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Horticultural Lighting FAQs
As the DLC operates the Horticultural Lighting Program, we will continually update this list of Frequently Asked Questions for the benefit of all QPL and program users. The FAQs below represent answers to common questions about submitting a product to the DLC Horticultural Lighting QPL and how our requirements and policies are interpreted. They are explanatory only and should be viewed as such. In all cases, please refer to the Terms of Use for the operative rules regarding participating in the DLC QPL.
General
No. The DLC is interested in the performance of the production-ready product seeking qualification. As such, test data on prototypes will not be accepted for DLC submissions. Testing must be on production-ready models that are identical in design and construction to those that are being or will be sold.
The DLC does not have a complete set of required terms and conditions and will allow manufacturers significant flexibility relating to common mechanisms of a warranty. The DLC does expect the entire set of warranted products to be covered when used as directed by the manufacturer for a minimum of five years.
The first step towards getting your horticultural lighting product listed on the qualified products list is to create a manufacturer account on the DLC’s web portal.
Start a new application and select “Horticultural” as the application type. Informational prompts and explanations are built into the application to guide you through the process. However, if you have questions or need clarification email horticulture@designlights.org.
When all information is complete, submit the application along with any supporting documentation.
A reviewer will complete a thorough review of your application in the web portal, identifying any issues which require clarification. The web portal stores a complete record of all correspondence tied to each part of the application to make it clear and simple to understand where follow up is required.
When all issues have been resolved, and all materials have been accepted, an invoice will be generated through the web portal. Once paid, your product will be posted on the horticultural lighting QPL within 24hrs. You may now market the product as DLC® qualified. Please refer to the DLC’s Logo Guidelines for instructions on proper marketing of a DLC qualified product.
All products’ specification sheets must show the maximum rated ambient temperature, in Celsius. This information will be used by the reviewer to evaluate component lifetimes.
The definition of the lumen curve (“V-lambda”) stops at 780nm. Consequently, many products which underwent legacy testing techniques based on human visual metrics do not necessarily contain spectral information for the portion of Far Red between 780-800nm. Since the DLC is collecting information on Far Red flux for informational purposes only, reviewers will allow test reports missing data in this range prior to October 15, 2019.
After October 15th, 2019, if a newly applying product has insufficient data covering the complete Far Red range for flux output or flux maintenance, both fields will be marked as zeros on the horticultural lighting QPL. If the DLC decides to count Far Red flux as eligible for efficacy threshold calculation, this policy will likely become more stringent, and we urge all stakeholders to collect the widest range of wavelengths possible when testing fixtures and components.
Any removable accessories not required to achieve full light output, such as cameras and sensors, should be removed during whole-fixture flux and efficacy testing. Any non-removable accessories with controllable power states that are not required to achieve full light output, such as microphones or external luminaire power connections, should be disabled or powered down during testing.
In the early stages of the horticultural SSL marketplace conversion, the DLC horticultural lighting program is meant to control performance risk. Therefore, the program is not allowing scaling or family grouping. Every fixture will be individually evaluated, since the traditional means of defining a “family” or “group” for general lighting are not applicable across the variables of spectrum, power, size, and flux output.
However, the DLC will allow certain flexibility for product designs that present measurement challenges. For example, if a fixture with a central power supply and two “light bars” extending outward were longer than any available integrating sphere could accommodate, the DLC reviewer will allow the testing to proceed with the two “light bars” mounted parallel to each other, nearly halving the length of the fixture and allowing it to fit within the test equipment. In contrast the DLC reviewer will not allow this same test setup to test only one bar attached to the driver, with the 2-bar performance then determined by multiplying the performance of the test model in an effort to estimate the performance of the “double long” fixture. The total power and flux must be measured at all times.
Similar testing challenges as mentioned above should be discussed prior to application submissions by emailing horticulture@designlights.org. The DLC reserves all rights to make final judgments.
The IES file (formally known as a LM-63 document) is a useful format for reporting and modeling light distribution. The file format and its common usage in design software assumes measurements based on human-vision terms of candelas and lumens. While it is possible to place appropriate horticulturally based PPF measurements into the format of an IES file, significant care must be taken to appropriately warn the end user and design software of this modification. To encourage the adoption of easy-to-use formats for the adaptation process (like the new ANSI/IES TM-33) and updated software that will use automate the application of appropriate context in designs, the DLC is using PPID plots as a placeholder while the measurement, testing, and modeling ecosystem adapts to these new standards.
