A distributor building a 2027 catalogue has two questions in front of them, and they are not the same question. The first is what to stock. The second is what to promise. Light quality and connected control are the two directions that will shape both answers, but they arrive at the warehouse very differently: one is a documentation problem, the other is a certification problem.
This guide treats them that way. On light quality, the standards material behind glare, spectrum and circadian metrics shows that a single datasheet number is a weaker commitment than most catalogues imply. On control, the DALI Alliance’s own certification records show where interoperability is independently tested and where it is still self-declared or emerging. Where the evidence is a standard, a certification programme or a first-party announcement, it is described as such. Where the conclusion is a procurement judgment rather than a sourced fact, it is labelled.
No market-size forecasts appear here. The useful preparation for 2027 is not a growth figure; it is knowing which claims you can defend to a specifier and which SKUs carry the most risk if you cannot.
What’s Actually Changing in the 2027 Buying Cycle
The clearest signal on the light-quality side is a shift in where the burden of proof sits. The ZVEI method paper on UGR opens with a statement that should reframe how you read a cut sheet: glare is a property of a lighting installation, not of an individual luminaire. A single UGR data sheet value describes a luminaire only inside its special standard room with defined properties; in practice the value can differ significantly and serves as an approximation for the planner.
EU Ecodesign Regulation (EU) 2019/2020 temporal light modulation limits for LED and OLED light sources operated on mains voltage at full load. The IEA 4E report finds headroom for tighter limits but does not announce any; it is silent on dimmed operation, so these values do not describe performance at dimmed levels.
That is a standards document talking about its own method, not a competitor criticising a rival. It means the “UGR < 19” line in a catalogue is a starting point for a lighting design, not a guarantee about a finished office.
Flicker is moving in the opposite direction — from unregulated to regulated to possibly tighter. The IEA 4E SSLC Platform’s analysis of temporal light modulation across 2014–2025 records that the EU Ecodesign Regulation (EU) 2019/2020 set limits from 1 September 2021 of 1.0 for PstLM and 0.9 for SVM, with the SVM maximum dropping to 0.4 from 1 September 2024. The regulation applies to LED and OLED light sources operated on mains voltage at full load. The report’s own conclusion is that current PstLM and SVM requirements could be set to a more ambitious level without an identified impact on product availability.
Read that carefully: the report finds headroom for tighter limits. It does not announce new limits, and it does not tell you what any future value will be. For a distributor, the practical content is that PstLM and SVM are now numbers a supplier can be asked to publish, and that the EU baseline is a floor rather than a ceiling.
On the control side, the evidence is about certification maturity rather than sales. The DALI Alliance ended registration of DALI version-1 control gear and now points buyers to the DALI-2 and D4i logos as confirmation of third-party-certified compliance. DALI+ with Thread has moved from specification to certified product, and the Alliance has introduced testing and certification specifications for wireless-to-DALI gateways that translate between DALI systems and Bluetooth NLC and Zigbee. None of that is a volume forecast. It is a map of what is certified, by whom, and against what.
Trend 1: Light Quality Moves from Datasheet Number to Installation Question
For a distributor, the light-quality trend compresses into one operational change: customers will increasingly ask for the file behind the number. That is a service question as much as a product question, and it favours suppliers who can hand over photometric data and design support rather than a single figure on a line card.
Consensus melanopic EDI targets by time of day, adopted by the Society of Light and Lighting from Brown et al. (2022) and endorsed in CIE PS 001:2024. Values are vertical at eye level for healthy day-active adults; the daytime figure is a condition to sustain across occupied hours, not a brief daily dose, and the SLL states the evidence is not yet sufficient to prescribe universal design formulae. Not a product rating.
Glare: What a UGR Value Can and Cannot Promise
The UGR scale runs from 10 to 30, with higher values indicating greater discomfort, and a UGR of 19 is commonly treated as the upper limit of acceptable discomfort glare. That convention is widely repeated, but the method behind it has boundaries worth knowing before you quote it.
First, the tabular method — the source of the single value or grid on a spec sheet — is limited to room dimensions between 2H and 12H, where H is the luminaire height above the observer’s eye. Below 2H, discomfort glare is unlikely; above 12H, DIN EN 12464-1:2021 allows 12H to be assumed as a representative value. Second, the tabular values are averages over different viewing directions, so there may be positions in a room where an individual luminaire causes more glare than the table suggests.
