From a luminaire data file to a collaborative system for healthy lighting environments
Many people may not know what an IES profile is.
But if you have ever worked with lighting design, luminaire selection, illuminance simulation, project verification, or even seen a designer simulate lighting in software, you have probably used it indirectly.
Simply put: An IES profile is like the “light distribution ID card” of a luminaire.
It records how a luminaire emits light: Where the light goes, how much light is emitted in different directions, what the beam distribution looks like, and how the luminaire performs in space.
When designers import this file into lighting design or spatial simulation software such as DIALux, AGi32, Relux, Kujiale, COOLUX, or other platforms, they can calculate: Illuminance, uniformity, glare risk, wall brightness, dark zones, and compliance with design requirements.
So although an IES profile may look like a small technical file, it is actually one of the lighting industry’s most important foundation languages.
Traditionally, it answers one question: How does this luminaire distribute light into space?
But in the era of healthy lighting, the real question is changing: What kind of light does a person actually receive in a specific space, at a specific time, while performing a specific activity?
That is where an upgraded IES profile becomes meaningful.
1. Traditional IES Profile Solves the Question: Where Does the Light Go?
Traditional IES profiles are extremely important.
Without them, designers would struggle to predict how a luminaire performs once installed in a real space.
They allow lighting design to move from experience-based judgment to calculated simulation.
例如：
Is a downlight narrow beam or wide beam?
Does a linear luminaire emit only downward light, or also side light?
Is an office luminaire evenly diffused, or is it bright in the center and weak at the edges?
Does a classroom, office, hotel lobby, or retail space meet illuminance requirements?
These questions depend on photometric data files such as IES profiles.
The core value of a traditional IES profile is: It allows the way a luminaire emits light to be read, simulated, and calculated by software.
But its limitation is also clear.
It mainly describes: How the luminaire emits light.
It does not fully describe: How people receive light.
2. In Healthy Lighting, Light Is Not Only on the Desk — It Enters the Eyes and the Body
In conventional lighting design, the most common calculation target has been: Horizontal illuminance.
In other words, how many lux are delivered to a desk, floor, or working plane.
This remains important for visual tasks.
But healthy lighting requires a broader question: Does the right light, with the right spectrum, intensity, direction, and timing, enter the human eye and provide the appropriate biological signal?
This is where EDI / DER becomes important.
简单来说：
EDI helps us understand the equivalent stimulus received by different biological light-response channels.
DER helps us understand how efficient a light source is in stimulating those channels compared with a reference source.
But healthy light cannot be reduced to one number.
In particular, melanopic EDI is useful for understanding circadian lighting, daytime alertness support, and lower nighttime biological disruption.
The same luminaire may produce very different human effects depending on: Space, position, viewing direction, time of day, activity, duration of exposure, and the person using the space.
Therefore, the next generation of profile should not contain only photometric data.
It should include:
EDI / DER
Spectral data
Spatial model
Eye-position model
Time model
Activity model
Human-factor model
Only then can healthy lighting move from a marketing claim to a system that can be designed, calculated, verified, and improved.
3. The Real Meaning of an Upgraded IES Profile: From Luminaire Data to Human Light Exposure Data
If a future upgraded IES profile can integrate EDI / DER, spatial models, and human-factor models, it will no longer be just a luminaire data file.
It will become a new foundation data structure for the industry.
A traditional profile says: How does this luminaire emit light?
An upgraded profile begins to ask: Can this luminaire, in this space, at this time, for this activity and this user, deliver the right light exposure?
This is a critical shift.
It means the core object of evaluation in lighting is moving: From luminaire performance, to spatial delivery, to actual human exposure.
This will redefine the roles of lighting designers, software companies, and measurement instrument companies.
4. For Lighting Designers: From Creating Beautiful Light to Delivering Verifiable Good Light
Lighting designers will be among the most important players in this transformation.
Traditionally, the value of an excellent lighting designer has been expressed through: Aesthetics, atmosphere, hierarchy, glare control, material expression, emotional tone, and compliance with illuminance levels.
These remain essential.
But in the future, the professional value of designers will be expanded.
Clients will increasingly ask:
Does this office truly support daytime focus?
Does this hotel room support nighttime relaxation?
Does this classroom provide sufficient daytime light exposure?
Does this senior-care environment support circadian stability?
Does this home reduce unnecessary biological stimulation before sleep?
These questions cannot be answered by aesthetics alone.
They cannot be answered by CCT alone.
Designers will need new tools to say: I am not only designing the visual effect of light. I am designing the quality of human light exposure.
New roles for designers
Future lighting designers may become:
Healthy lighting environment strategists
Human light exposure designers
Human-centric lighting consultants
Scene-based light recipe designers
Verification-oriented lighting system integrators
This expands the service boundary of lighting design.
New business value for designers
An upgraded IES profile may create new professional service opportunities:
Healthy lighting strategy consulting
EDI / DER simulation design
Circadian lighting scene design
Sleep-friendly residential lighting design
WELL / healthy building alignment services
Post-installation commissioning
Annual re-measurement and optimization services
This means designers are no longer only selling drawings or design schemes.
They can sell: Verifiable healthy lighting outcomes.
That is an important transition from aesthetic service to evidence-based professional service.
5. For Software Companies: From Illuminance Calculation Tools to Healthy Lighting Simulation Platforms
Software companies may be one of the biggest beneficiaries of this shift.
All new data models need software to carry them.
Traditional design software mainly calculates: Illuminance, uniformity, glare, light distribution, energy use, and basic scene effects.
But if an upgraded IES profile can include EDI / DER, spectrum, space, human factors, and time, software can evolve from a lighting calculation tool into: A healthy lighting environment simulation platform.
This is a major commercial upgrade.
New capabilities for software companies
EDI / DER simulation
Designers could directly see melanopic EDI at different seats, different eye positions, and different viewing directions.
Human-eye-view modeling
Instead of only simulating working planes, software could model seated eye height, standing eye height, elderly users, children, hospital beds, reading positions, and screen-work positions.
Time-based simulation
Healthy lighting is not a static rendering. It changes across morning, daytime, evening, nighttime, and late night. Software should simulate 24-hour light patterns, daylight plus electric light, automatic dimming strategies, pre-sleep low-disruption scenes, and shift-worker exposure strategies.
Activity-based simulation
A living room may support reading, watching TV, family interaction, evening relaxation, pre-sleep preparation, and morning activation. Software that connects activity models with light exposure will become far more valuable.
Verification loop
Future software should not stop at design-stage simulation. It should receive on-site measurement data and compare:
Design value vs measured value
Simulation value vs verification value
Initial condition vs operational condition
Ideal light environment vs actual light environment
This turns software from a design tool into a data platform for design, construction, verification, and operation.
New business value for software companies
This can create new revenue models:
Healthy lighting modules
EDI / DER calculation engines
WELL reporting and compliance tools
Human-factor simulation packages
Cloud-based light environment data services
Design–verification–operation platforms
API integration with sensors, controls, and measurement instruments
Software companies will no longer only sell design tools.
