• Light and Health Are Not Pseudoscience: What Two Nobel Prizes Tell Us About the Next Step in Lighting Research

    Oktober 8, 2026

    By Lawrence Lin
    Chairman, GLGA | Board Member, GLG | IWBI WELL Light Concept Advisor | Founder & CEO, LRS

    Today, while attending the Good Light Group (GLG) board meeting, I asked the directors—particularly our Chief Scientist, Marijke—about the significance of the newly announced Nobel Prize in Physiology or Medicine for photobiology research.

    In our discussion, everyone agreed that this is an inspiring discovery for understanding the mechanisms connecting light and physiology.

    For those of us who have worked in lighting for many years, the news deserves particular attention. Light does more than allow us to see objects; it can also participate in the transmission of biological signals. Science is increasingly providing answers to fundamental questions: Where does light act? Through what mechanisms? And what effects does it produce?

    However, the more exciting a discovery is, the more important it is to describe it accurately.

    This Nobel Prize was not awarded for a particular “healthy light,” nor does it demonstrate that everyday lighting can alter human genes. It recognizes the discovery of light-gated ion channels and optogenetics—a method that allows researchers to use light to precisely intervene in the activity of specific cells.[1]

    1 | From 2017 to 2026: Two Different Scientific Paths

    In 2017, Jeffrey C. Hall, Michael Rosbash, and Michael W. Young were awarded the Nobel Prize in Physiology or Medicine for their discoveries concerning the molecular mechanisms controlling circadian rhythms.

    Their research revealed that the biological clock is not merely an abstract metaphor. Gene expression, protein accumulation, and feedback regulation within cells can form a continuously operating rhythmic mechanism that enables organisms to anticipate daily changes. These mechanisms are associated with physiological processes including sleep, hormone secretion, body temperature, and metabolism.

    It is important to clarify that the 2017 prize recognized the molecular mechanisms of the biological clock. It was not awarded for the health effects of a particular lighting product, nor was it the first discovery that light affects the human body.

    How light enters the circadian regulation system is part of another line of research. A key study published in 2002 identified intrinsically photosensitive retinal ganglion cells and their connection to circadian regulation. This provided an important foundation for subsequent understanding of melanopsin, ipRGCs, and the non-visual effects of light.

    In 2026, Karl Deisseroth, Peter Hegemann, and Georg Nagel were recognized for showing another possibility: using light-sensitive proteins to turn specific cells into targets that can receive optical commands.[1]

    The two Nobel Prizes are not successive confirmations of the same mechanism.

    One revealed how life keeps time; the other developed a tool for controlling cellular activity with light. For light research, together they broaden our understanding of how light can interact with living systems.

    2 | Optogenetics: Turning Light into a Cellular Control Signal

    The key to this research came from light-sensitive proteins found in microorganisms.

    Take channelrhodopsin-2 (ChR2) from green algae as an example. It can both sense light and function as an ion channel in the cell membrane. Research published in 2003 demonstrated that when ChR2 is expressed in animal cells, light can directly open the channel, allowing cations to flow across the membrane.

    Researchers subsequently introduced genes encoding these proteins into neurons. Cells that originally lacked this light-sensing capability thereby acquired an optical control interface.

    Light-sensitive protein absorbs a photon → protein changes conformation → channel opens → ions flow → membrane potential changes → the neuron may fire.

    The actual photon absorber is the retinal chromophore within the protein. After absorbing light, it undergoes isomerization, driving the protein into a different photochemical state and changing the conductance of the channel.

    Under typical resting conditions in a neuron, opening ChR2 produces a net inward cation current, depolarizing the cell. Once a sufficient threshold is reached, the neuron’s own voltage-gated channels generate an action potential.

    Light is the triggering signal here. Neural firing still depends on the cell’s existing ion gradients, electrophysiological state, and channel systems.

    In 2005, a landmark study by Boyden, Deisseroth, Nagel, and colleagues demonstrated the ability to control neuronal firing on a millisecond timescale using brief pulses of light.[2] Researchers subsequently developed light-driven inhibitory tools, meaning that light could be used not only to activate neural activity but also to suppress it.

    © The Nobel Committee for Physiology or Medicine. Ill. Mattias Karlén

    3 | Why Is This a Major Breakthrough in Research Methodology?

    Observing that certain neurons become active during a particular behavior does not mean that we know those neurons cause the behavior.

    They could be the cause, the consequence, or simply be involved in another process occurring at the same time.

    Optogenetics enables researchers to intervene directly: activate a particular class of cells and observe whether a response occurs; inhibit them and see whether the response is reduced; change the timing of stimulation and examine how the outcome changes.

    This gives neuroscience a much stronger ability to test causality rather than stopping at observations of correlation.

    Of course, a single intervention cannot automatically explain all the causes of a complex behavior. The accuracy of cell targeting, possible unintended effects of optical stimulation, and the adequacy of experimental controls all remain critical to the reliability of the conclusions.

    For us, this methodology is particularly worth learning from: research into light and health requires clearly defined intervention conditions, as well as experimental designs capable of ruling out alternative explanations.

    4 | It Is Not a “Magic Wavelength” That Makes the Difference

    Early ChR2 studies commonly used blue light around 470 nm. The 2005 experiment used a 450–490 nm range and compared short stimulation pulses of 5, 10, and 15 milliseconds.[2]

    Different light-sensitive tools developed later can operate at different wavelengths. For example, the light-driven chloride pump NpHR uses yellow light to inhibit neural activity, while ChrimsonR, used in some visual-restoration research, is stimulated with orange light around 595 nm.

    This does not mean that blue light is inherently associated with “excitation,” or that orange light is inherently associated with “vision restoration.”

    The effect depends on which protein is expressed by the target cell and whether the light can effectively reach the target.

    Likewise, dose cannot be adequately described using a single total-energy value. At a minimum, we need to specify:

    1. Wavelength and spectral distribution;
    2. Irradiance or photon flux at the target cells;
    3. Pulse duration, intervals, and stimulation sequence;
    4. Expression level, activation/deactivation kinetics, and recovery state of the photosensitive protein;
    5. Absorption and scattering of light within the tissue.

    The photocurrent generated by ChR2 exhibits a peak, followed by decay and recovery. Continuous illumination and short pulses can produce different firing patterns even when the total exposure is the same. Subsequent models of the photocycle were developed precisely to describe these dynamic changes.

    Therefore, wavelength is only the starting point. Where the light reaches the tissue, and the temporal pattern in which it arrives, can be equally important.

    5 | From Research Tool to Medical Application

    Optogenetics has now entered human research.

    In 2021, Nature Medicine reported partial recovery of visual function in a blind patient. Researchers delivered a vector encoding ChrimsonR into the eye and used specialized goggles to convert visual information into light pulses projected onto the retina.

    After treatment, and while wearing the goggles, the patient was able to perform certain tasks involving object perception, localization, counting, and reaching. Without the goggles, the patient did not demonstrate the same ability to detect objects.[3]

    This was an important clinical exploration, but its implications have clear boundaries: it did not restore normal vision, and it was not an effect produced by ordinary lighting.

    The promise came from a specific biological target, gene delivery, an optical system, and functional validation. None of these components can simply be omitted.

    6 | The Lighting Industry: Moving from “What Light Is There?” to “What Light Does a Person Actually Receive?”

    Everyday lighting and optogenetics operate through different mechanisms. However, the precise description of stimulation conditions in optogenetics provides valuable inspiration for lighting research.

    We are accustomed to describing light from the product side: power, luminous flux, correlated color temperature, color rendering, and spectrum.

    When the question concerns physiological responses in people, we also need to know: after light passes through a space, reflection, obstruction, and patterns of use, how much actually reaches the eye, when does it arrive, and for how long?

    This is the shift from source specifications to actual human exposure.

    CIE S 026 establishes a measurement framework for describing the stimulation of five classes of photoreceptors in the human eye. Mel-EDI is one of the metrics used to describe melanopsin-related stimulation, but it is not a direct measure of sleep quality, cognitive performance, or overall health outcomes.

    A field measurement can tell us whether a particular stimulation condition has been achieved. Determining the resulting human outcome requires the corresponding research evidence.

    Likewise, photobiomodulation research involving red or near-infrared light should not borrow the mechanism of optogenetics as evidence of efficacy. Different pathways require their own exposure models, dose-response relationships, and evidence of effects.

    6 | What Should Future Light Research Prioritize?

    From the LRS perspective, we believe three areas deserve continued attention.

    01. Make Research Conditions Reproducible

    Without clear information about the spectrum, measurement location, timing protocol, and equipment, research findings are difficult to compare and even more difficult to translate into reproducible applications.

    CIE TN 016:2026 proposes the ENLIGHT checklist for reporting optical characteristics in laboratory-based human light-intervention studies, with the aim of improving research reproducibility and comparability. It is not a standard specifically for optogenetics, but it reflects the same fundamental requirement: the light stimulus must be described clearly and completely.