Third, and most important for catalogue language, UGR values are meant to be compared by classification band, not by decimal. The DIN EN 12464-1 sequence is 16, 19, 22, 25, 28. Two luminaires at 19.8 and 21.2 both fall in the ≤ 22 group and are classified equally; two at 19.1 and 19.6 fall into different groups (≤ 19 and ≤ 22). The ZVEI paper states plainly that a numerical comparison to one decimal place is not intended and does not by itself establish that one product is better or worse.
Two further limits matter when a customer pushes back. The UGR method cannot evaluate disability glare — glare that reduces visual function without necessarily causing discomfort — so a UGR figure says nothing about that effect. And a single number does not represent all configurations of a product: UGR varies with a luminaire’s lumen output, colour temperature, lens options, finish and light distribution, so a value quoted for one build should not be assumed to hold across the family.
The stocking implication is not that UGR values are useless. It is that the defensible sales position is “here is the photometric file and the design support to confirm compliance in your room,” not “our product is UGR 19.” Distributors who can supply the first will win the specification conversation; those who repeat the second inherit the risk.
Full-Spectrum and Colour Quality: Beyond a Marketing Label
The DOE’s LED colour characteristics fact sheet explains why colour claims need care. Chromaticity and correlated colour temperature are simplifications of the spectral power distribution, built on models of human vision developed for a specific field of view. Two sources with the same chromaticity coordinates can still appear different under other conditions or to individual observers.
Nominal CCT is looser still. A designation such as 3000 K or 4000 K covers a range of actual CCT and Duv values as defined in ANSI C78.377-2015, and two sources with the same nominal CCT can appear very different. Specifying only a nominal CCT does little to ensure that products from different batches or suppliers will look alike.
CRI carries acknowledged limitations of its own. The DOE fact sheet notes that the CIE has recognised the limits of the CIE Test-Color Method, and that reliance on average colour fidelity provides little benefit for selecting the best source for an application — sources optimised for the eight Ra samples do not necessarily render a broader range of colours well. ANSI/IES TM-30-20 provides a newer framework with colour fidelity (Rf) and gamut (Rg) measures, and its annex material shows that criteria based on Ra alone, or on Ra plus R9, are not effective for predicting colour preference.
“Full-spectrum” is not a standardised pass/fail label in any of this material. It is a marketing term without a defined test. The actionable ask is spectral power distribution data and colour-rendering metrics reported to a named method — Ra with R9 at minimum, and Rf/Rg where a specifier is working to TM-30 — so the customer can judge the product against their own criteria.
Circadian and Melanopic Specifications: Tender-Ready or Not Yet?
The CIBSE/SLL position statement on integrative lighting is explicit about its own status: it is a position statement, not a design standard, and practitioners should use it to inform professional judgement, avoid over-claiming, and distinguish established principles from emerging evidence and open research questions.
What is established is the measurement framework. CIE S 026:2018 defines melanopic equivalent daylight illuminance (melanopic EDI) as the recommended quantity for describing the direct photic stimulus to the ipRGCs, replacing informal references to “melanopic lux,” and the CIE recommends assessing light at the observer’s eye plane rather than the horizontal task plane. The SLL statement adopts the Brown et al. (2022) targets as set out in CIE TN 015:2023 and endorsed in CIE PS 001:2024: daytime ≥ 250 lx melanopic EDI, evening (three hours before sleep) ≤ 10 lx, and night ≤ 1 lx.
The SLL is careful about how those targets should be used. The daytime recommendation should not be treated as a brief daily dose unless that interpretation is explicitly justified by evidence, and the evidence is not yet sufficient to prescribe universal design formulae across all populations, buildings and schedules. The central organising principle the statement endorses is “bright days, dark nights,” with daylight as the primary source of daytime melanopic exposure and electric lighting as a complementary tool.
Certification schemes do specify thresholds. WELL’s circadian lighting design feature sets a minimum daytime light intensity, measured as equivalent melanopic lux on the vertical plane at eye level during performance verification, with a worked example for education settings of at least 125 EML at 75% or more of desks for at least four hours per day. That is one scheme’s requirement, not an industry-wide standard.
Whether circadian specifications appear in your customers’ tenders is a judgment, and it will vary by project type and region. Where a client is pursuing a named certification or has a specialist lighting designer on the team, expect melanopic language. Where the project is a straightforward fit-out, expect it rarely. The stocking conclusion follows from that: hold tunable or melanopic-capable product where a scheme or client actually specifies it, and treat speculative depth in that category as a bet rather than a hedge.