They may become the core data layer of healthy buildings and intelligent spaces.
6. For Measurement Instrument Companies: From Light Meters to Verification Infrastructure for Healthy Lighting
Measurement instrument companies will also face major opportunities.
If healthy lighting is to become verifiable, on-site measurement is essential.
Without measurement, there is no verification.
Without verification, there is no trust.
Without trust, there is no high-value healthy lighting market.
Traditionally, measurement instruments have focused on: Lux, CCT, CRI, chromaticity, flicker, spectrum, and luminous flux.
But the future question is not only whether a luminaire performs well. It is: Does the person in the space actually receive the right light?
New roles for measurement instrument companies
Measurement instrument companies may become:
Healthy lighting verification tool providers
On-site EDI / DER measurement gateways
Spatial light exposure data collectors
WELL / healthy building verification supporters
Field calibration partners for design software and control systems
Long-term monitoring sensor providers
This role is critical because all design models must eventually return to the real site.
New capabilities needed
Measure EDI / DER, not only lux
Instruments must calculate α-opic metrics, including melanopic EDI, from spectral data.
Measure spatial distribution, not only a single point
Healthy lighting requires data from different seats, eye positions, viewing directions, user postures, and time periods.
Measure accumulated exposure, not only an instant reading
Light has a time dimension. Too little daytime light and too much nighttime stimulation are both problems. Instruments and sensors should support exposure start time, accumulated exposure, daily light curves, 24-hour light environment records, and long-term operational stability.
Measure temporal light quality, not only spectrum
Flicker may be a luminaire problem, a control problem, a dimming problem, a spatial interaction problem, or a scene-transition problem. Future verification should consider spectrum, biological exposure, flicker risk, dimming stability, dynamic scenes, and long-term temporal quality.
New business value for measurement instrument companies
Practical opportunities may include:
Professional EDI / DER meters
WELL Light verification tools
Healthy residential lighting inspection kits
School / office / healthcare / senior-care testing packages
On-site commissioning tools for designers
Cloud-based report generation
Annual re-measurement and calibration services
Long-term monitoring modules connected to control systems
Healthy light inspection services for building owners
In the future, measurement instrument companies may not just sell devices.
They may sell: The trust infrastructure of healthy lighting.
7. A New Triangle: Designers, Software Companies, and Measurement Instrument Companies
In the traditional lighting industry, these three roles were relatively separate.
In the healthy lighting era, the three will become tightly connected.
A future closed-loop workflow may look like this:
Step 1: Designers define the healthy lighting strategy
For example: daytime activation, nighttime protection, sleep-friendly lighting, office performance, or circadian support for senior care.
Step 2: Software simulates EDI / DER + spatial + human-factor exposure
Design-stage prediction becomes more human-centered.
Step 3: Luminaires and control systems deliver targeted scenes
The system no longer delivers only power or illuminance, but targeted light exposure.
Step 4: Measurement instruments verify the real site
Measured EDI / DER, flicker, and spatial distribution confirm whether the design intent is achieved.
Step 5: Software compares measured values with design values
Models are calibrated, and deviations are corrected.
Step 6: Designers and building owners receive traceable reports
Healthy lighting becomes a verifiable deliverable, not just a promise.
Once this loop is established, healthy lighting gains a real foundation for industrialization.
8. The Biggest Business Shift: From Selling Products to Selling Verifiable Outcomes
The commercial meaning of an upgraded IES profile is clear: It allows the lighting industry to move from product price competition to outcome value competition.
In the past, the market often compared:
Who has the cheaper luminaire?
Who has higher efficacy?
Who has a better-looking product?
Who has more attractive specifications?
In the future, the market can compare:
Who can deliver better daytime light exposure?
Who can reduce nighttime biological disruption?
Who can make schools, offices, hotels, and senior-care environments more verifiable?
Who can provide a complete data chain from design to construction, verification, and operation?
This shifts lighting from hardware supply to light environment services.
9. Strategic Meaning for GLGA / LRS
This direction is highly aligned with what GLGA and LRS are working to promote.
Good Light Wake-up Call is not about slogans. It is a call for the industry to recognize that good light must be designed, calculated, verified, and continuously improved.
The EDI / DER Working Group should not only discuss new metrics. Its deeper value is to connect LED makers, luminaire companies, design software providers, control systems, measurement instruments, and standards organizations around a shared data language.
In. Licht Ultra / Pro / Well can play a role not only as tools, but as field verification gateways within this future data chain.
deLIGHTED Talk Asia / GILE 2026 can become an important platform to bring this topic to the Asian and global lighting ecosystem.
Because this is not the product agenda of a single company.
It is a foundation question for whether the healthy lighting industry can truly become real.
10. Conclusion: Not Just Upgrading a File, But Upgrading the Logic of the Industry
An IES profile was originally the light distribution ID card of a luminaire.
But if it begins to include EDI / DER, spatial models, and human-factor models, it may become: The foundation data language of healthy lighting environments.
This means the lighting industry is beginning to change its core question.
In the past, we asked:
Is this luminaire bright enough?
Is this space bright enough?
In the future, we must ask: Does this person, in this space, at this time, for this activity, receive the right light?
That is the real starting point of healthy lighting.
The next generation of lighting competition will not only be about brighter luminaires, higher efficacy, or better appearance.
It will be about who can build a complete capability:
Designed by professionals.
Simulated by software.
Delivered by products and systems.
Measured on site.
Calibrated through data.
Understood by building owners.
That is how healthy lighting moves from concept to industry.
The meaning of an upgraded IES profile is not that it adds another data field.
It means the lighting industry is finally moving from: Describing light, to understanding people, space, time, and the human experience of light.
Taiwan’s Next Opportunity in Human-centric Environmental Technology
By Lawrence Lin
Taiwan has long been one of the world’s most important technology manufacturing bases.
From semiconductors to displays, from LEDs to ICT, Taiwan built an extraordinary industrial ecosystem based on engineering excellence, manufacturing discipline, and supply-chain integration.
Behind much of this transformation, ITRI (Industrial Technology Research Institute) played a foundational role.
Over the past decades, ITRI not only advanced core technologies in optoelectronics, semiconductors, displays, and lighting, but also helped incubate or support the growth of some of Taiwan’s most influential technology companies, including:
TSMC
UMC
Epistar
Opto Tech
This history matters. Because Taiwan’s next opportunity may once again emerge from the intersection of technology, manufacturing, and societal transformation.
But this time, the opportunity may not simply be about chips, displays, or energy efficiency. It may be about something far more human: Light as environmental infrastructure for health, wellbeing, cognition, and quality of life.
The Industry Is Changing
For the past twenty years, the lighting industry largely competed on:
Efficiency
Cost
Reliability
Scale
But the next phase is fundamentally different. The central question is no longer only: “How efficiently can we generate light?”
The real question is becoming: “How should light interact with human biology, behavior, emotion, and time?”
This is where lighting converges with:
Neuroscience
Circadian biology
Healthcare
AIoT
Smart buildings
Environmental data science
And Taiwan is uniquely positioned to participate in this transition.