    02. Include the Space and the User in Design and Validation

    The same luminaire can produce different ocular exposure depending on the space, viewing direction, and time of use. Research and design should not stop at the light source. They should also establish the connection between spatial models, actual measurements, and records of real-world operation.

    03. Match Every Efficacy Claim to Its Evidence

    “More comfortable,” “supports circadian regulation,” “improves sleep,” and “enhances learning performance” are not interchangeable claims. Each outcome requires an appropriate study population, measurement method, and control condition.

    Mechanistic discoveries can help us formulate better hypotheses; product efficacy still has to be answered by evidence concerning the product and the context in which it is used.

    8 | LRS: Build Light for Life

    Today’s board discussion left me feeling both inspired and responsible.

    Inspired because light research is continually expanding our understanding of life.

    Responsible because the industry must understand these discoveries accurately—neither overlooking them nor turning them into claims that go beyond the evidence.

    Lighting Recipe Studio (LRS) focuses on research into healthy lighting environments, sensing technology, testing and monitoring equipment, algorithm capabilities, and spatial application systems. We care not only about lighting outcomes, but also about the true relationships between light, people, space, time, and activities. Our aim is to explain important research clearly, distinguish between different mechanisms, and strengthen the connection between design, measurement, and real-world validation.

    What the Nobel Prize gives us is not a health label that can simply be attached to a luminaire.

    It shows us that patiently pursuing a fundamental question can ultimately lead to discoveries that transform the way research is conducted.

    The relationship between light and health involves mechanisms that can be studied and outcomes that can be tested. The value created by the lighting industry in its next stage will depend on whether we can turn this knowledge into designs and applications that stand up to rigorous validation.

    Light and health are not pseudoscience.
    Ensuring that every health claim can be traced back to evidence is work we all share
    — LRS

    Further Reading and Original Sources

    [1] Official 2026 Nobel Prize in Physiology or Medicine Announcement
    Award topic: The discovery of light-gated ion channels and optogenetics.

    https://www.nobelprize.org/prizes/medicine/2026/press-release

    [2] Landmark 2005 Optogenetics Paper
    Boyden ES, Zhang F, Bamberg E, Nagel G, Deisseroth K.
    Millisecond-timescale, genetically targeted optical control of neural activity.
    Nature Neuroscience, 8, 1263–1268 (2005).

    The study demonstrated the use of ChR2 expression to control neuronal activity on a millisecond timescale using pulses of light.

    https://doi.org/10.1038/nn1525

    [3] 2021 Study on Partial Recovery of Visual Function in Humans
    Sahel JA et al.
    Partial recovery of visual function in a blind patient after optogenetic therapy.
    Nature Medicine, 27, 1223–1229 (2021).

    The study combined gene delivery with specialized light-stimulation goggles and reported partial recovery of visual function in a blind patient. The effect was not produced by ordinary lighting.

    Anmerkung: The board discussion was compiled from the author’s meeting notes. The scientific interpretation and industry recommendations in this article were written by the author and do not constitute direct quotations from individual scientists or an official position statement of GLG. The cover image is a conceptual visual creation and does not represent an experimental apparatus or clinical treatment setting.

  • Understanding Light 18 | The 18-Part Series on Healthy Lighting / Comprehensive Lighting Basics

    September 23, 2026

    Acceptance Is Not a One-Time Lux Measurement: How to Close the Design–Commissioning–Verification Loop

    Turning “design intent” into evidence that can be retested and sustained in operation

    Author | Lawrence Lin

    Chairman, GLGA | Board Member, GLG | IWBI WELL Light Concept Advisor | Founder & CEO, LRS

    On the day a project is completed, all the lights are switched on, workplane illuminance is measured, and the acceptance form is signed. Three months later, the schedule has been modified by the facility team, the blinds remain closed most of the time, several sensors are offline, and the nighttime scene is no longer being used. The health-oriented lighting specified on paper has quietly become ordinary lighting.

    Acceptance of an integrated lighting system is not a snapshot taken at a single point in time. It is a verification of an operating logic. Design, installation, commissioning, measurement, occupant feedback, and ongoing review are all essential. Missing any one of these links can cause the intended outcome to fail.

    Before Acceptance: Lock Down the Baseline

    The final drawings should document the luminaires, drivers, control addresses, scene schedule, measurement points, and target values. Any equipment substitution must trigger a review of spectral characteristics, photometric distribution, and dimming performance. Field measurement instruments should have documented calibration information, and measurement personnel should follow consistent orientations, timing, and recording formats.

    For spaces where daylight contributes to the lighting environment, weather or blind conditions should be defined in advance. When weather cannot be controlled, daylight and electric-light conditions can be recorded separately rather than directly comparing readings taken on different days.

    During Commissioning: Check the System Scene by Scene

    Testing should go beyond rated full-output operation. Daytime, evening, pre-sleep, nighttime safety, cleaning, and maintenance scenes should all be checked.

    Verify workplane illuminance, eye-level mel-EDI, glare observation points, color characteristics, minimum stable dimming levels, and temporal light modulation. At the same time, test sensors, manual overrides, power-loss recovery, and shading integration.

    When a deviation is found, the team should be able to trace whether it was caused by the luminaire, driver, installation angle, surface reflectance, daylight, or control logic. Simply “turning the system up a little” often masks the real problem.

    After Handover: Verify Real-World Use

    Handover documentation should be understandable to the facility team: why each scene exists, which parameters should not be changed arbitrarily, and what needs to be remeasured after equipment replacement.

    After the system has been in operation for a period of time, key eye positions and scenes can be spot-checked, control logs reviewed, and occupants interviewed about glare, insufficient light, frequent changes in lighting levels, or difficulties operating the system.

    Subjective human feedback cannot replace measurement, and measurement cannot replace human experience. Together, they form a more complete body of operational evidence.

    A Minimum Closed-Loop Checklist

    During the requirements stage, define people, time, and activities. During the design stage, calculate visual and α-opic metrics. During procurement, lock down data and interfaces. During the mock-up stage, validate extreme operating conditions. During construction, document changes. During commissioning, test each scene. During operation, provide training, collect feedback, and conduct remeasurement.

    The purpose of this chain is not to create more paperwork. It is to ensure that every health-related claim has a source, defined conditions, and an accountable owner.

    What We Can Say Now / What We Cannot Yet Say

    What we can say: Through traceable measurement points, scenes, equipment data, and operational review, it is possible to demonstrate that a system meets its design targets under specified conditions.

    What we cannot yet say: A single post-construction measurement can prove long-term health outcomes, or that the system will remain compliant under every future operating condition.

    Three Things You Can Do Today

    • Upgrade the acceptance form from an “equipment checklist” to “scene + measurement point + conditions + result + responsible person.”
    • Include control logic, calibration information, and critical parameters in the operations manual.
    • Schedule a remeasurement and occupant follow-up 3–6 months after handover.

    Evidence label: Engineering practice / Open question.
    An on-site closed loop can verify performance implementation; long-term health outcomes still require appropriate research designs.

    References

    • CIE PS 001:2024：https://cie.co.at/publications/cie-position-statement-integrative-lighting-recommending-proper-light-proper-time-3rd
    • CIE S 026:2018：https://www.cie.co.at/publications/cie-system-metrology-optical-radiation-iprgc-influenced-responses-light-0
    • CIE TN 016:2026：https://www.cie.co.at/publications/comprehensive-checklist-reporting-light-characteristics-laboratory-based-human-studies
    • ISO/CIE 8995-1:2025：https://www.iso.org/standard/76342.html

  • Understanding Light 17 | The 18-Part Series on Healthy Lighting / Comprehensive Lighting Basics

    September 22, 2026

    From Light Recipes to Computable, Procureable System Specifications

    Only when a goal is written into requirements, interfaces, and tolerances does it have a chance of being realized in the field.

    Author | Lawrence Lin

    Chairman, GLGA | Board Member, GLG | IWBI WELL Light Concept Advisor | Founder & CEO, LRS

    Many proposals describe “energizing morning light, focused midday light, and calming evening light.” The language sounds appealing, but when it comes time to tender, no one knows exactly what to buy. Once the luminaires arrive on site, different manufacturers use different protocols, leaving commissioning personnel to adjust the colors by feel.

    A light recipe is not simply a set of scene names. It is a set of performance targets tied to people, locations, time periods, and activities. To move from concept to engineering implementation, it must pass through calculation, mock-ups, procurement data, and control interfaces.

    What a Qualified Scene Specification Should Include

    Start by defining the intended users and activities, followed by the operating period and duration. Then specify workplane illuminance, eye-level mel-EDI, glare, color quality, dimming range, and temporal light modulation requirements. Finally, clearly define measurement points, orientations, tolerances, daylight conditions, and how manual overrides are handled.

