value<\/h2>\n\n\n\n

China’s lighting industry has become exceptionally good at producing products that are brighter, more affordable, and faster to deliver. These strengths have driven remarkable growth over the past decades. However, if competition continues to focus primarily on price and technical specifications, it will be difficult for the industry to move up the value chain. Research on spatial brightness offers a new direction: shifting competition from illuminance alone to the value of human perception.<\/p>\n\n\n\n

In the past, the key questions were often straightforward: Which product delivers higher luminous efficacy at the same price? Which luminaire provides greater illuminance at the same power? Which supplier offers the lowest project cost? <\/p>\n\n\n\n

As healthy lighting becomes more widely adopted, these questions should evolve. <\/p>\n\n\n\n

Designers, owners, and developers should also ask: Which solution creates a brighter and more comfortable space? Which lighting distribution enhances the perception of openness without increasing energy use? Which design minimizes glare while improving visual comfort? Which spectral composition enhances daytime spatial brightness? Which solution provides measurable and verifiable evidence of spatial brightness performance? And ultimately, which solution enables building owners to recognize that they are not simply paying more for lighting, but investing in a higher-quality indoor environment?<\/p>\n\n\n\n

These questions are increasingly important for China’s lighting industry.<\/p>\n\n\n\n

If Chinese manufacturers compete only on production cost, it will be difficult to establish lasting leadership in the healthy lighting market. However, by combining advanced manufacturing capabilities with expertise in spectral engineering, optical distribution, on-site measurement, spatial brightness evaluation, and the evolving requirements of healthy buildings, they have the opportunity to move beyond selling luminaires and toward delivering the value of the luminous environment itself.<\/p>\n\n\n\n

That is the true direction of the healthy lighting industry’s next stage of development\u2014from selling lighting products to creating measurable, verifiable, and human-centered spatial lighting value.<\/p>\n\n\n\n

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13 | How Spatial Brightness Aligns with the Good Light Wake-up Call Initiative<\/h2>\n\n\n\n

The Good Light Wake-up Call\uff5c\u597d\u5149\u89c9\u9192\u884c\u52a8<\/strong> initiative has consistently promoted a clear vision for healthy lighting: it must move beyond concepts and become something that can be designed, measured, verified, and delivered<\/strong>.<\/p>\n\n\n\n

Professor Dai Qi’s<\/strong> research on spatial brightness provides a critical piece of that vision by addressing one fundamental question: How can our perception of a space be quantified?<\/strong><\/p>\n\n\n\n

Professor Robert Lucas<\/strong> helped us understand how light communicates time to the human body. Dr.<\/strong> Marijke Gordijn<\/strong> emphasized that good lighting must respect human circadian rhythms. Zoe Xia<\/strong> and the International WELL Building Institute (IWBI)<\/strong> demonstrated that healthy lighting must be clearly defined, measurable, and verifiable. \u90d1\u7ea2\u6210<\/strong> and \u6797\u4f1f\u6770\u535a\u58eb<\/strong><\/strong> showed how the effects of light on the brain and brain states can be objectively evaluated.<\/p>\n\n\n\n

\u6234\u5947\u6559\u6388<\/strong> reminds us of an equally fundamental question that should not be overlooked before we discuss circadian biology, neuroscience, or the broader value of healthy lighting: Do people actually perceive the space as bright, comfortable, and pleasant to occupy?<\/strong><\/p>\n\n\n\n

Spatial brightness provides the essential bridge between visual perception and the practical delivery of healthy lighting.<\/strong> It is neither a traditional measure of task illuminance nor merely a subjective impression. Instead, it seeks to translate the human experience of spatial brightness into parameters that can be compared, measured, designed, and verified.<\/p>\n\n\n\n

This is exactly the kind of tool the healthy lighting industry needs. It helps transform human perception from an abstract concept into an evidence-based design objective, allowing lighting professionals to create environments that are not only technically compliant but also genuinely supportive of human experience, health, and well-being.<\/p>\n\n\n\n

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Conclusion: Healthy Lighting Should Illuminate Not Only the Task, but Also the Experience of Space<\/h2>\n\n\n\n

Professor<\/strong> Dai Qi’s<\/strong> presentation brought an essential perspective to the Good Light Wake-up Call\uff5c\u597d\u5149\u89c9\u9192\u884c\u52a8<\/strong> at deLIGHTed Talks Asia @ GILE 2026<\/strong>. Healthy lighting cannot be evaluated solely by desk illuminance, luminaire luminous flux, traditional lux measurements, circadian metrics, or subjective impressions alone. Instead, it must also account for how people perceive the overall brightness of the spaces they occupy.<\/p>\n\n\n\n

Achieving this requires a more comprehensive understanding of light. Designers must consider not only light intensity, but also spectral composition, light distribution, eye-level exposure, the brightness of walls and ceilings, the luminance structure across the visual field, the m\/p ratio<\/strong>, the intended function of the space, the time of day it is used, and the way occupants subjectively experience the environment.<\/p>\n\n\n\n

Research on spatial brightness reminds us that the same luminaire luminous flux can create very different spatial experiences. The same desk illuminance does not necessarily produce the same perception of brightness. The same photopic lux can result in different impressions of a space when the spectral power distribution changes. A spectrum with greater melanopic content may enhance perceived spatial brightness during the daytime, while thoughtful light distribution may improve the quality of a space more effectively than simply increasing illuminance.<\/p>\n\n\n\n

This is the deeper principle behind healthy lighting design. The goal is not to make lighting brighter, but to make it more appropriate.<\/p>\n\n\n\n

The evolution of healthy lighting is a progression from task illuminance to spatial brightness, from horizontal-plane metrics to eye-level experience, from luminaire specifications to the quality of the luminous environment, from visual compliance to healthy lighting, and from subjective impressions to measurable, evidence-based evaluation.<\/p>\n\n\n\n

The healthy lighting of the future must do more than illuminate visual tasks. It must also illuminate the human experience of space. It must satisfy technical standards while responding to the way people genuinely perceive and inhabit their environments. It must be thoughtfully designed, objectively measured, and scientifically verified.<\/p>\n\n\n\n

That is the enduring message \u6234\u5947\u6559\u6388<\/strong> brought to the Good Light Wake-up Call\uff5c\u597d\u5149\u89c9\u9192\u884c\u52a8<\/strong>.<\/p>\n\n\n\n

Good Light Wake-up Call.\n\u597d\u5149\u89c9\u9192\u3002<\/strong><\/p>\n\n\n\n

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\"\"<\/figure>","protected":false},"excerpt":{"rendered":"

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