Taiwan Already Has the Foundations
Taiwan today possesses nearly all the key building blocks required for a future healthy-light ecosystem.
1. Strong Optoelectronics & LED Infrastructure
Taiwan has decades of experience in:
LED chips
Packaging
Drivers
Optical systems
Sensors
Displays
Micro LED
Embedded electronics
This remains a major strategic advantage.
2. World-class ICT & AIoT Capabilities
Healthy lighting is no longer just about luminaires. It increasingly depends on:
Sensors
Edge computing
Cloud platforms
AI-driven adaptation
Building integration
Long-term environmental monitoring
In many ways, healthy lighting is becoming a branch of: Environmental intelligence.
3. Healthcare & Aging Society Needs
Taiwan is entering a super-aged society. This creates growing demand for solutions related to:
Sleep quality
Cognitive performance
Mental wellbeing
Long-term care
Circadian support
Shift-work adaptation
Light is gradually evolving from a decorative or energy-saving product into: A health-supportive environmental system.
4. Scientific & Clinical Research Capability
Taiwan also possesses strong academic and medical research resources, including:
ITRI
Academia Sinica
National Taiwan University
Yang Ming Chiao Tung University
Major medical centers and hospitals
The challenge is not the lack of technology. The challenge is integration.
Taiwan’s Biggest Gap Is Not Technology
It Is a Shared Language
Today, much of the lighting industry still speaks in the language of:
CCT
比显指
Lux
Efficiency
Smart controls
But globally, the conversation is rapidly shifting toward:
melanopic EDI
alpha-opic metrics
circadian stimulus
temporal light
spatial light distribution
human response modeling
In other words: The industry is moving from “lighting products” toward “human environmental systems.”
This requires an entirely new interdisciplinary framework connecting:
Lighting
Architecture
Neuroscience
Healthcare
AI
IoT
Environmental psychology
And this is precisely where Taiwan has an opportunity to lead.
From Product Manufacturing to Human-centric Platforms
I believe Taiwan’s next strategic opportunity is not simply building better lamps.
It is building:
Verifiable Human-centric Environmental Platforms
This includes:
Measurement & Verification
Not only measuring lux, but also:
SPD
melanopic EDI
flicker
glare
spatial distribution
temporal exposure
biological light dose
Environmental Data Infrastructure
Building long-term datasets across:
Offices
Schools
Hospitals
Senior care
Residential spaces
Hospitality
Smart cities
Adaptive AI-driven Lighting Systems
Future lighting systems should not remain static.
They should:
Sense people
Understand context
Adapt dynamically
Learn continuously
Moving from: “Smart lighting” to: Adaptive human-centric environments.
The Opportunity for Taiwan
Taiwan once became globally important through:
PCs
Semiconductors
LEDs
Displays
The next opportunity may not simply be another hardware revolution. It may be:
Human-centric Environmental Technology
And light may become one of the most important — yet underestimated — foundations of this transition. Because humans spend nearly 90% of their lives indoors. And light remains the only environmental factor capable of directly influencing:
愿景
Circadian biology
Emotion
Alertness
Sleep
Human perception of time and space
Taiwan already has many of the required capabilities. The next step is no longer just manufacturing.
The next step is creating: A measurable, verifiable, adaptive, and human-centered environmental ecosystem.
This is also why organizations such as GLGA (Good Light Group Asia), together with global initiatives like the Good Light Wake-up Call, are trying to help build bridges between:
Science
Standards
Industry
设计
Healthcare
Architecture
Technology platforms
Because the future of lighting is no longer only about illumination. It is about understanding people.
Recently, Samsung Electronics announced that it would discontinue sales of certain consumer electronics products in mainland China.
Many headlines quickly framed this as: “Samsung exits China.”
But that interpretation is overly simplistic.
What Samsung is actually doing is far more important: It is transitioning from a “China-centered manufacturing model” toward a globally diversified supply-chain strategy.
And behind this decision lies a much bigger shift — one affecting not only Samsung, but also global manufacturing, consumer electronics, semiconductors, and even the lighting industry.
1. Is Samsung Really Leaving China?
Not really. Samsung is not withdrawing entirely from China.
What it is reducing or exiting includes:
Certain TV and home appliance sales businesses
Low-efficiency consumer electronics segments
Manufacturing models heavily dependent on China
But Samsung still maintains:
Smartphone and component sales in China
Semiconductor and memory operations
Its Xi’an NAND Flash facility
Partnerships with Chinese brands
Chinese supply-chain procurement networks
换句话说：
Samsung is not exiting China. It is exiting business models that no longer provide strategic competitiveness.
Those are two very different things.
2. What Samsung Is Really Abandoning
What Samsung is truly walking away from is:
The old foreign-brand advantage in China’s mature consumer electronics market
For nearly two decades:
Korean brands
Japanese brands
Western brands
benefited from:
Technological leadership
Brand premium
Quality perception
Global scale
inside China.
But China has fundamentally changed.
3. China Is No Longer an “Emerging Market”
It is now a hyper-competitive ecosystem. Samsung smartphones were once No.1 in China.
Then came:
Huawei
Xiaomi
OPPO
vivo
Honor
The issue was not that Samsung suddenly lost its technology edge.
The deeper issue was this:
Chinese companies became extraordinarily strong in supply chains, cost structure, distribution, speed, localization, and product iteration.
This was the turning point. China is no longer simply “the world’s factory.”
It has become:
A platform integrator
An ecosystem builder
A scenario creator
A global supply-chain organizer
And that is why many international brands — despite still having strong technologies — struggle to maintain leadership in China’s mainstream markets.
4. The Lighting Industry Has Already Experienced This
The lighting industry went through a very similar transition years ago.
Brands such as:
GE Lighting
OSRAM Lighting
PHILIPS Lighting
Zumtobel Lighting
Cooper Lighting
once held strong brand and technology advantages in China.
But Chinese lighting companies rapidly built strength in:
Manufacturing efficiency
Supply-chain density
ODM/OEM execution
Distribution penetration
Delivery speed
Engineering responsiveness
Meanwhile, companies like Signify (formerly Philips Lighting) chose to continue investing in China — but under a completely different competitive model.
Today, competition is no longer mainly about:
Efficacy
比显指
Brand
Instead, it is increasingly about:
System capability
Controls
Software integration
Data
AI
Human-centric applications
Spatial intelligence
5. A Personal Story About Samsung
I have always carried a deep impression of Samsung from one particular experience.
Years ago, during my collaboration with MLS, we were manufacturing lighting products for Samsung’s LED division. At that time, even before the first shipment was officially delivered, Samsung suddenly decided: To exit the finished lighting products business.
Internally, it was certainly a shock.
Because it meant:
Development costs
Supply-chain planning
Production schedules
Market preparation
all had to be restructured.
But what impressed me most was not the exit itself. It was the way Samsung handled it.
They did not:
Avoid responsibility
Delay communication
Push risks downstream to suppliers
Instead:
They communicated formally and responsibly with partners, purchased all completed products, and then—systematically destroyed them.