    For example, a “daytime office scene” should not simply specify 250 lx mel-EDI. It should also define the seated eye position, primary viewing direction, target coverage ratio, visual requirements at the workplane, blind/curtain condition, and maintained operating period. Nighttime scenes must simultaneously preserve safety for circulation and task performance.

    Procurement Is Not About Buying a Single Number

    Suppliers should provide spectral data at different CCTs and dimming levels, photometric distribution files, color-quality data, efficacy, temporal light modulation characteristics, and control-system compatibility. If they provide only a single-point test at rated power, the design team cannot predict actual scene performance.

    The system specification should also define the driver’s minimum stable output, dimming curve, addressing and grouping, sensors, shading integration, data logging, and maintenance/replacement principles. Otherwise, replacing the driver—even with the same luminaire model—may alter the entire light recipe.

    What Role Do Instruments Play Here?

    Method comes before instrumentation. First define the questions that need to be answered, then select illuminance meters, spectroradiometers, luminance measurement equipment, and temporal light modulation measurement devices.

    Using an integrated measurement tool such as In. Licht as an example, its value is not in making design decisions on behalf of the team. Rather, under consistent measurement points and scene conditions, it can record spectral data, illuminance, and α-opic quantities, helping the team compare the design intent with field conditions.

    Without a clearly defined measurement protocol, even the best instrument will only generate more isolated numbers.

    What We Can Say Now / What We Cannot Yet Say

    What we can say: An executable light recipe should include targets, conditions, equipment data, control logic, tolerances, and a verification method.

    What we cannot yet say: Purchasing a certain type of tunable luminaire or measurement instrument is equivalent to completing an integrated lighting system.

    Three Things You Can Do Today

    • Rewrite every scene as “people + activity + time period + target + measurement point + control.”
    • Standardize the formats for spectral, photometric, dimming, and control data before tendering.
    • Use a 1:1 mock-up to validate the brightest, typical, and minimum-dimming conditions.

    Evidence label: Engineering practice. Performance-based specifications and traceable data can improve the likelihood of successful implementation; specific tolerances should be established on a project-by-project basis.

    References

    • CIE S 026:2018：https://www.cie.co.at/publications/cie-system-metrology-optical-radiation-iprgc-influenced-responses-light-0
    • ANSI/IES RP-46-25：https://store.ies.org/product/recommended-practice-supporting-the-physiological-and-behavioral-effects-of-lighting-in-interior-daytime-environments/
    • CIE TN 012:2021：https://cie.co.at/publications/guidance-measurement-temporal-light-modulation-light-sources-and-lighting-systems

    Next—and the final article in this series: Why acceptance testing cannot rely on a single lux measurement, and how to create a true closed loop between design, commissioning, and verification.

  • Understanding Light 16 | The 18-Part Series on Healthy Lighting / Comprehensive Lighting Basics

    September 21, 2026

    Define the Person First, Then Define the Light: A Five-Dimensional Needs Model

    Use “Light — People — Space — Time — Activity” to avoid choosing luminaires before understanding the problem.

    Author | Lawrence Lin

    Chairman, GLGA | Board Member, GLG | IWBI WELL Light Concept Advisor | Founder & CEO, LRS

    The most common opening question in a lighting design meeting is: “Should we use 4000 K or 3500 K here?”

    When a team starts with product specifications, it has often already skipped the more important questions: Who is here? When do they arrive? What are they doing? How long do they stay? Where are they looking?

    I use five dimensions to organize healthy-lighting requirements: Light, People, Space, Time, and Activity.

    These are not a new standard, but a practical framework for avoiding omissions. Once the relationships are clear, luminaires and controls have a meaningful basis for selection.

    Light: What Can We Design and Measure?

    This includes spectrum, quantity, direction, distribution, duration, rate of change, color rendering, glare, and temporal light modulation.

    There are both visual metrics and α-opic metrics. Every objective should have a corresponding measurement method.

    People: Who Actually Uses the Space?

    Record age, visual capability, primary sleep-wake schedule, work shifts, special sensitivities, and the need for personal control.

    Simply writing “office workers” or “residents” is not enough to become a meaningful design input.

    Space: How Does the Architecture Shape the Light?

    Windows, orientation, scale, material reflectance, furniture, and partitions all reshape light.

    A good spectrum installed with the wrong optical distribution in a dark interior may still fail to deliver the intended exposure to the eyes.

    Time: When Does the Objective Need to Be Met?

    At a minimum, divide the day into primary daytime activities, evening, the three hours before sleep, sleep, and short nighttime activities.

    Not every project needs constant dynamic changes, but it must be clear when the light should be higher and when it should be lower.

    Activity: What Does the Person Need to Do Right Now?

    Reading, precision work, communication, relaxation, getting up at night, caregiving, and screen-based work have different requirements for illuminance, direction, glare, and control.

    The same room may serve multiple activities throughout the day. This is where different lighting scenes emerge.

    Translating the Five Dimensions into a Patient Room

    During the day, patients may need a bright environment with useful temporal cues; doctors need adequate light for examination and reading; visitors need a comfortable environment for communication.

    At night, patients need a quiet, low-stimulation environment, while caregivers still need sufficient light to work safely.

    The design therefore cannot simply assign one “patient-room illuminance” to the entire space. It needs to establish different but compatible lighting scenes for different people, times, and activities.

    What We Can Say Today / What We Cannot Yet Say

    What we can say today: A five-dimensional model can translate the vague idea of “human-centered design” into discussable and calculable inputs while reducing product-first decision-making.

    What we cannot say: Completing the five categories automatically produces a health outcome. The framework still requires standards, professional judgment, and on-site evidence.

    Three Things You Can Do Today

    • Before developing the design, hold a requirements meeting that discusses people, time, and activity—without discussing luminaire models.
    • For every major scenario, write one sentence describing “who is doing what, and when.”
    • For every objective, specify the measurement point, direction, time period, and verification method.

    Evidence label: Practice framework.
    This framework is intended to organize requirements; it does not claim to establish scientific thresholds or constitute a certification system.

    References

    • CIE — Integrative Lighting：https://cie.co.at/eilvterm/17-29-028
    • CIE PS 001:2024：https://cie.co.at/publications/cie-position-statement-integrative-lighting-recommending-proper-light-proper-time-3rd
    • ISO/CIE 8995-1:2025：https://www.iso.org/standard/76342.html

    In the next article, we move this needs map one step further: How do we turn a “light recipe” into system specifications that can be calculated, procured, and commissioned?

  • Understanding Light 15 | The 18-Part Series on Healthy Lighting / Comprehensive Lighting Basics

    September 18, 2026

    Daylight, Electric Light, and Controls: Who Is the Protagonist?

    The true protagonist is not a device, but a stable and appropriate luminous environment throughout the day.

    Author | Lawrence Lin

    Chairman, GLGA | Board Member, GLG | IWBI WELL Light Concept Advisor | Founder & CEO, LRS

    Some projects interpret healthy lighting as simply purchasing a tunable-color-temperature lighting system. Others assume that large windows eliminate the need to consider electric lighting. Both perspectives underestimate the realities of architecture: daylight is abundant but variable; electric light is stable but requires energy; and controls determine whether the two can work together at the right time.

    Daylight is generally an important resource for obtaining higher levels of daytime light exposure; electric light supplements, balances, and extends it; controls organize both according to time, weather, shading, and activity, turning them into a usable system.

    The Value—and Cost—of Daylight

    Daylight can provide high illuminance, a rich spectrum, and strong temporal cues, while also connecting people with the outdoor environment.

    But it can also introduce glare, overheating, reflections, and uneven illumination. Areas near windows may be excessively bright while the deeper parts of the space remain insufficiently illuminated.

    Therefore, “more windows” is not a complete strategy. Building orientation, window-to-wall ratio, shading, glazing, interior reflectance, and workstation orientation all need to be considered together.

    Good daylight design often begins during the early architectural stages, rather than being treated as a problem to fix during fit-out.

    Electric Light Is Not a Replica of Daylight

    The advantage of electric light is that it is controllable and stable, and can supplement light at the eyes and on task surfaces when needed.

    It does not need to mechanically reproduce the sky’s color temperature every minute. Instead, it should compensate for insufficient daylight, control glare, and maintain visual quality.

    In deeper areas of a space, bright wall surfaces, large soft luminous surfaces, or indirect lighting can increase luminance within the field of view. At night, the system should be capable of substantial dimming while retaining safe and easy-to-use local lighting.

    Controls Determine Whether the Design Survives

    An automated system without proper commissioning may switch frequently on cloudy days, or even work against the shading system. At a minimum, the control strategy should specify the sensor locations, schedules, dimming curves, minimum output levels, manual override methods, and power-loss recovery logic.

    The system only delivers lasting results if users are willing to use it. Manual control is not a failure; it should be designed in as a feedback channel.