Trend 2: Connected Control — DALI, Matter and Sensing in the Same Conversation
DALI and Matter are often discussed as if they were competing answers to the same question. They are not. DALI is a lighting-specific control protocol built on the international IEC 62386 standard and administered through the DALI Alliance’s certification programmes. Matter is a device interoperability standard from CSA-IoT, positioned around smart-home and cross-ecosystem compatibility, with lighting and electrical listed among its supported device categories.
That difference in scope is what makes the “does Matter replace DALI” question answerable, and the answer matters for what you stock.
DALI-2, D4i and DALI+: What Certification Actually Delivers
The distinction between DALI version-1 and DALI-2 is the distinction between self-declaration and third-party verification. The DALI Alliance’s own announcement records that DALI version-1 testing was less detailed and relied on self-declaration without third-party verification, while DALI-2 certification requires rigorous product testing with results independently verified by the Alliance. The Alliance has since ended registration of DALI version-1 control gear and directs users to the DALI-2 or D4i logos as confirmation of certified compliance.
D4i is an extension of DALI-2 with a mandatory feature set. The Alliance specifies DALI Part 251 (luminaire data), Part 252 (energy data) and Part 253 (diagnostics data) as mandatory, along with Part 250 (integrated bus power supply); Part 150 (AUX power supply) is optional. In practice, that means a D4i driver stores luminaire information — colour temperature, optical distribution — that can be extracted at commissioning and used for asset management, and reports real-time energy use and diagnostics that support preventive maintenance.
DALI+ extends the same DALI language, features and data over wireless and IP-based networks, with DALI+ with Thread certified products now on the market. The Alliance describes DALI+ as able to expand existing DALI installations rather than replace them, and positions it for retrofits and hybrid wired-wireless projects. A new certification programme for wireless-to-DALI gateways addresses the translation layer between DALI systems and Bluetooth NLC and Zigbee.
For a distributor, the value is narrower and more concrete than the technology story. Certified product reduces the interoperability risk you carry when a contractor mixes your driver with someone else’s controller. The D4i data set reduces the service friction at replacement time, because the luminaire’s identity and history travel with the driver rather than living in a commissioning file nobody can find.
Does Matter Replace DALI in Commercial Projects?
On the sourced material, no — the evidence supports coexistence and bridging, not replacement.
Matter’s own documentation describes it as making devices compatible with smart-home and voice ecosystems, running on Wi-Fi and Thread network layers with Bluetooth Low Energy for commissioning, and supporting bridges so that devices using other protocols can participate in a Matter ecosystem. That is an interoperability layer aimed at cross-ecosystem consumer and light-commercial convenience.
The DALI Alliance’s material describes DALI+ and the new wireless-to-DALI gateway certification as bridges between DALI systems and wireless protocols including Bluetooth NLC and Zigbee. Both ecosystems, in other words, are building the same kind of connective tissue — which is what coexistence looks like in practice.
What the sources do not establish is how large a role Matter will play in commercial project specifications. That is a judgment to confirm with the specifiers you actually sell to, not a fact either organisation’s material settles. Ask your project customers what their controls consultant is writing before you commit stock depth to any single wireless ecosystem.
Sensors and Luminaire-Level Control: The Stock-Keeping Question
The DALI Alliance describes D4i as designed to enable luminaire-level lighting control, with power requirements that allow plug-and-play connectivity of luminaires, network lighting controllers and sensors, particularly when used with a connector system such as Zhaga or ANSI C136.41. By handling the power requirements for luminaire-mounted controllers and sensors, D4i reduces component count and simplifies wiring inside the luminaire.
The Alliance notes that D4i is already well established in outdoor and industrial lighting, where the data is particularly valuable, and that indoor applications are emerging.
For stock-keeping, sensor-ready luminaires change the spare-parts picture in two ways. First, the sensor or controller becomes a separate line item with its own compatibility requirements, so a replacement is not simply “the same fitting again.” Second, the D4i data set becomes the record of what was installed — which matters most at the moment a building changes hands or a maintenance contractor inherits a site with no documentation. Distributors who can supply the matching sensor and read the driver’s stored data are solving a service problem, not just filling a shelf.
Where the Inventory Risk Sits
The following is procurement reasoning from distributor economics, not sourced market data. It maps each trend to the type of risk it creates, because the risks are not interchangeable and should not be managed with the same inventory rule.