That experience left a deep impact on me. Because for the first time, I truly understood:
A global company can admit defeat, but still refuse to leave irresponsibly.
Many companies talk about “corporate culture.” But real corporate culture often becomes most visible during retreat, failure, or exit.
That experience taught me something I still remember today:
You can lose.
You can withdraw.
But you should never leave irresponsibly.
And I believe this is something many rapidly expanding companies today should seriously reflect upon.
6. Samsung’s Real Concern Is Not China
It is:
Geopolitics and supply-chain resilience
Samsung’s most critical businesses today are:
Semiconductors
AI memory
Advanced chips
Packaging technologies
Displays
All of which are deeply entangled in:
US–China technology competition
Semiconductor controls
AI infrastructure competition
Global supply-chain security
This is why Samsung has been:
Expanding Vietnam
Expanding India
Investing in the United States
Diversifying manufacturing footprints
This is not simply “de-Chinaization.”
It is: A strategy to build a more resilient global supply chain.
7. What Does This Mean for Taiwan?
For Taiwan, this trend is both a warning and an opportunity.
Warning
If companies continue relying mainly on:
OEM models
Manufacturing efficiency
Cost advantages
while lacking:
Platform capability
Standards leadership
System integration
AI and data capability
Scenario definition capability
they may eventually face the same structural pressure. This is already happening in LED and lighting.
Opportunity
At the same time, the world is increasingly searching for:
Supply chains outside China
High-trust technology partners
Higher-value integrated solutions
This creates opportunities for Taiwan in areas such as:
AIoT
Health technology
Sensing
Photonics integration
Smart controls
Precision manufacturing
Advanced semiconductors
Especially in the integration of: human factors + data + spatial intelligence
Taiwan still has enormous potential to differentiate itself.
8. What the Lighting Industry Should Really Learn
The biggest lesson Samsung offers the lighting industry is this:
The era of “just making lamps” is ending. The future value of lighting will not come only from hardware.
It will come from the ability to create lighting environments that are:
Verifiable
可測量
Adaptive
Continuously optimized
Competition is shifting from:
产品规格
toward:
Human-factor models
Spatial models
Sensors
AI
Data
Controls
Long-term operational validation
Because the market no longer simply needs spaces to be illuminated.
It needs light that genuinely supports: human biology, psychology, behavior, and wellbeing.
9. Final Thoughts: Samsung Is Not Leaving China — It Is Leaving an Era
If we reduce this story to: “Samsung failed in China,”
we miss the bigger picture.
What Samsung is really acknowledging is: The globalization model of the past 30 years is ending.
The old world optimized for:
Lowest cost
Centralized manufacturing
Maximum scale efficiency
The new world optimizes for:
Supply-chain resilience
Regional diversification
AI and data capability
System integration
Platform capability
Human-centric value creation
And this transformation is not happening only to Samsung.
It is happening across:
Semiconductors
Consumer electronics
Automotive
Buildings
Lighting
Health technology
and the entire global industrial landscape.
From that perspective:
Samsung is not exiting China.It is exiting the old era in which brand, scale, and globalization alone were enough to guarantee success.
In recent years, more and more terms that sound highly technical have emerged in the lighting industry: CAF, CS, EML, m-EDI, EDI, DER…
Many manufacturers, designers, consultants, and system providers have heard of them—and to some extent, used them. But if we push one step further and ask:
What exactly does each of these metrics describe?
Are they actually talking about the same thing?
Can they be used interchangeably?
The answers are often far less clear than people assume. This reflects a very typical situation in today’s lighting industry: There are more and more terms, but a true common language has not yet been established.
If the industry genuinely wants to move from simply “lighting up spaces” to accurately understanding how light affects people, then the first step is not to invent yet another new term.
It is to put these commonly used metrics back into their proper context.
Are these metrics really describing the same thing?
Let’s start with the conclusion: CAF, CS, EML, and EDI/DER are not different names within the same framework.
They originate from:
different stages
different objectives
different modeling approaches
Some function more like spectral efficacy ratios. Some behave more like physiological response models. Some are closer to application-level compromise metrics. And others are more like standardized, computable, and transferable baseline coordinates.
So the issue is not whether these terms should exist
The real issue is this: If the industry treats all of them as interchangeable “healthy lighting metrics,” confusion becomes inevitable.
But if each metric is placed back into its proper role, many of the current ambiguities start to resolve themselves.
Why is traditional lighting language no longer sufficient?
In the past, the most familiar language of lighting was built around:
illuminance
luminance
correlated color temperature (CCT)
color rendering (CRI)
light distribution
glare
These metrics are still essential. They primarily serve visual tasks and spatial quality:
Can we see clearly?
Is it comfortable?
Are colors accurate?
Is the space bright enough?
But the scope of lighting has expanded
A growing body of research now shows that light also affects:
circadian rhythms
alertness
emotional experience
even certain behaviors and physiological responses
Standards and position statements from the International Commission on Illumination have clearly indicated that: the traditional photopic system is not sufficient to fully describe human responses related to ipRGCs (intrinsically photosensitive retinal ganglion cells).
This changes the fundamental questions
The industry can no longer stop at asking:
“How many lux is this space?”
“Is it 3000K or 4000K?”
Instead, it needs to ask:
Which photoreceptive channels is this light stimulating?
What does this imply for vision, circadian regulation, and emotional response?
This is the real context behind new metrics
This shift is precisely why metrics like:
CAF
CS
EML
EDI / DER
have emerged.
They are not just “new terminology,” but attempts to extend lighting language from: visual description → human biological interaction
In other words: from “how the space looks” to “how light actually affects people.”
The human eye doesn’t just “see” — it also “feels” light.
In the lighting industry, the most commonly discussed elements are rods and cones. That’s not wrong.
Rods are mainly associated with low-light (scotopic) vision. Cones are responsible for color, detail, central vision, and typical daytime visual functions.
But today we know that, beyond rods and cones, there is another critically important photoreceptive pathway in the human eye: ipRGCs (intrinsically photosensitive retinal ganglion cells).
These are associated with melanopsin, are more sensitive to short wavelengths, and are closely related to non-visual responses such as circadian rhythms, pupil response, and alertness.
However, to be more precise, what truly needs to be considered is not three systems, but five classes of photoreceptor channels: S-cone, M-cone, L-cone, Rod, and Melanopsin / ipRGC.
What CIE S 026:2018 establishes is a standardized metrology framework based exactly on these five photoreceptors.
In other words, for the first time, the industry has a shared language that is not only about “what can be seen,” but about “how light stimulates the five types of receptors.”
This is a critical shift. Because it means the lighting industry is moving from “spatial output” to “human input.”
What do CAF, CS, and EML actually represent?
1. CAF: closer to a “spectral efficiency ratio” mindset
CAF (Circadian Action Factor) has long been used to compare the potential of different spectra to stimulate circadian-related responses.
Its core logic is straightforward: under the same visual lighting conditions, is this spectrum more biased toward “circadian effect” or “visual effect”?
So CAF is essentially a weighted efficiency ratio. It helps compare different SPDs under the same photopic lux to determine which produces stronger circadian-related stimulation.