    What We Can Say Today / What We Cannot Yet Say

    What we can say today: Daylight, electric light, shading, and controls should work together to create a luminous environment that changes over time without becoming excessively disruptive.

    What we cannot say: Having windows automatically satisfies all daytime objectives, or installing tunable-white lighting automatically makes a space a circadian lighting system.

    Three Things You Can Do Today

    • During the early architectural stages, simulate daylight, glare, and light exposure in the direction of the eyes together.
    • Establish a small number of clear control scenarios for sunny days, cloudy days, early morning, daytime, and nighttime.
    • After commissioning, observe whether users frequently override the automated controls and use that feedback to refine the control logic.

    Evidence label: Established consensus / Cautious application.
    Integrating daylight and electric light is a robust direction; specific dynamic strategies still require project-level validation.

    References

    • CIE PS 001:2024 ：https://cie.co.at/publications/cie-position-statement-integrative-lighting-recommending-proper-light-proper-time-3rd
    • ISO/CIE 8995-1:2025 ：https://www.iso.org/standard/76342.html
    • CIE Technical Reports — Daylight and Glare：https://cie.co.at/publications/technical-reports

    In the next article, we build a map for design: Define the person first, then define the requirements across five dimensions—light, people, space, time, and activity.

  • Understanding Light 14 | The 18-Part Series on Healthy Lighting / Comprehensive Lighting Basics

    September 16, 2026

    Invisible Flicker Is Still Part of Lighting Quality

    Moving from “the eye can’t see it” to measurable temporal light modulation

    Author | Lawrence Lin

    Chairman, GLGA | Board Member, GLG | IWBI WELL Light Concept Advisor | Founder & CEO, LRS

    In a mock-up room, the naked eye cannot see the light flickering, yet a smartphone camera shows black bands across the image. The supplier says, “The phone isn’t professional, so that doesn’t mean there is a problem.” Meanwhile, the user worries that “invisible flicker must damage the brain.” Both statements are too absolute.

    When light output varies over time, this is called temporal light modulation (TLM). It can produce visible flicker, the stroboscopic effect when objects are moving, or the phantom array effect during rapid eye movements. Whether it is perceived or causes discomfort depends on frequency, modulation depth, waveform, luminance, field of view, and the observer.

    A Smartphone Can Provide a Clue, Not a Quantitative Measurement

    A camera’s rolling shutter can amplify or create visible bands. It can therefore be useful for quickly identifying potential issues, but it cannot replace appropriate measurement equipment.

    Rigorous measurement requires a sufficiently high sampling rate, an appropriate photodetector, clearly defined measurement conditions, and analysis of the light-output waveform over time.

    “Flicker percentage” is not a universal metric either. The same modulation depth can produce very different visual effects at different frequencies and with different waveforms. Projects should use evaluation metrics and limits appropriate to the application.

    Dimming Is Often Where Problems Appear

    Many luminaires perform well at rated full power, but temporal light modulation can increase significantly when dimmed to 10% or paired with a different controller. Tunable-white systems can also develop new waveforms when two light sources are mixed.

    Therefore, testing should not be limited to the “best factory condition.”

    Residential nighttime settings, classroom demonstrations, office energy-saving modes, and low-light hotel scenes may all operate in low-dimming ranges—which are precisely the conditions that deserve to be tested.

    Healthy Lighting Cannot Focus Only on Circadian Effects

    If a system uses unstable low-level dimming to reduce nighttime mel-EDI, it may simply exchange one problem for another.

    Integrated design requires the spectrum, luminance, controls, and LED driver to work together as a complete system.

    What We Can Say Today / What We Cannot Yet Say

    What we can say today: Temporal light modulation can be measured and may produce multiple forms of visual artifacts; the driver and dimming state are critical conditions.

    What we cannot say: The absence of visible bands on a smartphone proves “zero flicker,” or that every form of imperceptible modulation causes the same type of health effect.

    Three Things You Can Do Today

    • Measure at 100% output, the typical operating level, and the lowest commonly used dimming level.
    • Test the luminaire, driver, and controller as one complete system.
    • Product documentation should state the measurement method, frequency, waveform, and operating conditions, rather than simply claiming “flicker-free.”

    Evidence label: Established consensus / Open question.
    Standardized methods exist for measuring visual artifacts and some of their effects; broader long-term health effects still require further research.

    References

    • CIE TN 012:2021：https://cie.co.at/publications/guidance-measurement-temporal-light-modulation-light-sources-and-lighting-systems
    • CIE 249:2022：https://www.cie.co.at/publications/visual-aspects-time-modulated-lighting-systems
    • IES TM-18-18：https://store.ies.org/product/tm-18-18-light-and-human-health-an-overview-of-the-impact-of-optical-radiation-on-visual-circadian-neuroendocrine-and-neurobehavioral-responses/

    In the next article, we bring the discussion back to architecture: Daylight, electric light, and controls—which one is truly the protagonist of healthy lighting?

  • Europe’s Lighting Leaders: Where Will the Next Growth Come From?

    September 15, 2026
    Europe’s Lighting Leaders: Where Will the Next Growth Come From?

    Europe’s Lighting Leaders: Where Will the Next Growth Come From?

    By Lawrence Lin
    Founder, Lighting Recipe Studio · Chair, GLGA
    Former Global CEO, LEDVANCE

    European industry perspective · Information cut-off: 7 September 2026

    Europe’s lighting companies have become fluent in explaining difficult markets. Weak construction, deferred investment, price pressure and the contraction of conventional lamps recur throughout their financial commentary. The responses are familiar too: restructuring, simpler organisations, fewer products, asset disposals and leadership changes.

    These pressures are real. Protecting cash and restoring profitability are essential responsibilities. Yet an uncomfortable question remains: can the industry explain its next source of customer value as clearly as it explains its recent decline?

    Europe has built substantial expertise in optics, industrial design, architectural specification and application engineering. That heritage creates an opportunity, and a reasonable expectation of leadership. Customers should be able to see what these capabilities will deliver next—in their buildings, their working environments and their homes.

    The concern is that a mature market can gradually become an excuse for limited ambition. Energy efficiency and environmental responsibility remain indispensable. They cannot, on their own, explain why a customer should choose one competent supplier over another.

    The next phase of growth will depend on meaningful research, better products and reliable delivery. If established lighting businesses do not turn those capabilities into solutions customers value, the brands that organise lighting within intelligent homes and buildings may increasingly come from elsewhere.

    Author’s disclosure: I previously served as Global CEO of LEDVANCE and as Senior Adviser, Asia Pacific, to Zumtobel Group, with the latter appointment ending on 30 June 2026. This article reflects on an industry whose management decisions I have also helped shape. Company assessments below draw on the sources identified in the references.

    Financial resilience is only part of the answer

    Recent results show considerable variation. Some businesses have improved profitability without much revenue growth. Others have expanded into adjacent electrical products, while several major lighting groups have experienced pressure on both sales and margins.

    Business Revenue development Operating profitability What the figures invite us to examine
    Signify €6.704bn in 2023 to €5.765bn in 2025 Adjusted EBITA margin: 10.0% to 8.9% Whether connected products and services can offset the contraction elsewhere
    Zumtobel Group €1.127bn in FY2023/24 to €1.040bn in FY2025/26 Adjusted EBIT margin: 5.1% to 4.1% Different recovery prospects in luminaires and components
    Fagerhult Group SEK8.560bn in 2023 to SEK7.891bn in 2025 Operating margin: 10.5% to 7.7% Whether a broad brand portfolio produces sufficient differentiation and returns
    Luceco £209.0m in 2023 to £271.4m in 2025 Adjusted operating margin: 11.5% to 12.5% How much growth comes from existing operations and how much from acquisitions
    F.W. Thorpe Approximately £175–177m across FY2023–FY2025 Statutory operating margin: approximately 15.8% to 18.3% How specialised delivery and service support profitability

    These are group figures, including international operations and, in some cases, substantial non-lighting activities. Fiscal calendars and profit definitions differ. The table compares each business with its own earlier performance; it is not a ranking of comparable European lighting margins. Sources: the company reporting resources listed below.

    Low growth is not necessarily poor management. A mature business can create considerable value through dependable cash generation and disciplined investment. However, leadership also involves developing future demand. A stronger margin after restructuring is welcome; it does not establish that customers have acquired a new reason to buy.

    Europe needs a broader proposition for light

    For building owners, the relevant decision is often whether an upgrade justifies disruption, installation costs and a long-term maintenance commitment. A more efficient luminaire helps, but the full proposition includes design, compatibility, commissioning, reliability and service.

    Europe’s renovation agenda creates room for that broader offer. The revised Energy Performance of Buildings Directive treats lighting and building automation within the wider performance of technical building systems. The commercial opportunity lies in helping owners achieve workable improvements in existing buildings, where equipment from different generations and suppliers must coexist. [1]

    This calls for practical innovation. Can an installer commission a system more quickly? Can an owner replace a failed component without replacing the entire installation? Can lighting work reliably with other building controls? Can a designer improve visual comfort while retaining flexibility for future changes of use?