Glare and quality claims. The risk is over-promising. If your catalogue repeats a single UGR value as a product guarantee, and the installed result differs — as the method’s own documentation says it can — the dispute lands on you, not the manufacturer. The exposure is reputational and contractual rather than purely financial, and it is cheapest to avoid by changing what you publish.
Circadian and melanopic product. The risk is stocking ahead of confirmed demand. The measurement framework is settled; the tender uptake is not. Depth in tunable or melanopic-capable families is a bet on your specific customer base, and it should be sized against named projects or certification-driven clients rather than against the general direction of the market.
DALI-2 and D4i. The risk is mixed inventory. Legacy DALI version-1 stock sits alongside certified DALI-2 product, and the two look similar on a shelf and read similarly on a short spec. The Alliance has ended version-1 registration and points buyers to the logos, which means the older stock is harder to defend in a specification conversation even where it still works. The other exposure is a certification mismatch: a driver certified to DALI-2 but without the D4i data parts will not deliver the asset-management and diagnostics functions a customer was promised.
DALI+ and Matter. The risk is early-standard churn and gateway compatibility. DALI+ with Thread is certified and shipping, and wireless-to-DALI gateway certification is new. Both are moving. Committing deep stock to a single wireless configuration before your project customers have settled on their controls architecture leaves you exposed to a revision you cannot control.
What this reasoning does not support is any statement about when older product becomes obsolete. No source here establishes obsolescence dates, and inventing one would be worse than leaving the question open. The honest position is that version-1 stock carries a documentation disadvantage today and an unknown resale horizon, and that the right response is to manage its depth rather than to declare it dead.
A Supplier Question Checklist for 2027 Line Reviews
These are questions to put to suppliers during a 2027 line review. They are framed as requests for evidence, not as claims about any supplier’s current documentation — the point is to find out what a supplier can actually produce before you commit shelf space.
On glare
- Can you provide the photometric file (IES/LDT) for this product, not only a UGR value?
- Is the published UGR figure a single data sheet value or a full UGR table, and under what standard room assumptions was it generated?
- Does the value hold across the configurations we intend to stock — different lumen outputs, colour temperatures, lens options and distributions?
- Can you support installation-level glare assessment for a specific project, or point to design support that can?
On flicker
- What are the PstLM and SVM values for this product, and at what dimming level were they measured?
- Do you have test data across the full dimming range, not only at full output?
- Which regulatory scope do the reported values address? The EU Ecodesign limits of PstLM 1.0 and SVM 0.4 (from 1 September 2024) apply to mains-voltage LED and OLED light sources at full load, so a value reported against them tells you about that condition specifically.
On colour quality
- Can you supply the spectral power distribution for the exact build we are buying?
- What are the Ra and R9 values, and is Rf/Rg reported to TM-30 as well?
- What CCT and Duv binning do you apply, and to which standard?
On DALI and D4i
- Is this product DALI-2 certified, and can you show the certification listing?
- If it is offered as D4i, are Parts 251, 252 and 253 implemented, and is Part 250 integrated bus power supply present?
- Which connector system does the sensor interface use — Zhaga, ANSI C136.41, or a proprietary arrangement?
On DALI+, Matter and gateways
- For DALI+ product, which carrier is certified — Thread specifically — and can you show the certification?
- For any gateway, is it covered by the DALI Alliance’s wireless-to-DALI gateway certification, and which wireless protocols does it translate?
- If Matter is claimed, what interoperability documentation exists, and which ecosystem platforms has it been tested against?
A supplier who can answer the first question in each group is worth a longer conversation. A supplier who can answer all of them has done the work you would otherwise have to do after the sale.
What to Add, Keep and De-emphasize
The temptation in a trend article is to produce a universal list of what to buy. That list would be invented. What follows is professional reasoning from distributor economics — decision criteria you can apply to your own customer base, not sourced market data.
Four criteria, applied to both trends
- Confirmed project specification. Is a named customer or project actually asking for this, in writing?
- Certification evidence. Can the supplier produce a listing, a test report or a certified data set, rather than a claim?
- Service and spares availability. Can you supply the matching sensor, driver or gateway when one fails in year three?
- Regional regulatory scope. Does the requirement you are stocking against actually apply in the market you sell into?
Light quality
Add: product families where the supplier can hand over photometric files, SPD data and flicker metrics as standard. This is a documentation capability as much as a product one, and it is the cheapest way to defend a specification.
Keep: core commercial families with solid, well-documented colour quality — Ra and R9 reported, CCT and Duv binned to a named standard. These remain the volume business.