This approach is not without value. Its advantages are simplicity, intuitiveness, and suitability for early-stage comparisons.
But it also has clear limitations:
First, it reflects spectral properties rather than actual human exposure dose.
Second, it does not inherently include time, spatial context, viewing direction, or actual eye exposure.
Third, it is not the primary shared language in current international standards.
So CAF helps you understand “how biased a spectrum is,” but it is not suitable as a complete coordinate for human response.
CAF is more like a spectral screening tool, not a full human-centric lighting language.
2. CS: closer to a “specific physiological response model”
CS (Circadian Stimulus) has also had significant influence in recent years, especially in North America. Its logic differs fundamentally from CAF.
Rather than being a simple ratio, CS attempts—through a circadian phototransduction model—to map spectral stimuli onto a response scale related to melatonin suppression.
UL’s DG 24480 also proposes design targets based on this type of framework. The strength of CS is that: It goes beyond saying “more or less biased,” and tries to quantify “how strong the circadian system stimulation is.”
But this is also where the challenge lies. Once a metric moves from “describing input” to “predicting response,” it inevitably introduces modeling assumptions:
What spectral sensitivity functions are used
How rod, cone, and melanopsin interactions are handled
How dose-response is defined
How exposure duration is treated
How pupil state, timing, and exposure history are incorporated
As a result, CS has been accompanied by considerable methodological debate.
So a fair summary would be: CS is important, but it is better suited as an application-layer or response-layer model, rather than a foundational common coordinate system for the entire industry.
3. EML: closer to a “transitional language for application”
EML (Equivalent Melanopic Lux) has been widely promoted in application contexts such as WELL.
Its key contribution is that it helped many people realize, for the first time: Not all lux are the same.
From a communication and adoption standpoint, EML has played a significant role. It translates complex spectral–receptor relationships into a format that is easier to understand and specify in project requirements.
However, from a stricter standardization perspective, EML is not the ideal end state. The industry has increasingly shifted toward melanopic EDI, and further toward the more comprehensive α-opic EDI / DER framework, because these align better with the standardized structure defined in CIE S 026 and enable consistent use across organizations and systems.
So in one sentence: EML is a bridge toward human-centric lighting—but not the most suitable final coordinate system.
Why are EDI / DER closer to a true coordinate system?
Because they resemble a system that can be recorded, compared, and transmitted—like a “spectrum.”
1. EDI: describing “equivalent stimulus dose”
EDI (Equivalent Daylight Illuminance) can be understood as: How much illuminance from standard daylight (D65) would be required to produce the same level of stimulation for a given photoreceptor?
This allows results from different spectra to be compared within a unified framework.
2. DER: describing “stimulation efficiency”
DER (Daylight Efficacy Ratio) can be understood as: How efficient a given light is, per unit of photopic illuminance, at stimulating a specific photoreceptor.
CIE TN 015:2023 clearly defines the relationship: melanopic EDI = illuminance × melanopic DER
Together, these two quantities are powerful:
EDI reflects the actual dose reaching the human body
DER reflects the intrinsic efficiency of the light spectrum
One is exposure-focused, the other is source-focused. This combination is exactly what manufacturers, designers, control systems, and simulation tools need.
Why move from single m-EDI toward a full EDI / DER framework?
This is not a rejection of melanopic metrics. In fact, many recent consensus recommendations are indeed centered on melanopic EDI.
For example, Brown et al. (2022) suggest indoor light exposure guidelines such as:
At least 250 lx during the day
Preferably below 10 lx in the evening
As close to 1 lx as possible at night
These are important. But looking further ahead: Humans do not respond to light through melanopsin alone.
Visual performance, color discrimination, adaptation, spatial perception, aspects of emotional experience, and more complex neural responses all involve the combined action of rods, S/M/L cones, and ipRGC pathways.
So if the industry aims to build a future-oriented human-centric lighting coordinate system, focusing only on m-EDI is not enough.
What we need is a more complete EDI / DER framework: Not just melanopic—but incorporating stimulation across all five photoreceptor classes into a unified language.
This does not mean every project must present all five values. It means: The foundational language of the industry should leave room for a complete human model.
From “selling light” to “describing humans”: the industry needs a new staff notation
I like to use an analogy: EDI / DER in human-centric lighting is like musical notation in music.
Musical notation is not the music itself, but it is the foundational language that allows music to be recorded, transmitted, reproduced, and collaboratively created.
EDI / DER is similar.
It is not sleep itself. Not emotion. Not comfort. Not spatial aesthetics.
But it provides a way to more precisely describe: What this light is doing to the five photoreceptive channels of the human body.
With such a coordinate system, many long-standing ambiguities in the industry can finally be addressed collaboratively:
LED manufacturers can provide more meaningful spectral data
Luminaire manufacturers can define products in terms of human impact
Control systems can move beyond brightness and CCT to modulating receptor stimulus
Simulation tools can evolve from illuminance-based to human-input-based modeling
Designers can move from “feels healthier” to “designing with coordinates”
Without such a system, the industry easily remains stuck in vague language:
More natural Closer to daylight More circadian-friendly More comfortable Healthier
These terms are not useless—but without an underlying framework, they struggle to become a shared language across organizations and product chains.
The real value of EDI / DER lies in this: For the first time, “how light affects humans” can be written down—like a score.
What does this mean for LEDs, luminaires, systems, and designers?
For LED and module manufacturers
Future competitive data cannot be limited to lm/W, CCT, and CRI.
SPD and α-opic / EDI / DER information will become increasingly critical.
For luminaire manufacturers
In the future, luminaires won’t just deliver lumens into space.
They will deliver specific receptor-stimulation structures to the human eye.
For control system manufacturers
Control strategies should no longer stop at “what time to switch to what CCT and what dimming level.”
A more advanced control objective should be: To achieve a target balance of stimulus dose and experience for a given time, space, task, and user group.
For designers
Human-centric lighting design will go beyond “cooler in the morning, warmer in the evening.”
It will require thinking in terms of:
Which photoreceptors this light primarily stimulates
What the actual dose at the eye level is
How to balance visual performance, circadian support, and emotional experience
How daylight, electric light, reflections, and viewing direction interact
Once designers start thinking this way, lighting design evolves from “placing fixtures” to “modulating human response.”
Final point: the industry doesn’t lack terms—it lacks the ability to read the “score”
CAF, CS, EML, EDI / DER… These terms often feel confusing not because they lack importance, but because they are frequently discussed at the same level.
In reality, they answer different questions:
CAF → more like a spectral efficiency ratio
CS → more like a specific physiological response model
EML → more like an application-layer transitional language
EDI / DER → closer to a standardized, computable, and transferable coordinate system
If the industry truly wants to move from “illuminating spaces” to “effectively influencing people,” the next step is not to invent yet another concept— but to learn how to read this system.
Illuminance tells us how bright it is. EDI / DER begins to tell us how light acts on humans. And that may well be the real starting point of the human-centric lighting era.