    Environmental claims also need to become more tangible. Repairability, durable components, documented material choices and accessible maintenance can influence purchasing decisions when they reduce lifecycle cost or uncertainty. Repeating a general commitment to sustainability provides much less differentiation.

    Price competition deserves the same scrutiny. It can reflect excess capacity and purchasing pressure, but it can also reveal that buyers see too little difference between competing offers. Management cannot control the construction cycle. It can influence whether its products remain interchangeable in the customer’s eyes.

    Signify: a connected installed base still needs an economic case

    Signify illustrates the scale of the transition. Sales fell by approximately 14% between 2023 and 2025, while its adjusted EBITA margin declined from 10.0% to 8.9%. Free cash flow remained substantial: €586m in 2023, €438m in 2024 and €440m in 2025. Cash provides capacity to invest, but it does not remove the growth challenge. [2]

    The reported connected light-point base increased from 124 million in 2023 to 167 million in 2025. This is an important measure of deployment, but a cumulative installed base is not equivalent to recurring revenue or a disclosed number of paying software customers.

    The commercial test is whether connectivity improves retention, supports additional services and produces acceptable returns after development and support costs. The industry needs greater clarity on those outcomes before treating connected volume as proof of a transformed business model.

    Signify’s June 2026 strategy set medium-term ambitions of 0–1% comparable sales growth, approximately 10% adjusted EBITA margin and a 7–8% free-cash-flow margin. Those targets acknowledge a restrained growth environment. They also make the quality of resource allocation especially important. [39]

    As Tempelman’s arrival from the energy sector brings experience relevant to this broader agenda. His appointment creates an opportunity to connect lighting expertise with building and energy requirements. The evidence of success will come from execution, customer adoption and cash returns. [3]

    Zumtobel and Tridonic: two recovery challenges within one group

    Zumtobel’s results show why a group average can obscure the operating task. In FY2025/26, lighting revenue declined by 3.7%, yet adjusted EBIT rose from €51.3m to €54.7m. Components revenue fell by approximately 11%, with adjusted EBIT declining from €13.5m to €4.6m. The two businesses require different responses. [4]

    For professional luminaires, specification, design and application support can help defend value. For components, technical differentiation has to withstand demanding procurement processes and competitive pricing. A driver or control device becomes more valuable when it improves system performance or reduces integration effort; connectivity alone does not ensure pricing power.

    Heiner Lang joined the management board on 1 September 2026 and is scheduled to become CEO on 1 October. His industrial automation background is relevant to the group’s development, while preserving its optical and application knowledge will remain essential. [5]

    First-quarter FY2026/27 sales were €264.1m, down 0.9%, with adjusted EBIT of €8.2m and a 3.1% margin. These results precede the incoming CEO’s tenure and should be assessed accordingly. A leadership transition can establish priorities, but recovery must be demonstrated over subsequent reporting periods. [6]

    Fagerhult, Luceco and F.W. Thorpe: different routes to value

    Fagerhult’s portfolio includes businesses built around architectural specification, local professional markets and infrastructure. Its revenue fell by approximately 7.8% between 2023 and 2025, and operating cash flow declined from SEK1.209bn to SEK740m. Brand breadth has not insulated the group from weaker demand. [7]

    The acquisitions of Trato TLV and Capelon add exposure to specialised applications and connected outdoor lighting. Their strategic logic is understandable. Their long-term value depends on whether they improve customer access and capabilities at a return that justifies the capital invested.

    Multiple brands can preserve local expertise and distinct relationships with specifiers. They can also duplicate costs. The relevant question is whether each business has a clear role and whether shared resources make the portfolio more effective.

    Luceco presents a different picture. Revenue and adjusted operating profitability improved between 2023 and 2025, with free cash flow reaching £30.4m in 2025. Its activities extend across wiring accessories, LED lighting, EV charging and portable power. Acquisitions, including D-Line and CMD, contributed to the expansion. These are the results of a broader electrical-products business, not a measure of organic lighting-market growth. [8]

    Its experience makes adjacency worth studying. Products that share customers, installation channels and engineering capabilities may offer a credible route to expansion. Diversification becomes less convincing when it merely increases the number of separate businesses management must support.

    F.W. Thorpe offers another model. Revenue remained broadly stable across FY2023–FY2025, while statutory operating margins improved. In FY2025, operating cash flow was £33.2m and cash plus short-term financial assets reached £61.8m. [9]

    Thorlux’s offer extends from surveys and design through installation, commissioning and after-sales support. Continued development of SmartScan connects product engineering with the practical operation of installations. This is a concrete example of innovation within an established specialism.

    A useful vision does not require every lighting company to build a universal platform. It can involve doing a demanding application exceptionally well and making the customer’s work easier.

    The private companies complicate the story of decline

    Europe’s lighting industry cannot be understood through a few listed groups alone. Privately owned manufacturers and design businesses reveal different investment choices. Their financial disclosure is often less extensive, so historical scale and current operational developments need to be distinguished.

    TRILUX is a substantial example. DDW lists 2023 revenue of approximately €696.4m, a historical scale reference rather than a current audited performance assessment. More tangible recent evidence comes from the company’s investment programme: a Polish production and development site opened in September 2024 with approximately €32m invested and designed capacity of up to one million luminaires annually. [10] [11]

    In July 2026, TRILUX announced more than €80m of investment over three years at Arnsberg, covering its headquarters and production modernisation. Ansorg and Oktalite had also been brought together within TRILUX Retail. These are identifiable commitments of capital and organisational effort. Their value will depend on utilisation, development efficiency and customer demand, but they make a blanket accusation of industry inactivity difficult to sustain. [12] [13]

    SLV Lighting Group is pursuing integration across a different portfolio. Its predecessor, nnuks, reported turnover above €230m in 2021. That figure establishes historical group scale; it is neither current revenue nor the turnover of the SLV brand alone. [14]

    The group’s 2025 sustainability report describes five brands—SLV, Nordtronic, Novalux, unex lighting and Knightsbridge—and measures to share procurement, logistics and sales capabilities. Nordtronic and SLV are centralising purchasing and logistics, while SLV supports Novalux’s expansion beyond Italy. Knightsbridge also participates in wiring accessories. [15]

    The strategic opportunity is to make a multi-brand group more useful to installers and distributors through availability, range and service. Public disclosure does not yet allow those changes to be translated into a reliable assessment of recent group profitability.

    ERCO demonstrates the importance of application-specific product development. Its 2026 introductions include flexible linear track lighting for offices, further wallwashing applications and developments for display lighting. Those improvements address identifiable design and use requirements. [16]

    Its scale should nevertheless be described cautiously. A business index lists approximately €81.8m for ERCO GmbH in 2024, without sufficiently clarifying the consolidation boundary. The available evidence does not confirm current global brand revenue above €100m. ERCO belongs in the discussion for its professional significance, rather than an assumed revenue threshold. [17]

    FLOS combines an active design programme with the financial complexity of a wider luxury-design group. An Italian company database lists approximately €134.2m of 2024 revenue for FLOS S.p.A.; this is a secondary summary of a legal entity’s accounts, not verified global consolidated FLOS-brand turnover. Product launches continued through the 2025 and 2026 Milan design weeks. [18] [19]

    At Flos B&B Italia Group, the first-half 2026 continuing-business pro forma figures, excluding Louis Poulsen and Fendi Casa, show revenue of €270.2m, down 6.5%, and adjusted EBITDA of €50.1m, down 17.5%. The 18.5% EBITDA margin is a group measure encompassing furniture and other design activities; it must not be attributed to FLOS lighting alone. [20]

    The agreement to sell Louis Poulsen illustrates how ownership and financing influence even highly regarded brands. Announced in June 2026, the transaction was expected to close in the second half, subject to approvals. A disposal can support debt reduction and a new ownership horizon; it does not, by itself, establish that the brand has failed. [21]

    EGLO adds the mass-market decorative-lighting perspective. Its official company profile reports €523m of revenue for 2024 across a portfolio extending beyond lighting alone. Comparable profit and cash-flow figures are not supplied alongside that disclosure. Scale is clear; the quality of recent returns is less visible. [22]

    Specialisation and controls still offer room to grow

    Glamox’s holding company, GLX Holding, reported preliminary 2025 revenue and other operating income of NOK4.447bn, down 0.9%, with adjusted EBITA of NOK680m and a 15.3% margin. Orders increased by 4.9%, while operating cash flow declined from NOK691m to NOK497m. These different movements show why orders, earnings and cash need to be considered together. [23]

    Schréder, whose 2023 turnover was reported at €560m by EY, is extending its outdoor-lighting position through the acquisition of NLS Lighting, announced in April 2026. Local manufacturing and project access in North America provide a plausible complement to its technical capabilities. The transaction price was not disclosed. [24] [25]

    Plejd is a useful counterexample to the assumption that lighting-related markets offer little growth. Its 2025 net sales reached SEK935m, up 41.1%, with an EBIT margin of 24.6%. Management described the growth as organic and identified contributions from adjacent smart products and international expansion. It should therefore be understood as growth in a broader control and installation proposition, not simply stronger demand for luminaires. [26]

    Dexelance’s lighting activities also grew in 2025, reaching €34.3m from €32.1m. This is a smaller segment within a broader design group, but it reinforces the need to examine individual markets rather than assume uniform contraction. [27]

    Turnarounds need equally careful interpretation. Edison’s company-commissioned research on Dialight reports higher group underlying operating profit for the year to March 2026 despite lower revenue. However, lighting-segment revenue and underlying profit before central costs both declined. Improvement elsewhere in a group, or lower overheads, should not automatically be presented as a recovery in lighting demand. [28]

    LEDVANCE and Inventronics: ownership does not remove the European operating challenge

    Europe’s lighting ecosystem includes businesses with international ownership, engineering teams, manufacturing and customers. Their strategic significance rests on what they deliver in European markets.

