Specifying LED Color-Tunable Products

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Specifying LED Color-Tunable Products

Specifying LED color-tunable luminaires is dependent on being able to make accurate comparisons between products. Yet reporting performance values for color-tunable products is much more complicated compared to other LED product categories. The range of possibilities makes it more challenging to measure and communicate performance, and there are no standardized test procedures for these products.

DOE’s evaluation of color-tunable luminaires highlights a number of confusing issues, related to manufacturer cut sheets and product ordering, that make specifying these products particularly challenging.

Cut sheet information the specifier needs

Specifying color-tunable luminaires and controls can be difficult because relevant information is often missing from the product cut sheet. The following list outlines the kind of information (features and data) that specifiers need to know, providing a handy checklist for specifiers, and helpful guidance for manufacturers.

  • Kind of color change: White-tunable, dim-to-warm, full-color-tunable (RGB etc.), or some combination of the three. (See definitions in Understanding Color Tunable LED Products)
  • Color module: Does the product use, for example, a Lumenetix “Araya” module, or an LED Engin “LuxiTune” module? Since multiple manufacturers may use the same module, this may be a way for a designer or engineer to specify multiple manufacturer names for a luminaire type, but get exactly the same color capabilities with the same or similar controls. If it uses a proprietary array or module, call it “proprietary.”
  • Control protocol option(s): Does the product use a proprietary control system, or wired controls (e.g., 0-10V, DMX512, DALI), or wireless control protocols (e.g., Zigbee, Wi-Fi, Bluetooth)?
  • Driver options: Which driver option comes standard, and if there are other options, how is the catalog number modified to reflect the different driver? Does the expected input from the dimmer to the driver follow a linear, square law, or power law curve; and does the driver respond to that input by delivering light output in a linear, square law, or power law curve? These questions pertain to 0-10V, DALI, and DMX protocols, as well as to wireless controls protocols.
  • How to specify a complete functional system: Information needed includes compatible user interface, complete system wiring diagram (not just a one-line diagram), any needed black-box control devices, housings, cables, connectors, etc. If a black box device is needed between control and driver, what is the maximum and minimum number of LED drivers/luminaires that each device can control?
  • Cable type, connectors, and related requirements: Between user interface and black-box device and between black-box device and luminaire, is the wiring for standard or low-voltage power, how many wires of what wire gauge are needed, what is the maximum run length, and what are the requirements for the cable runs (in conduit? Daisy-chained? Star-pattern?)?
  • How to order the product: Is ordering through an electrical distributor, directly from the manufacturer, through a local representative, through an online store, etc.?
  • Power use: What are minimum watts at undimmed output, maximum watts at undimmed output? Are they different at different color settings?
  • Dimming performance for most common driver/control combinations: What is the minimum dimming level? Does the product dim to off, or drop to a specific output level and then off?
Guidelines for performance testing reporting

Guidelines for performance testing and reporting have not yet been established by the industry for color tunable luminaires. In the interim, manufacturers may consider providing the following data for the minimum, mid-range, and maximum CCT settings:

  • Luminaires with more than three LED primaries (e.g., full-color-tunable luminaires or white-tunable luminaires with non-linear color capabilities) may need to provide testing at five to seven points along their “white” range in order to provide specifiers with higher precision spectral and light output performance data for circadian health applications. See Testing LED Color-Tunable Products for more information.
  • Candela distribution data file in .ies format, plus graphical candela curve for at-a-glance light distribution information. Alternately, provide a single candela distribution file, with multipliers for different combinations of intensity and color setting.
  • For white-tunable and dim-to-warm products, provide graphical SPD plots and electronic color files (.spdx) for at least the minimum, maximum, and mid-range CCT settings. Provide complete spectral power data file in no more than 5 nm increments between 380 and 760 nm. (This is standard LM-79 sphere testing data, except that it is provided for multiple color settings.) Color metrics such as CCT, Duv, CRI (Ra), Rf, Rg, and R9 can be derived from these data.
  • For circadian health applications, it may be helpful to provide summary data of melanopic1, 2, and photopic lumens and efficacy.
  • Percent Flicker and flicker frequency at maximum, minimum, and mid-range output3.