PPFD plots with a “heat map” generated with varying PPF density across an application plane, are useful tools for end users. The DLC is participating in standards development work to define uniform and repeatable ways of measuring and reporting these values, and will consider requiring them to accompany or replace PPID images or TM-33 documents as technical maturity of the sector advances.
Lighting products often use an AA-BB-CC-XXX structure for model numbers or Stock Keeping Units (SKUs) that refer to various options and permutations. The horticultural lighting QPL requires individual testing of any permutation that produces different outcomes. For example, two different spectral distributions on the same fixture chassis would require two separate applications and listings, and would not be listed by a [XX] or [AA,BB] on the product’s QPL listing.
An [XX] entry implies the DLC approval of all variables represented by this placeholder. Allowable entries include options that do not affect the product’s operation or are completely covered by testing (see driver performance details). Examples of this include drivers, cord length, housing color, and similar variables.
If there are specific variables that meet the DLC’s requirements, while others that do not, only those approved variables should appear on the SKU entry for the DLC QPL. The reviewer will check specification sheets and marketing brochures to ensure that only approved variables are clearly noted as DLC qualified, and that non-approved variables are clearly noted as not being DLC qualified.
The only exception to this requirement is a specific voltage designator type. If a model number has a voltage designator that encompasses a voltage range where the product does not meet all of the technical requirements across the range, the submitter can qualify the product at the voltages where the product meets the technical requirements. For example if the voltage designator is “MVOLT” which notes that the product can operate between 120 volts and 277 volts however the product only meets the technical requirements at 277 volts, the model number can still be qualified using “MVOLT” and the voltage listed on the QPL will be limited to 277 volts.
Yes, if a product has any functionality that enables it to adjust or vary the PPID of the emitted flux (i.e. field adjustable light distribution (FALD)), the intention is for it to be eligible when tested and listed at a specific distribution.
Products employing adjustable spatial distribution will be required to include “*field adjustable spatial distribution” at the end of the products model number and a description of the tested PPID orientation must be included in the downloadable PPID image provided on the QPL. For example, if a FALD product with rotatable light bars was tested with all bars aimed at nadir, the provided PPID image shall provide a note describing the corresponding distribution setting. E.g. “PPID corresponds to all bars pointing at nadir”.
Supplemental Documentation for Field-Adjustable Light Output Products and Field-Adjustable Light Distribution Products that describe the functionality of the product features may be requested along with the application.
Yes, as long as the highest wattage setting was tested in the submitted LM-79, ISTMT and benchtop electricals (if applicable), these products are eligible for qualification. These are defined as products that are capable of being adjusted to increase and/or decrease wattage by the end user. Products with adjustable wattage settings are required to include (field adjustable max output) at the end of their model number in the Web Application.
Supplemental Documentation for Field-Adjustable Light Output Products and Field-Adjustable Light Distribution Products that describe the functionality of the product features may be requested along with the application.
Per V3.0, the DLC requires all parent and single products to provide a TM-33 document (.xml file type), providing spectral and spatial distribution data for the fixture under review. TM-33 documents are separated into six elements: Version, Header, Luminaire, Equipment, Emitter, and Custom Data. In addition to all ‘required’ elements per TM-33-18, the following clarifications describe elements required for V3.0 compliance.
Header Element Required Fields
-
- Manufacturer
- Catalog Number
- Laboratory
- Report Number
- Report Date
Luminaire Element Required Fields
-
- Dimensions
- Number of Emitters
Emitter Element Required Fields
-
- Quantity
- Description
- Catalog Number
- Input Wattage
- Power Factor
- Data Generation – Intensity Scaling element field shall be ‘false’. Scaling with respect to laboratory measurements will be not accepted. Angle interpolation element must be ‘true’ or ‘false’, not blank.
- Photon Data – Photon Intensity data fields shall include ONLY PPF (400-700 nm). Photon Flux data field shall report ONLY PPF (400-700 nm).
- Spectral Data – Spectral Intensity shall be reported. Additionally, Emitter Name is required for spectrally tunable products.
CustomData Element Required Fields
-
- A custom data element called ‘Radiant Power to PPF Scalar Multiplier’ shall be reported for the ratio of PPF to Radiant Watts within the PAR range (400–700 nm). The ‘Any Data’ field shall describe this scalar multiplier. Unique Identifier data field must contain a Universally Unique Identifier (UUID), as defined by RFC 4122.
View a sample TM-33 file here.
Additionally, it is acceptable to report element fields described in TM-33-18 that are not detailed above. All data shall be reported to the number of decimal places per the V3.0 Horticultural Lighting Technical Requirements.