    LEDVANCE retains substantial brand recognition, distribution relationships and local operating capabilities. Its parent’s product-line disclosure reports 2025 revenue of RMB9.25bn and a gross margin of approximately 40%. These are worldwide product figures reported in the parent’s currency, not European regional revenue or a standalone operating margin. [29]

    The first half of 2026 illustrates the importance of that distinction. LEDVANCE product-line revenue was RMB4.326bn, down 1.12%, while its gross margin fell to 39.82%, a decline of 2.80 percentage points. Gross profit decreased by approximately RMB142m. The parent group’s profit recovery therefore cannot establish a recovery in LEDVANCE’s lighting operations. Separate product-line net profit and cash flow were not disclosed. [30]

    Large acquisition-related impairments in the parent’s 2025 accounts also require care: a reduction in the carrying value of an acquisition-related asset group is not an equivalent amount of annual operating loss at LEDVANCE GmbH.

    For European customers, the more immediate questions concern product development, service and project execution. The acquisition of loblicht adds professional project capabilities. LEDVANCE’s August 2026 management announcement emphasised European B2B and project activity, alongside more efficient customer processes. [31]

    Its renewables range raises a further strategic question. Lighting, photovoltaics, inverters and storage can share some channels and customers, but commercial synergies need evidence. Public product availability does not establish material revenue or acceptable returns. [32]

    Inventronics faces a related task following its acquisition of the former ams OSRAM digital-systems business in Europe and Asia. The acquisition brought engineering, products and customer relationships, but those assets still have to earn their returns. Its subsequent transition from licensed OSRAM branding to Inventronics increases the importance of its own product reputation and service continuity. [38] [38] [38]

    For both businesses, the European test is practical: customer retention, competitive technical performance, reliable availability and profitable execution. Ownership changes and portfolio expansion can support those outcomes; they cannot substitute for them.

    IKEA and Kingfisher: the customer relationship is already broader than lighting

    The industry’s future competitors need not begin as specialist luminaire manufacturers. Home-furnishing and home-improvement businesses can place lighting inside a purchase journey customers already understand.

    IKEA reported worldwide retail sales of €44.6bn in FY2025, down approximately 1%, while volumes and customer numbers increased by around 3% following price reductions. These figures cover the whole IKEA retail system, including non-lighting activities; they say nothing directly about lighting profitability. [33]

    More significant for lighting strategy was IKEA’s November 2025 announcement of 21 Matter-compatible smart-home products, including 11 KAJPLATS bulbs, sensors and remotes. Its proposition brings connected lighting into an accessible home-furnishing context. [34]

    The competitive implication is an inference from that offer: a retailer that helps people choose, install and use a system can become the brand associated with the experience, while individual device suppliers become less visible. Product launches alone do not establish that IKEA has achieved this at scale or profitably.

    Kingfisher offers another view of channel influence. In the year ended 31 January 2026, group sales were £12.945bn and adjusted pre-tax profit £560m. B&Q sales reached £3.971bn, with like-for-like growth of 3.3%. Own exclusive brands represented 43% of group sales across categories, including ranges such as GoodHome and LAP. That percentage is not a lighting-market share. [35] [36]

    The next quarter was less favourable for B&Q: sales fell 3% as reported and 4.1% like for like, although e-commerce grew. Channel ownership does not eliminate exposure to household spending and renovation cycles. [37]

    Neither IKEA nor Kingfisher provides enough separate lighting information here to compare its lighting profitability with manufacturers. Their strategic relevance is nevertheless clear: they influence assortment, price, convenience and the customer relationship. Lighting brands need to demonstrate what additional value they bring within that environment.

    Leadership requires a commitment that customers can recognise

    The evidence does not support a claim that European lighting companies have stopped innovating. TRILUX’s investments, ERCO’s application work, F.W. Thorpe’s systems and service, and Plejd’s expansion all provide concrete counterexamples.

    The sharper concern is whether those efforts are sufficient, sustained and commercially effective. Research expenditure alone cannot answer this. Companies differ in their development cycles, accounting policies and mix of software, electronics and optical engineering.

    A credible vision should identify the customer problem, the resources committed and the conditions that will determine success. For a building owner, that might mean lower lifecycle cost and more dependable maintenance. For an installer, less commissioning time and fewer callbacks. For a specifier, better visual performance and clearer integration choices. For a household, an intuitive system that continues to work as devices change.

    Claims about wellbeing should be tied to measured lighting conditions and appropriate evidence. A controllable spectrum or a new product label does not establish a health outcome. Professional credibility depends on communicating what has actually been demonstrated.

    Boards also need to examine what restructuring preserves. Repeatedly reducing application engineering, software support and customer knowledge may protect current earnings while weakening the next product generation. Long-term projects require milestones and accountability, but they also require continuity.

    Europe’s strongest opportunity is to connect its existing expertise with the realities of occupied buildings. That involves partnerships with electrical, automation and building-service businesses; clearer responsibility for commissioning and maintenance; and products designed to remain useful within evolving systems.

    Traditional lighting manufacturers still have substantial advantages in optical performance, specification and application knowledge. New entrants have their own execution gaps. The eventual outcome is open.

    What should concern established leaders is the possibility of remaining technically capable while becoming commercially secondary—supplying devices into systems whose customer relationships and service revenues belong to someone else.

    The next generation of European lighting leadership will be earned through products and services that people can recognise as better, supported by investment that produces durable returns. The question for today’s leaders is whether their current decisions are building that future.

    Sources and reading notes

    The references distinguish company financial reports, product announcements and secondary scale estimates. Product and investment announcements establish actions or intentions, not proven financial returns. Figures retain their original currencies and reporting periods; group, brand, legal-entity and product-line disclosures are not interchangeable.

    For readers using a platform that does not support external links, copy the full address below into a browser. Some financial-report links open PDFs; long addresses should be copied in full.

    [1] EU Energy Performance of Buildings Directive
    Regulatory context for technical building systems; implementation and scope depend on the relevant provisions.
    https://eur-lex.europa.eu/eli/dir/2024/1275/oj

    [2] Signify reporting and announcements
    Company reporting archive; annual results supply the historical group figures.
    https://www.signify.com/global/our-company/news/press-releases

    [3] Signify: CEO appointment
    Background and timing of As Tempelman’s appointment.
    https://www.signify.com/global/our-company/news/press-releases/2025/20250528-signify-names-as-tempelman-as-chief-executive-officer

    [4] Zumtobel Group corporate information
    Company reporting and announcements; group and segment measures must be distinguished.
    https://z.lighting/en/group/investor-relations/

    [5] Zumtobel: Heiner Lang appointment
    Board entry and planned CEO succession dates.
    https://z.lighting/en-gb/group/news-insights/ir/supervisory-board-appoints-heiner-lang-ceo-zumtobel-group/

    [6] Zumtobel Q1 FY2026/27 results
    Quarterly figures preceding the incoming CEO’s tenure.
    https://z.lighting/documents/4085/Zumtobel_Group_-Press_releases-_Q1_2026-27.pdf

    [7] Fagerhult investor information
    Annual reporting, portfolio and acquisition information.
    https://www.fagerhultgroup.com/investors/

    [8] Luceco investor information
    Group reporting includes electrical products beyond lighting.
    https://www.lucecoplc.com/investors/

    [9] F.W. Thorpe annual report 2025
    Financial results, SmartScan and operating model.
    https://www.fwthorpe.co.uk/pdf/fw-thorpe-annual-report-2025.pdf

    [10] TRILUX company profile, DDW
    Secondary historical revenue estimate for 2023.
    https://die-deutsche-wirtschaft.de/unternehmen/trilux-gmbh-co-kg-arnsberg/