De-emphasize: catalogue language that turns a single UGR value or the word “full-spectrum” into a headline claim. The product may be perfectly good; the claim is what creates the exposure. Where a customer needs a glare commitment, route it through design support rather than a datasheet number.
Hold conditionally: tunable and melanopic-capable families, sized to confirmed certification-driven or specialist-design projects rather than to the general direction of the market.
Connected control
Add: DALI-2 certified drivers and control devices, and D4i product where the customer’s project involves asset management, energy reporting or luminaire-level control. The certification is independently verified and the data set has a service life beyond installation.
Keep: DALI-2 product across the common control gear types, including colour control and self-contained emergency, which the Alliance lists as covered by the programme.
De-emphasize: DALI version-1 stock as a forward-looking line. It still works and it still sells into existing installations, but it carries a documentation disadvantage in new specifications and an unknown resale horizon. Manage its depth rather than its existence.
Hold conditionally: DALI+ with Thread and Matter-compatible product, scaled to projects where the controls architecture is already decided. Both are certified and both are moving; neither is a reason to build depth ahead of demand.
Conclusion
The 2027 buying cycle rewards a specific and unglamorous skill: reading the scope of a standard and the provenance of a certification. A UGR value, a CCT, a “full-spectrum” claim and a control protocol logo all look like settled facts on a line card. Most of them are conditional, and the conditions are where the margin and the risk both live.
On light quality, the direction is toward installation-level questions. Glare is a property of a room, not a fitting; colour is a spectral distribution, not a label; circadian metrics have a rigorous measurement framework but not yet universal design formulae. Distributors who can supply the file, the spectrum and the test data will hold the specification conversation. Those who repeat the headline number will inherit the dispute.
On connected control, the direction is toward certified interoperability and coexistence. DALI-2 and D4i deliver independently verified compliance and a data set that outlives the installation. DALI+ extends the same language over wireless and IP networks, and the new gateway certification connects DALI systems to Bluetooth NLC and Zigbee. Matter, on the sourced material, sits alongside rather than replaces any of it — an interoperability layer aimed at cross-ecosystem convenience, whose commercial-project role is a question for your specifiers.
The checklist in this guide is the reusable part. Run it at every line review, keep the answers on file, and the 2027 catalogue becomes a set of defensible commitments rather than a set of claims you hope nobody tests.
FAQ
Does Matter replace DALI in commercial projects?
Not on the sourced material. Matter is a device interoperability standard from CSA-IoT, positioned around smart-home and cross-ecosystem compatibility, with lighting and electrical among its supported device categories. DALI is a lighting-specific protocol built on IEC 62386 with its own certification programmes. The DALI Alliance describes DALI+ and its new wireless-to-DALI gateway certification as bridges between DALI systems and wireless protocols including Bluetooth NLC and Zigbee. The evidence supports coexistence and bridging. How large a role Matter plays in commercial specifications is a judgment to confirm with your project specifiers. See the control section above.
Can I trust a “low glare” or “full-spectrum” claim on a datasheet?
Treat both as starting points rather than settled facts. A single UGR value describes a luminaire only inside its standard room and can differ significantly in practice; it is an approximation for the planner, and UGR values are compared by classification band rather than by decimal. “Full-spectrum” has no standardised pass/fail definition. Ask for the photometric file, the SPD and colour-rendering metrics reported to a named method. The glare and colour sections explain what each document can and cannot establish.
What does D4i actually give me at replacement and service time?
D4i is a DALI-2 extension with mandatory data parts: Part 251 luminaire data, Part 252 energy data and Part 253 diagnostics data, plus Part 250 integrated bus power supply. The driver stores luminaire information such as colour temperature and optical distribution, and reports energy use and diagnostics. At replacement, the luminaire’s identity and history travel with the driver rather than living in a commissioning file. It also enables plug-and-play connection of sensors and network lighting controllers, particularly with Zhaga or ANSI C136.41 connectors. See the D4i subsection.
Are circadian specifications tender-ready yet?
The measurement framework is settled — CIE S 026:2018 defines melanopic EDI, and the Brown et al. (2022) targets are adopted in CIE TN 015:2023 and endorsed in CIE PS 001:2024. The design guidance is not: the CIBSE/SLL position statement describes itself as a position statement, not a design standard, and states the evidence is not yet sufficient to prescribe universal design formulae. Certification schemes such as WELL do specify thresholds. Whether your customers write melanopic requirements into tenders will vary by project type and region — a judgment, not a sourced fact. See the circadian subsection.