TM-33 .xml documents required for Hort V3.0 submission must contain photosynthetic photon intensity distribution (PPID) data produced by goniophotometric testing (per ANSI/IES LM-79-19) and spectral quantum distribution data (SQD) data measured in an integrating sphere (per ANSI/IES LM-79-19). In most cases, both sets of measurement data must be included in a single TM-33 .xml document. However, in some cases (see the below FAQ), the data may be separated into two TM-33 .xml documents, referred to by the DLC as “TM-33 .xml documents with SQD or PPID data only”.
TM-33 .xml documents that only contain SQD data must contain the SpectralData and EmitterSpectral elements but should not include the AngleInterpolation, PhotonData and PhotonIntensity elements (example). All other required elements must be present.
TM-33 .xml documents that only contain PPID must contain the PhotonData and PhotonIntensity elements but should not include CustomData and its nested elements, the SpectralData and EmitterSpectral elements (example). All other required elements must be present.
When a TM-33 .xml document with only SQD or PPID data is uploaded to the TM-33 Horticultural Lighting Presubmission Tool, an image containing the corresponding data will be produced, and a warning will state that the other required data set must be submitted in a separate TM-33 .xml document.
When testing a single model for SQD data and PPID data, submitted TM-33 .xml documents should contain both photosynthetic photon intensity distribution (PPID) data and spectral quantum distribution (SQD) data for ease of submission and review. However, the DLC will accept TM-33 documents with only SQD or PPID data when necessary. For example, separate TM-33 .xml documents will be accepted when testing is conducted in separate labs, and/or for level 2 applications where separate model numbers are tested.
For level 2 applications, SQD data, measured in an integrating sphere (per ANSI/IES LM-79-19), is required for the models with the minimum photosynthetic photon flux and efficacy. PPID data (per ANSI/IES LM-79-19), produced by goniophotometric testing, is required for each unique optical and distribution pattern. If the model numbers used for producing SQD data and PPID data within a family are different, the data may be submitted in separate TM-33 .xml documents.
An update application is required for listed products in the following scenarios:
- Updated products have new model numbers
- Updated products are no longer covered by the submitted safety certification documentation
- Updated products have worse performance for any of the metrics included in the DLC technical requirements
- Updated products have a better performance and the manufacturer would like the QPL to reflect the updated performance
- Updated products were submitted as a private label product or the updated products have been private labeled
The DLC relies on manufacturers to conduct due diligence to determine whether an update is required based on the criteria listed above. The DLC reserves the right to require update applications when necessary for application processing.
LEDs
For phosphor-converted “white” LEDs, the DLC reviewer will reference the ENERGY STAR program rules for applicability of LM-80 data. In sections 4.2 and 6.b.i.2 of this document, the ENERGY STAR rules only allow cross-applicability of LM-80 data to LEDs that perform within the chromaticity quadrangles defined in ANSI C78.377-2015.
In “single-emitter” or “narrow-band” LEDs, such as 440-nm “blue” or 660-nm “red” packages, a die produces a relatively narrow band of wavelengths. Their photons are not going through a phosphor conversion step and their chromaticity (if plotted) would be outside the ANSI quadrangles allowed to “share” LM-80 data. LM-80 data will be expected for each package in question. The DLC will follow ENERGY STAR program guidance on assessing assertions of series and successor identity for LEDs which share an emission profile, but have varying series, model, name and part numbers.
As the horticultural lighting program evolves the DLC reserves the right to modify this guidance as greater understanding and technical justification of applicability is provided. Attempts to claim cross-applicability of data via the ENERGY STAR guidance will be thoroughly scrutinized.
If LEDs are relatable per ENERGY STAR guidance, then only one question set entry in the application form is needed since the single “worst case” temperature of the LED package will be evaluated. For record keeping and auditing, applicants will need to provide the model number or ordering code for each relatable LED using this approach.
The DLC reviewer will be identifying the highest ISTMT of all observed LEDs that are classified as relatable and using this value for TM-21 projections. This may be any of the relatable models. The reviewer reserves the right to ask for proof and reasoning if only some of the LED types have undergone ISTMT and not others.
The measured and reported LED temperature in an ISTMT must be for the hottest LED of that model or type in the fixture. Guidance on how to determine the hottest LED is provided by the IES in Annex A of LM-84. The DLC reviewer will use the worst-case thermal condition, and will generally look for the LED chosen for ISTMT instrumentation to be in the middle of an array surrounded by the most neighboring LEDs. If the instrumented LED is not in this area, the DLC reviewer may ask for additional explanation, understanding that driver placement, structural elements, and other variables may change thermal flow for a product.