    [11] TRILUX sustainability report 2023/24
    Polish facility investment and capacity; pages 36–37.
    https://www.trilux.com/fileadmin/Downloads/Documents/Nachhaltigkeit/Sustainability_Report_2023-2024.pdf

    [12] TRILUX Arnsberg investment announcement
    Planned investment over three years, announced July 2026.
    https://www.trilux.com/de/blog/neubau-standort-arnsberg/

    [13] TRILUX Retail integration
    Brand and organisational changes.
    https://www.trilux.com/ch/blog/trilux-retail-migration/

    [14] nnuks sustainability report 2022
    Historical 2021 multi-brand group turnover.
    https://slv-lighting-group.com/wp-content/uploads/2022/06/NKS_BRO_Sustainability-2022_210x279.pdf

    [15] SLV Lighting Group sustainability report 2025
    Brand portfolio and procurement, logistics and sales integration; pages 8–11.
    https://a.storyblok.com/f/113144/x/f85bebdba1/slg_bro_sustainability-2025_210x279mm_72dpi.pdf

    [16] ERCO new products
    Application and product information; not financial evidence.
    https://www.erco.com/en/products/new-products/

    [17] ERCO business-index profile
    Secondary legal-entity figure with an unclear consolidation boundary.
    https://www.weltmarktfuehrerindex.de/profil/erco

    [18] FLOS S.p.A. company-account summary
    Secondary transcription of legal-entity accounts, not global brand revenue.
    https://www.reportaziende.it/flos_societa_per_azioni_bs_00290820174

    [19] FLOS at Milan Design Week 2026
    Product-development evidence.
    https://flos.com/en/wo/flos-at-milano-design-week-2026.html

    [20] Flos B&B Italia Group H1 2026 presentation
    Continuing-business pro forma results, pages 5 and 12; includes non-lighting businesses.
    https://www.flosbebitaliagroup.com/on/demandware.static/-/Library-Sites-DHCorp-contentlib/default/dw8ee7cc40/Investors/Reports%20and%20publications/1_presentation_Flos%20B%26B%20Italia%20S.p.A.%20-%20H1%202026_last.pdf

    [21] Louis Poulsen transaction: buyer’s adviser
    Announced transaction subject to completion conditions.
    https://accura.dk/en/cases/chr-augustinus-fabrikker-acquires-louis-poulsen/

    [22] EGLO official company profile
    Self-reported 2024 scale; no matching profit or cash-flow disclosure.
    https://lu.linkedin.com/company/eglo-leuchten-gmbh

    [23] GLX Holding preliminary 2025 results
    Holding-company reporting scope and preliminary results.
    https://www.glamox.com/news-and-stories/glx-holding-as-the-holding-company-of-glamox-closes-2025-with-improved-profitability-and-robust-performance/

    [24] EY profile of Schréder
    Historical 2023 turnover, published December 2024.
    https://www.ey.com/en_be/newsroom/2024/12/schreder-named-l-entreprise-de-l-annee-2024

    [25] Schréder acquisition of NLS Lighting
    Announced April 2026; price not disclosed.
    https://www.schreder.com/en/news/schreder-announces-acquisition-nls-lighting

    [26] Plejd year-end report 2025
    Reported growth, profitability and management explanation of organic expansion.
    https://news.cision.com/plejd/r/year-end-report-2025,c4296913

    [27] Dexelance investor presentation, April 2026
    Lighting-segment revenue, page 25.
    https://dexelance.com/wp-content/uploads/Investor-Presentation-DEXELANCE_v.-08.04.2026-FINAL-1.pdf

    [28] Edison research on Dialight
    Company-commissioned external research; group and lighting-segment results on pages 3–4.
    https://static.lse.co.uk/research/download/3653.pdf

    [29] MLS annual report 2025
    Listed parent’s product-line and acquisition-accounting disclosures, in Chinese.
    https://money.finance.sina.com.cn/corp/view/vCB_AllBulletinDetail.php?id=12234150&stockid=002745

    [30] MLS interim report 2026
    Product-line gross profit and consolidated group results, in Chinese.
    https://money.finance.sina.com.cn/corp/view/vCB_AllBulletinDetail.php?id=12563625&stockid=002745

    [31] LEDVANCE management announcement, August 2026
    Management responsibilities and European operating priorities.
    https://www.ledvance.com/en-uk/company/press/press-releases/2026/ledvance-strengthens-its-management-team-with-dr-markus-emmert-n479050

    [32] LEDVANCE Renewables announcement
    Product range and stated strategy, not separate financial results.
    https://www.ledvance.com/en-int/company/press/press-releases/2024/ledvance-introduces-ledvance-renewables–photovoltaics-for-a-brighter–greener-future-n303994

    [33] IKEA FY2025 retail sales
    Worldwide retail-system figures, not lighting-segment results.
    https://www.ikea.com/global/en/newsroom/corporate/ikea-retail-sales-fy25-251016/

    [34] IKEA smart-home product announcement
    November 2025 Matter-compatible range.
    https://www.ikea.com/global/en/newsroom/retail/the-new-smart-home-from-ikea-matter-compatible-251106/

    [35] Kingfisher annual report 2025/26
    Group and B&Q financial results; fiscal year ended January 2026.
    https://www.kingfisher.com/~/media/Files/K/Kingfisher-Plc/Universal/investors/result-reports-presentation/2026/2526-annual-report-and-accounts.pdf

    [36] Kingfisher own exclusive brands
    43% relates to group sales across categories, not lighting alone.
    https://www.kingfisher.com/our-banners-and-brands/own-exclusive-brands

    [37] Kingfisher Q1 2026/27 update
    Quarter ended April 2026; separate period from annual results.
    https://www.kingfisher.com/~/media/Files/K/Kingfisher-Plc/Universal/investors/result-reports-presentation/2026/2026-27-q1-trading-update.pdf

    [38] Inventronics annual reporting and acquisition information
    Company disclosures concerning acquired operations and subsequent performance; source in Chinese.
    https://cn.inventronics-co.com/news_info/33/1771.html

    [39] Signify strategy announcement, June 2026
    Medium-term growth, profitability and cash-flow targets are management objectives, not reported outcomes.
    https://www.signify.com/global/our-company/news/press-releases/2026/20260623-signify-introduces-strategy-to-create-a-more-focused-better-performing-company

  • Understanding Light 13 | The 18-Part Series on Healthy Lighting / Comprehensive Lighting Basics

    September 14, 2026

    “Blue Light”: Risk, Circadian Signal, or Marketing Buzzword?

    Behind the same term are actually three completely different questions.

    Author | Lawrence Lin

    Chairman, GLGA | Board Member, GLG | IWBI WELL Light Concept Advisor | Founder & CEO, LRS

    Consumers sometimes ask me about “blue-light protection” lighting: “If blue light is harmful, why do we also want to increase melanopic stimulation during the day?” This is not a contradiction. Rather, the industry has long used the single term “blue light” to describe three different concepts.

    Blue-light hazard, circadian-related stimulation, and visual fatigue need to be discussed separately. Their wavelength ranges may overlap, but their mechanisms, doses, evaluation methods, and risk contexts are different.

    Blue-Light Hazard: Photochemical Retinal Damage

    The blue-light hazard defined by CIE specifically refers to the risk of photochemical retinal injury, evaluated using the relevant hazard weighting function together with radiance/irradiance. It is not the same as an effect on sleep, nor is it the same as “feeling tired from looking at a screen.”

    Under foreseeable normal-use conditions, ordinary white-light illumination generally does not constitute a blue-light hazard.

    High-intensity specialized light sources, close-range viewing, or specific industrial environments still need to be evaluated according to requirements such as IEC 62471. The above conclusion should not be used to rule out every situation.

    Circadian-Related Stimulation: Timing and Exposure Matter

    The melanopsin pathway is relatively sensitive to short-wavelength visible light, but it should be described using the melanopic metrics defined in CIE S 026, rather than simply saying that there is “more blue light.”

    Appropriate light exposure during the day and reduced exposure at night are time-based strategies. They should not be substituted with blue-light-hazard classifications.

    Likewise, reducing the impact of screens at night is not simply a matter of putting a yellow filter over the display. Brightness, viewing distance, exposure duration, psychologically stimulating content, and the lighting of the entire room all matter.

    Visual Fatigue: Often Not a Wavelength Problem

    Dry eyes, reduced blinking, text that is too small, reflective glare, prolonged close-up viewing, and posture can all contribute to discomfort.

    Blaming all visual fatigue on blue light can cause genuinely effective interventions to be overlooked.

    A responsible “low-blue-light” product should explain which part of the spectrum has been reduced, what color performance has been sacrificed, which time periods the product is intended for, and which testing methods support the claim.

    What We Can Say Today / What We Cannot Yet Say

    What we can say today: Blue-light hazard has a specific photobiological safety definition; melanopic stimulation has its own measurement framework; and visual fatigue is a multifactorial issue.