CTA
If your organization is exploring:
How to upgrade LED or luminaire data from traditional photometric parameters to a language closer to human-centric lighting
How to integrate EDI / DER into product definitions, control systems, or design simulations
How to establish lighting evaluation methods that address circadian rhythms, visual performance, and emotional experience
From Percent Flicker and Flicker Index to SVM, PstLM, and PAVM — rethinking the dynamic relationship between light and humans
For more than a decade, the LED lighting industry has commonly used the statement: “Our lights are flicker-free.”
But the real question is: What does “flicker-free” actually mean?
Is it because camera sensors cannot capture visible banding?
Is it because the human eye cannot perceive flicker?
Is it because Percent Flicker is low?
Is it because SVM is within limits?
Or because PstLM passes compliance thresholds?
From the perspective of healthy lighting, human-centric lighting, and age-inclusive environments, the issue is far more complex than this.
Flicker should more precisely be understood within the framework of Temporal Light Modulation (TLM). It is not a single phenomenon, nor can it be defined by a single metric.
More importantly, flicker is not only a property of the light source itself. It is: the dynamic light exposure experienced by a person in a specific space, at a specific time, performing a specific activity, under a specific physiological and psychological state.
This is why next-generation healthy lighting cannot be limited to discussions of spectrum, illuminance, correlated color temperature, or color rendering index, nor even melanopic EDI / DER alone.
We must also incorporate the temporal quality of light into the system-level understanding of lighting.
1| Flicker is not a single phenomenon, but a set of phenomena
In the lighting industry, all temporal variations in light output are often broadly referred to as “flicker.” However, strictly speaking, variations in light output over time can lead to different types of human perceptual and physiological responses.
At minimum, these can be categorized into three major visual phenomena:
1. Direct Flicker: visible flicker
This is the most intuitive form of flicker. It refers to situations where the human eye directly perceives light as flashing, pulsing, or fluctuating.
This typically occurs under conditions such as:
low frequency operation
high modulation depth
poor driver quality
unstable dimming behavior
It most commonly leads to:
visual discomfort
eye strain
attention disruption
headaches
adverse reactions in sensitive individuals
This layer is typically described using metrics such as Percent Flicker, Flicker Index, and PstLM / Mp.
This is not perceived as flicker in the light itself, but rather as temporal distortion of moving objects. For example:
fan blades appearing to stop or reverse
hand movements appearing discontinuous
rotating machinery appearing to change speed incorrectly
motion trajectories appearing segmented
This is not only a comfort issue. In environments such as industrial facilities, healthcare, sports, kitchens, and laboratories, it can become a safety risk.
This layer is primarily described using SVM（频闪可见度指标）.
This is a historically underestimated phenomenon. It typically occurs during rapid eye movements (saccades). Instead of fixating steadily on a light source, humans constantly move, scan, shift gaze, and change focus.
In such conditions, certain lighting systems—especially:
high-intensity point sources
linear LED luminaires
vehicle headlights
stage lighting
retail display lighting
may produce the perception of multiple separated light images or streaks. This is known as the Phantom Array Effect.
It is particularly common in:
high-brightness point sources
exposed LED systems
linear luminaires
automotive lighting
entertainment lighting
retail environments
outdoor nighttime lighting
high-contrast visual scenes
In the latest TLM framework, this effect is increasingly quantified using PAVM (Phantom Array Visibility Measure).
This leads to a critical realization: Humans are not static lux meters. Humans move, scan, turn, fatigue, and respond to light in individualized ways.
2 | What do common flicker metrics actually represent?
Let us break down the main indicators.
1. Percent Flicker (modulation depth)
Percent Flicker is the most intuitive metric. It describes the relative difference between the maximum and minimum light output within a cycle.
In simple terms: the deeper the fluctuation, the higher the Percent Flicker.
If light output drops close to zero during a cycle, Percent Flicker becomes high. If light output remains nearly constant, Percent Flicker is low.
Its advantages:
simple
intuitive
easy to interpret
However, its limitations are significant. It does not tell us:
frequency of modulation
waveform shape
whether it is sine wave or PWM
duty cycle characteristics
perceptual visibility
stroboscopic risk
phantom array potential
fatigue or headache risk
Therefore, Percent Flicker only answers: How deep is the fluctuation?
It does NOT answer: Is this fluctuation harmful or perceptible to humans?
These are fundamentally different questions.
2. Flicker Index
Flicker Index extends beyond Percent Flicker by considering the area under the waveform over time, relative to the average level.
This makes it more sensitive to:
waveform shape
duty cycle behavior
PWM characteristics
temporal distribution of light output
For example, two systems with identical Percent Flicker (e.g., 50%) may have very different perceptual impacts depending on whether the waveform is smooth (sine-like) or sharp (square-like).
Flicker Index can better capture these differences. However, it still does not represent full human response.
It does not incorporate:
frequency-dependent visual sensitivity
task-dependent perception
motion-based stroboscopic effects
eye-movement-related phantom array effects
individual sensitivity differences
long-term fatigue or neurological response
Thus, Flicker Index helps describe waveform quality, but cannot be directly equated with health risk.
3. Frequency
Frequency is a fundamental parameter in all TLM analysis.
It answers: How many times per second does the light fluctuate?
Measured in Hz. However, frequency alone is insufficient for risk assessment.
Because at the same frequency (e.g., 1,000 Hz):
low modulation depth may be harmless
high PWM modulation may still cause issues
stationary viewing may reduce perception
rapid scanning of bright sources may induce phantom array effects
sensitive individuals may react differently
Therefore, frequency must always be interpreted together with:
modulation depth
waveform type
duty cycle
dimming level
viewing condition
task type
population sensitivity
In other words: Frequency defines the time scale, but not the full human risk profile.
4. PstLM / Mp: direct flicker perception metrics
PstLM is used to describe short-term visible flicker perception (direct flicker).
It helps answer: Can a typical observer perceive flicker under given conditions?
In newer frameworks such as TM-39, Mp is also used for similar evaluation of direct flicker. Its key value is that it shifts analysis from purely physical waveform characteristics to human perception-based assessment.
However, it has limitations. It does not fully capture:
motion discontinuity perception
phantom array effects during eye movement
migraine triggering potential
long-duration fatigue effects
cognitive load impact
neurological responses (EEG/fMRI-level effects)
Thus, PstLM / Mp is essential for direct flicker assessment, but not sufficient as a complete human discomfort model.
5. SVM: stroboscopic visibility measure
SVM is designed to describe the visibility of stroboscopic effects.
It answers: Will moving objects appear discontinuous under this lighting?
It is critical in:
manufacturing
machining
rotating machinery environments
laboratories
kitchens
sports facilities
medical procedure areas
logistics and warehousing
fast hand-motion tasks
Its importance is not whether light flickers, but whether motion perception is distorted. In environments with rotating machinery, stroboscopic effects can lead to misinterpretation of equipment motion, creating safety hazards.
However, SVM is not a universal indicator. It does not fully predict:
phantom array effects
headaches or migraine triggers
long-term visual fatigue
neurological sensitivity responses
non-visual physiological effects
Therefore, SVM is a key metric for dynamic visual safety, but not a comprehensive “overall comfort score.”