A sample table for some of this technical information is shown below.

1Irradiance Toolbox user guide. Download at: http://lucasgroup.lab.ls.manchester.ac.uk/research/measuringmelanopicilluminance/

2Irradiance Toolbox spreadsheet: Download at: http://lucasgroup.lab.ls.manchester.ac.uk/research/measuringmelanopicilluminance/

3IEEE Standard 1789-2015: IEEE Recommended Practices for Modulating Current in High-Brightness LEDs for Mitigating Health Risks to Viewers.

Sample performance table

Sample table of product performance data for color-tunable luminaires.

(Note: SPD icons and all numerical values were generated for illustration only. They do not represent actual products.)

Issues encountered in ordering LED color-tunable products

In order for specifiers and facility managers and researchers to use color-tunable products, they must be able to examine product literature for options and features, and build a catalog number so that the correct product can be priced and ordered. What follows is a list of issues recently encountered by lighting-knowledgeable staff in ordering these systems.

Product Identification
  • Difficulty in identifying whether a color-changing luminaire is full-color-tunable, dim-to-warm, white-tunable, or some combination of the three. Clear vocabulary and descriptions are needed. If full-color-tunable, what LED primaries are used in the color module?
  • Difficulty in determining whether a luminaire is available in the U.S., and includes National Recognized Testing Laboratory (NRTL) listings. International manufacturers often do not indicate in which markets their products can be sold, and may not indicate whether products meet national and regional code requirements.
Product Specification
  • Insufficient information. Product tech sheets frequently omit important information for the specifier, and product ordering codes do not reflect important options (such as LED driver or dimming protocol choices).
  • Confusion between a manufacturer and the vendor. Many cut sheets from different vendors showed virtually identical products. It became clear that multiple companies were marketing products that were made by another unnamed manufacturer. Any differences in driver type, control type, luminaire features, warranties, etc., should be clearly stated on the cut sheet to minimize confusion. The vendor needs to specify which company accepts the liability of product safety, and who provides service and replacement parts if there are any installation issues or future replacement issues.
  • Confusion between a color module manufacturer and the luminaire manufacturer. It is helpful to the specifier to have the brand and module number called out on the luminaire cut sheet. In cases where the specifier has to provide a three-name specification, a single module used in three luminaire manufacturers’ products can provide some guarantee of compatibility with dimming systems, no matter which of the three is ultimately selected for the project.
  • Unclear and inconsistent information. The specification sheets for some products made the design of a color-changing lighting system inordinately complicated. The component terminology was obscure, and it was challenging to specify a complete system. Furthermore, the order number for each component was 12 or more digits, with no guide to the significance of each digit. Sometimes a knowledgeable manufacturer’s representative can help with the system design, and record drawings are sent to the specifier to verify the system ordered. Unfortunately, the numbers on the record drawings may not match the specification, so additional footwork may be needed to verify that the product ordered (e.g., DL LMT019-4DL-RS-60D-120-VOL with LX-LMT-LCT) is the same product listed on the record drawings (e.g., DL-LMT019-60K-L13-RS-4DL-60D with HSG: DL-LM).
Distribution Channel Identification and Obtaining Product/Shipping/Cost Information
  • In some cases it is difficult to find contact information for representatives or distributors for the products on vendor websites. This means there is no one to respond to local field problems or to local code requirements. If a vendor is handling orders and field issues, then that vendor must obtain the needed experience for working in the architectural construction market.
  • Pricing is often difficult to obtain, no matter how the product is sold and procured. It is a tremendous help when manufacturers and vendors provide clear instructions on how to get accurate pricing estimates for different product options, including estimated markups and shipping costs.
  • If a color-tuning product is not offered through conventional electrical distribution channels, but is instead only offered through a distribution channel for specialty medical applications, for example, it is important for the manufacturer to make that clear on its cut sheet because it may need to be procured through another supply channel.

Avoiding the problems listed above will result in more satisfied specifiers, clients, and users. It is incumbent on the manufacturer to provide product literature and specification support that makes the process easier.