If a fixture uses LED device-based projections to meet the PPF maintenance requirement [Q90 must be at least 36,000 hours], the DLC will currently allow LM-80 data to be extrapolated with the TM-21 calculation method for the following units:
Lumens or radiometric watts will be accepted in new applications until October 15th, 2019.All fixtures using LEDs with LM-80 reports denominated in lumens or radiometric watts will be contacted by the DLC by December 31st, 2019 to request updated LM-80 reports in PPF units for these LEDs. There will be no extra fee associated with this request and verification. If the LEDs’ LM-80 reports are updated, their fixtures will maintain their listing through December 15th, 2021, which is the DLC hort program’s first two year cycle, including grace period. If the LEDs’ LM-80 reports are not updated, their fixtures will be removed from the DLC horticultural lighting QPL on June 16th, 2020.
Lumens or radiometric watts, converted to PPF with a one-time measurement of spectral content at the start of the device’s operating life will be accepted in new applications until October 15th, 2019. Fixtures using these LEDs will maintain their listing through December 15th, 2021, which is the DLC horticultural lighting program’s first two year cycle, including grace period.
Starting on October 15th, 2019, the DLC will only accept LM-80 reports denominated in PPF units for its Q90 threshold. The DLC may decide at its discretion to accept LM-80 reports that are clearly within the PPF range of 400-700nm based on the LED’s spectral signature, but are described in general terms of photon flux.For LEDs with emissions in both the PPF and Far Red bands (700-800nm), the DLC will require LM-80 reports to evaluate Q90 of PPF to be explicitly labeled appropriately with a separate reporting table for Far Red flux maintenance. In these cases, the descriptive term “photon flux” will be insufficiently specific and will be returned by the reviewer.
UV and IR LEDs are allowable in the DLC horticultural program.
All DLC testing must be conducted with all LEDs energized.
If the UV or IR LED has at least 25% of its per-device flux in the PPF range, during ISTMT testing the UV or IR LED must meet the flux maintenance requirement of Q90 ≥ 36,000 hours as shown by a TM-21 calculation based on an LM-80 in horticultural units.
If the fixture’s total PFFR output that is equal to or greater than 5% of the fixture’s flux from 400-800nm and the UV or IR LED type present in the fixture has at least 25% of its per device flux in the PFFR range (700-800nm), a TM-21 representing the photon flux maintenance in the far red region, PFMFR, must be provided for the UV or IR LED present in the fixture. There is no threshold performance requirement for PFMFR.
If no LM-80 is available, whole fixture LM-84 testing must be conducted.
The DLC does not require device-level SQD data from applicants and will typically accept the applicant’s descriptions of a device’s relative PPF or PFFR while reserving the right to request explanation.
Driver and Power Supplies
The horticultural lighting QPL allows multiple driver options for a single listed product to accommodate differing voltages and also to allow fixture manufacturers to manage supply chain complexity with multiple driver original equipment manufacturers (OEMs). When operating at its full power, each driver has slightly different electrical efficiencies at different ends of its input voltage range. The most accurate way to ensure that the lowest-efficacy operating state of the fixture is known would be to require full-fixture testing for each driver, at all input voltage extremes. However, this would be prohibitively expensive in both time and money.
As a compromise, the driver testing requirements call for fixture manufacturers to perform “benchtop” electrical testing of all drivers when operating at the fixture’s maximum designed power state and report the accumulated performance data. With the announcement on May 18th, 2020, only input driver input measurements are required and driver output measurements are no longer required. See this file for a suggested format reflecting the requirements released in this announcement.
The driver and input voltage combination that results in the highest wattage or lowest driver electrical efficiency (output power divided by input power) out of the global set in the benchtop report will be the test condition that should be examined in full-fixture LM-79 performance testing but the DLC may ask the manufacturer to provide detailed evidence to demonstrate the worst case driver thermals.
Other variables from the benchtop testing, like total harmonic distortion (current) and power factor, are also collected. Reviewers will search for the single highest and lowest value, respectively, in the data set, and ensure that these are listed for the fixture on the horticultural lighting QPL. Reviewers will examine both the benchtop report, and any LM-79 reports, to ensure that the most accurate data is provided.
Evaluation of a driver’s lifetime also follows a similar approach. The key difference is that the DLC cannot assume that different drivers have similar designs, components, and temperature tolerances. Therefore, each unique driver available for the fixture must feature ISTMT data and an OEM-provided time-at-temperature lifetime projection.
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