    What we cannot say: Blue light in ordinary white-light illumination necessarily damages the retina, or that removing blue light automatically solves sleep problems or visual fatigue.

    Three Things You Can Do Today

    • When you hear the term “blue light,” first ask whether the discussion concerns photobiological safety, circadian effects, or visual comfort.
    • For specialized high-intensity light sources, use the IEC 62471 series for risk classification rather than substituting a marketing label.
    • At night, prioritize reducing overall brightness and exposure duration, and then optimize the spectrum.

    Evidence label: Established consensus.
    These three questions should be measured and communicated separately.

    References

    • CIE Position Statement on Blue Light Hazard ：https://cie.co.at/publications/position-statement-blue-light-hazard-april-23-2019
    • IEC 62471-7:2023 ：https://webstore.iec.ch/en/publication/68810
    • CIE S 026:2018 ：https://www.cie.co.at/publications/cie-system-metrology-optical-radiation-iprgc-influenced-responses-light-0

    In the next article, we look at another issue often dismissed with the phrase “flicker-free”: Why can invisible flicker still affect lighting quality?

  • Understanding Light 12 | The 18-Part Series on Healthy Lighting / Comprehensive Lighting Basics

    September 11, 2026

    Full-Spectrum Does Not Equal Healthy, and Color Temperature Is Not a Cure-All

    Bringing the spectrum back to measurable characteristics instead of asking it to carry promises beyond the evidence

    Author | Lawrence Lin

    Chairman, GLGA | Board Member, GLG | IWBI WELL Light Concept Advisor | Founder & CEO, LRS

    “We use a full-spectrum light source, so it’s better for your eyes, helps you sleep, and is closer to natural daylight.” This kind of marketing language is common. “Full spectrum” sounds complete and natural, which makes it particularly easy to attach claims that go beyond the available evidence.

    At present, “full spectrum” is not a standardized prescription that automatically corresponds to specific health outcomes in market communications. To evaluate a light spectrum, we should return to specific measurable metrics: color rendering, gamut, distribution across specific wavelength bands, mel-DER, and overall performance under different operating conditions.

    Continuous Does Not Mean Suitable for Every Time of Day

    A seemingly continuous and smooth spectrum may provide a pleasant color experience, but whether it is appropriate for a morning office, an evening residence, or museum display still depends on quantity, direction, timing, and the people exposed to it.

    Daylight itself is not a fixed spectral curve. It changes with weather, time of day, orientation, and sky conditions.

    Without specifying the conditions of comparison, saying that a light source is “like daylight” is difficult to turn into a rigorous conclusion. Moreover, the goal before bedtime is not to reproduce midday sunlight, but to reduce unnecessary light exposure.

    CCT Cannot Replace the Spectrum

    Two 3000 K light sources can have different levels of color fidelity, gamut, and mel-DER.

    Conversely, a 4000 K product that has been appropriately dimmed may result in lower mel-EDI at the eyes than an undimmed 2700 K product.

    Color temperature affects color appearance and atmosphere, but it is not a physiological dose.

    Color quality should also not be evaluated solely through the general color rendering index Ra. CIE has recommended that, during the transition period, CIE Rf and Ra be reported together. If a project is concerned with color preference and colorfulness, more complete gamut and hue information is also needed.

    What Should You Ask When Comparing Products?

    Request machine-readable spectral data, rather than just images or marketing graphics.

    Confirm that the data correspond to the specified power level, color temperature, and dimming setting.

    Check whether color fidelity, gamut, mel-DER, efficiency, and temporal light modulation are all acceptable at the same time.

    If a supplier claims that a product improves sleep or cognition, ask about the population studied, the exposure scenario, and the duration of the human study.

    A truly professional product is not afraid to clearly state its boundaries.

    What We Can Say Today / What We Cannot Yet Say

    What we can say today: The shape of the spectrum affects color appearance and α-opic stimulation; complete spectral data have greater engineering value than a “full-spectrum” label.

    What we cannot say: A continuous spectrum, a CCT close to daylight, or a high Ra value automatically means that a product is better for the eyes, improves sleep, or is suitable for all-day use.

    Three Things You Can Do Today

    • Replace the term “full spectrum” with verifiable spectral, color, and α-opic metrics.
    • When comparing dimmable and tunable products, evaluate every critical scenario, rather than only the rated operating condition.
    • When communicating with consumers, clearly distinguish between “natural appearance / accurate color” and “medical or health outcomes.”

    Evidence label: Established consensus / Open question.
    The spectrum can be accurately measured; there is no automatic equivalence between a single market label and long-term health outcomes.

    References

    • CIE PS 002:2025 ：https://www.cie.co.at/publications/cie-ps-0022025-cie-position-statement-colour-quality-metrics-2nd-edition
    • CIE S 026:2018 ：https://www.cie.co.at/publications/cie-system-metrology-optical-radiation-iprgc-influenced-responses-light-0
    • CIE 253:2024 — Technical Reports ：https://cie.co.at/publications/technical-reports

    In the next article, we continue unpacking another term that easily triggers anxiety: Is blue light actually a risk, a circadian signal, or simply a marketing buzzword?

  • Understanding Light 11 | The 18-Part Series on Healthy Lighting / Comprehensive Lighting Basics

    September 9, 2026

    Integrated Lighting Must First and Foremost Be Good Lighting

    Without visual quality, no health-related objective can stand on solid ground.

    Author | Lawrence Lin

    Chairman, GLGA | Board Member, GLG | IWBI WELL Light Concept Advisor | Founder & CEO, LRS

    An office once added a very bright luminous surface directly in front of employees in an effort to increase light exposure at the eyes. The measured numbers looked excellent, but employees began wearing hats, turning off the lights, and even blocking the light with cardboard. The design achieved its calculated target—but lost its users.

    Integrated lighting is not about adding another number on top of conventional lighting. It must first satisfy visibility, comfort, safety, and spatial quality, and only then address appropriately timed non-visual stimulation. A lighting scheme that people actively try to escape from is unlikely to deliver its intended benefits over the long term.

    The Non-Negotiable Foundations of Good Lighting

    Illuminance should be appropriate to the task, and its distribution should not force the eyes to repeatedly adapt between extremely bright and extremely dark areas. Glare must be controlled, and screens and glossy surfaces should not produce distracting reflections. Color rendering should support the recognition of people, materials, and warning information. Temporal light modulation should not create noticeable flicker or stroboscopic effects.

    The space also needs hierarchy. Uniformity does not mean making every surface equally bright, and dynamic lighting does not mean changing the color temperature every ten minutes. Human attention, orientation, and the atmosphere of a space often come from orderly relationships between different luminance levels.

    The Metrics Need to Be Balanced

    Increasing vertical illuminance may increase glare; increasing wall luminance may increase energy consumption; changing the spectrum may affect color rendering and system efficiency; excessive dimming may amplify temporal light modulation from certain drivers.

    The value of engineering design lies precisely in finding the overall optimum within these constraints, rather than pursuing a single metric as the “champion.”

    This is also the full meaning of what CIE describes as “proper light at the proper time”: the right light is not defined only by quantity and timing, but also by quality and the environment in which it is used.

    User Behavior Is One of the Final Judges

    If users frequently pull the curtains, disable automatic controls, or block luminaires, the first step should be to understand why.

    Glare, temperature, privacy, screen reflections, or control logic can all cause the original design intent to fail. Post-occupancy feedback is not a soft bonus—it is evidence of whether the system actually works.

    What We Can Say Today / What We Cannot Yet Say

    What we can say today: Integrated lighting should simultaneously address visual comfort, task performance, safety, circadian-related objectives, energy, and building conditions.

    What we cannot say: Achieving a particular melanopic value justifies sacrificing glare control, color rendering, flicker control, or user autonomy.

    Three Things You Can Do Today

    • Establish a combined checklist covering illuminance, glare, color rendering, temporal light modulation, controls, and mel-EDI.
    • During mock-up testing, have real users sit, look, and perform tasks—not just let instruments take measurements.
    • After acceptance, conduct a follow-up and observe “anti-design behaviors” such as blocking lights, turning lights off, or pulling curtains.

    Evidence label: Established consensus.
    The foundation of integrated lighting is meeting the requirements of overall lighting quality.

    References

    • CIE PS 001:2024: https://cie.co.at/publications/cie-position-statement-integrative-lighting-recommending-proper-light-proper-time-3rd
    • ISO/CIE 8995-1:2025: https://www.iso.org/standard/76342.html
    • GB/T 50034—2024 Publication Information: https://sczjjgfw.gov.cn/clas/wjhb/jsb/24/jsb202433.html

    In the next article, we tackle one of the loudest terms in the market: Why doesn’t “full spectrum” automatically mean healthy, and why isn’t color temperature a cure-all?