6. PAVM: Phantom Array Visibility Measure
PAVM is a relatively recent and important development.
It corresponds to the Phantom Array Effect, which refers to the perception of multiple separated light images or streaks when the human eye moves—such as during saccades, scanning, or head rotation.
This type of effect has historically been underrecognized, largely because conventional testing assumes a stationary observer.
However, in real-world conditions, humans are never static. We constantly:
walk
turn our heads
scan environments
shift attention between near and far objects
move between screens and lighting environments
visually browse objects in retail spaces
observe exhibits while in motion
scan vehicle headlights at night
Therefore, PAVM addresses a critical gap in traditional flicker evaluation.
It is particularly relevant for assessing:
retail environments
exhibition and museum spaces
stage and entertainment lighting
high-brightness point sources
automotive lighting
linear luminaires
outdoor nighttime lighting
educational and medical environments
The emergence of PAVM highlights a fundamental shift: Flicker evaluation can no longer assume static viewing conditions. It must account for human motion, eye movement, and real behavioral patterns.
3 | Core differences between key metrics
We can summarize the relationships between the main indicators as follows:
Metrics
Main Description
Layer Classification
Main Purpose
Maximum Limitations
频闪百分比
Depth of light wave fluctuations
Description of physical stimuli
Fast judgment of modulation degree
Does not consider frequency and human body perception
频闪指数
Waveform area and duty cycle
Description of physical stimuli
Determine waveform quality
Not a human response model
Frequency
Speed of light fluctuations
Time parameters
Determine time scale
Cannot judge risk individually
PstLM / Mp
Directly visible flicker
Visual response model
Direct Flicker
Does not cover SE / PAE / physiological discomfort
SVM
Jumping sensation of moving objects
Visual response model
Stroboscopic Effect
Not suitable for representing overall health risk
PAVM
Images separated by eye movement
Visual response model
Phantom Array Effect
Still mainly a visual model
Therefore, we can draw a key conclusion:
Percent Flicker, Flicker Index, and Frequency describe the physical stimulus itself; PstLM / Mp, SVM, and PAVM describe different layers of visual response; but none of them alone can fully define human discomfort or neurological response.
4 | Why we cannot simply say “flicker-free”
The term “flicker-free” is fundamentally too vague.
When a product claims to be “flicker-free,” it should at minimum clarify:
Is Percent Flicker very low?
Is Flicker Index very low?
Does it comply with PstLM requirements?
Does it comply with SVM requirements?
Has PAVM been measured?
Was it tested at 100% output, or also at 10%, 20%, and 50% dimming levels?
Is this based on single-luminaire testing or full spatial system testing?
What dimming method is used—sine-wave, DC, PWM, or quasi-square waveform?
Were sensitive populations considered, such as children, elderly users, or individuals prone to migraines or neurological sensitivity?
If these questions are not addressed, then “flicker-free” is merely a marketing phrase.
A genuinely professional statement should instead specify: Under defined output levels, defined dimming conditions, and defined control methods, the luminaire exhibits the following values: Percent Flicker, Flicker Index, Frequency, PstLM / Mp, SVM, and PAVM.
Only then can performance be verified, compared, and meaningfully applied in healthy lighting design.
5 | Flicker must be understood within the framework of “human × space × time × activity”
One of the most common mistakes in healthy lighting is reducing complex human responses to a single metric.
In the past, lighting was simplified into 勒克斯. Later, it became CCT. Then 比显指. Today, many people reduce healthy lighting to melanopic EDI.
But real-world conditions are not that simple.
Human-centric lighting must return to four dimensions: human × space × time × activity
Flicker should be understood in the same way.
1. Human: different people have different sensitivity to flicker
Not everyone responds to light in the same way. Under identical lighting conditions, some people may experience no issues, while others may report glare, irritation, headaches, or fatigue.
Groups that require special attention include:
Children and adolescents
They spend long hours in classrooms, tutoring centers, study desks, and screen-based environments.
Flicker may not always be explicitly reported, but it can manifest as:
reduced attention
reading fatigue
visual discomfort
irritability
decreased learning efficiency
Classroom lighting should not be evaluated solely by illuminance levels. It must also consider whether light remains stable, especially under dimming conditions, and whether low TLM performance is maintained in real operation.
Office workers and sub-healthy populations
Many office workers already experience:
dry eyes
headaches
sleep disruption
neck and shoulder tension
reduced attention
visual fatigue
High temporal light modulation (TLM) in office environments may not be the sole cause, but it can act as an aggravating factor. This is particularly relevant in:
open-plan offices
smart lighting systems with adaptive dimming
sensor-based control systems
environments mixing multiple lighting brands and drivers
In such cases, system-level TLM management becomes essential.
Migraine-sensitive and neurologically sensitive individuals
These individuals may not only be sensitive to brightness, but also to:
flicker
high contrast
bright point sources
dynamic lighting changes
phantom array effects
visual noise
For them, lighting discomfort is often more pronounced and complex. Therefore, healthy lighting should not only be designed for the “average user,” but also for sensitive populations.
Elderly users
The issue for elderly populations is not simply “more light.” They generally require:
stable illumination
soft visual environments
low glare
low flicker
safe dynamic perception
non-disruptive nighttime lighting
In corridors, kitchens, staircases, bathrooms, and long-term care environments, both stroboscopic effects and phantom array effects can significantly impact safety and spatial perception.
Medical and long-term care populations
In healthcare environments, users are often in a vulnerable physiological and psychological state. They may experience:
poor sleep
anxiety
fatigue
pain
increased sensitivity to environmental stimuli
In such contexts, light is not just illumination—it is part of the recovery environment.
Therefore, in addition to illuminance, glare, and spectrum, TLM must also be considered as part of lighting design in hospitals, wards, nursing stations, and rehabilitation spaces.
2. Space: single-luminaire compliance does not guarantee system compliance
Many flicker evaluations remain at the single-luminaire level. However, in real environments, people are not exposed to one lamp—they experience:
multiple luminaires
multiple angles
multiple reflections
multiple control circuits
multiple drivers
multiple dimming states
multiple visual tasks
A single compliant luminaire does not guarantee a compliant space. For example:
phase differences between luminaires
beat frequency between different drivers
waveform inconsistencies across dimming groups
reflections amplifying high-brightness artifacts
differences between eye-level exposure and desk-level measurements
perceptual effects during walking or scanning (including PAE-related phenomena)
Therefore, future lighting acceptance testing should not rely solely on single-luminaire reports.
Instead, it should evaluate real spatial exposure, including:
user eye-level conditions
desktop plane conditions
wall and surface reflections
circulation paths
lighting scenes and modes
nighttime operation modes
multi-luminaire simultaneous operation
scene transitions
This marks the shift from “luminaire flicker” to “spatial TLM exposure.”
3. Time: flicker risk varies across operating conditions
Flicker should not be evaluated only at 100% output.
In practice, many LED systems exhibit their most problematic behavior under dimmed conditions, especially:
10% dimming
20% dimming
low-level nighttime modes
sensor-driven dimming systems
scene switching events
daylight harvesting adjustments
standby modes
emergency operation modes
low-duty-cycle PWM control
This is why healthy lighting products must provide TLM performance data across multiple dimming levels—not just full output conditions.
Time also includes human biological timing. Morning, daytime, evening, nighttime, and pre-sleep conditions all require different lighting strategies. Nighttime healthy lighting should not be defined only by “low blue light.”
It should also ensure:
low illuminance
low glare
low melanopic stimulation
low TLM
low visual stress
A truly sleep-friendly lighting environment is not just warm in color temperature—it is stable, low-stimulus, low-fluctuation, and low-disruption as a system.
4. Activity: different tasks require different flicker management
The same luminaire can present very different risk profiles depending on the activity. For example:
Reading
Key concerns:
direct flicker
eye fatigue
attention interference
long-term visual stability
Office work
Key concerns:
interaction between display and lighting TLM
long-duration visual load
stability under dimming conditions
risk of eye strain and headaches
Industrial environments
Key concerns:
rotating machinery
moving objects
stroboscopic effects
safety misperception risks
Healthcare environments
Key concerns:
precision tasks
patient sensitivity
long working hours and fatigue
nighttime lighting in care stations
Retail and exhibition spaces
Key concerns:
high-brightness point sources
rapid visual scanning
phantom array effects
balance between visual comfort and product presentation
Residential and hospitality environments
Key concerns:
emotional comfort
relaxation
sleep preparation
nighttime safety
low visual stimulation
Therefore, healthy lighting should not be defined as “one scenario = one metric set,” but rather as a system where different activities require different lighting recipes.
6 | The real meaning for all-age and sub-healthy populations
All-age healthy lighting is not about making light brighter or warmer.
Its real purpose is to address: the integrated lighting needs of different ages, physiological states, spaces, times, and activities.
Within this framework, flicker management represents the temporal quality of light. If we define lighting functions as:
illuminance → visibility (“can I see clearly?”)
CCT → visual atmosphere (“what does the light feel like?”)
CRI → color accuracy (“are colors rendered correctly?”)
EDI / DER → spectral biological stimulus (“how does the spectrum interact with physiology?”)
Then TLM management addresses something different: whether light is stable, non-disruptive, and temporally compatible with human perception and physiology.
This is especially important for sub-healthy populations.
Because sub-health is rarely a single condition—it is a cluster of chronic stress factors, 例如
poor sleep
eye fatigue
mental tension
headaches
anxiety
reduced attention
heightened environmental sensitivity
In such states, every environmental stimulus can become a load.
Flicker, glare, high-intensity point sources, incorrect color temperature, and excessive nighttime stimulation can all accumulate into physiological stress.
Therefore, future healthy lighting should not only aim to be “bright” or “visually appealing,” but should instead focus on: a measurable, manageable, and verifiable low-burden lighting environment.
7 | What product development should look like
Future healthy lighting products should not only specify:
power
luminous flux
color temperature
比显指
beam angle
UGR
They should also clearly provide:
频闪百分比
频闪指数
Frequency
PstLM / Mp
SVM
PAVM
waveform characteristics
duty cycle
dimming curve behavior
driver ripple characteristics
TLM performance at 100%, 50%, 20%, and 10% output levels
performance under different control protocols
Especially for products claiming:
健康照明
eye protection lighting
learning environments
sleep-friendly lighting
Full transparency of temporal behavior is essential. Because “flicker-free” is not a scientific endpoint.
A truly professional product should instead state: Under defined output conditions, control strategies, and application scenarios, the TLM-related risks are controlled within specified ranges.
8 | What lighting design practice should evolve into
Lighting design should not rely solely on illuminance calculations or photometric files.
A more complete data structure is required: Photometry + Spectrum + Alpha-opic + TLM Profile
A healthy lighting design dataset should include:
photometric distribution data
spectral power distribution (SPD)
EDI / DER metrics
CCT / Duv
CRI / TM-30
频闪百分比
频闪指数
Frequency
PstLM / Mp
SVM
PAVM
dimming states
control profiles
scene tags
Only with this level of integration can we begin to build a true digital twin of healthy lighting.
Not just simulating how bright a space is, but simulating: how a human actually experiences dynamic light exposure over time, across activities and spatial contexts.
9. How site acceptance testing should evolve
Commissioning should no longer be limited to single luminaires or desktop illuminance measurements.
Especially in schools, offices, healthcare facilities, long-term care environments, hotels, high-end residential projects, and industrial spaces, evaluation should progressively include:
single-luminaire TLM
multi-luminaire combined TLM
eye-level user exposure TLM
task plane TLM
surface reflection TLM
dimming-state TLM
nighttime-mode TLM
scene-transition TLM
PAE risk during movement and scanning
SVM risk under dynamic mechanical operation
This marks the transition from: “product compliance” → “spatial compliance”
It is a critical step in moving healthy lighting from concept to engineering verification.
The lighting industry has gone through several stages of evolution:
from “having light” → “enough brightness”
from “brightness” → “energy efficiency”
from “efficiency” → “light quality”
from “light quality” → “healthy lighting”
But today, healthy lighting cannot be reduced to isolated indicators. We cannot only talk about:
high CRI
low blue light
no flicker
high EDI
full spectrum
eye protection
sleep support
These are all meaningful, but incomplete. The next step is to return lighting to real human life:
What kind of person?
In what kind of space?
At what time?
Performing what activity?
In what physiological and psychological state?
Receiving what spectral, spatial, temporal, and dynamic light exposure?
This is the true foundation of human-centric lighting.
Conclusion: stop asking only “is there flicker?”
We should stop asking: Does this light have flicker?
And instead begin asking: Under what frequency, waveform, dimming condition, spatial configuration, task context, and population sensitivity does this system produce direct flicker, stroboscopic effects, phantom array effects, and potential visual or physiological discomfort?
This is not overcomplicating the problem. It is clarifying it. Because humans are not static instruments. Spaces are not single-luminaire test setups. Time is not an average value. And activities are not abstract scenarios.
True healthy lighting must shift from static parameters to dynamic exposure:
from spectrum → time
from single luminaire → spatial system
from average user → real human diversity
from product metrics → lived experience
This is the direction flicker research must evolve toward.
And it is the challenge that next-generation healthy lighting, all-age lighting environments, and sub-healthy-friendly spaces must address.
Lawrence Industry Observation
I believe the healthy lighting industry is approaching a major inflection point.
One group of companies will continue to rely on marketing language, 例如
flicker-free
eye-friendly
full-spectrum
low blue light
Another group will move into engineering language, including:
SPD
EDI
DER
PstLM
SVM
PAVM
dimming profiles
spatial exposure models
And one step further, the real leaders will operate in a human-centric language framework: human × space × time × activity × individual sensitivity
This is the direction I have consistently emphasized. Healthy lighting is not about optimizing a single metric in isolation.
It is about building a lighting environment system that is:
measurable
verifiable
manageable
continuously optimizable
Within this system, flicker management is not optional. It is a fundamental component.
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