Setting the stage for a luminaire-level revolution
By Charles Knuffke
When thinking about lighting controls, it’s amazing to look at where we’ve been and where we’re headed—and how much control/sq ft we’re now achieving. While we’ll end up at the current state of technology (luminaire-level lighting controls), it would be helpful to first consider the founding energy-saving controls of the past, still found throughout existing buildings and at new construction projects. We’re talking about the triumvirate of basic electromagnetic lighting controls—contactors, relays and powerpacks.
Contactors were initially developed over 100 years ago due to the early need to isolate large electrical sources from the hardware it powered, but in our industry we’re more familiar with them in the form of the multipole lighting contactors used to control a bank of lighting circuits On and Off. Whether mechanically held or electrically held, these were the first lighting control devices used other than standard wall switches and they’re still often called out to control parking lot lighting circuits, particularly when multiphase power is called for.
ORIGINALLY USED FOR RESIDENTIAL applications, low-voltage remote control relays came to the market around the early 1950s. Sold as a handful of separate components—relays, a transformer and a panel—contractors would purchase and install them in their high-end residential projects.
While lighting relays started on the residential side of the fence, they soon showed up in commercial construction projects, especially when manufacturers started selling preassembled panels with simple internal controls that would allow groups of relays to be turned On and Off by timeclocks. The benefit over contactors was that while an entire switch bank of relays could be turned Off at one time, anyone staying late could override just the lighting in their individual area. These “Off sweeps” would be scheduled repeatedly until all the building’s lights were Off.
The introduction of occupancy sensors brought about a different circuit control device—the powerpack. Relay panels were well suited for controlling lighting from within the electrical closet, but when plans called for a single circuit to be broken up into multiple switch-legs, it was costly to run a load wire in parallel to multiple relays and then home run each switch-leg to the areas they served—all those conductors and the larger conduits they required were expensive in both materials and contractor labor. For occupancy sensors, manufacturers realized the solution was combining a small relay and transformer in a knockout-mountable device allowing branch circuits off the main conductor to be easily controlled. Since contractors were only running a single circuit out from the electrical closet, this approach represented a considerable savings in labor, pipe and wire.
SO WHY THIS HOMAGE to these On/Off control devices of the past? Because they illustrate the straightforward path that we’ve taken starting with large-area control devices and moving ever forward with smaller, more granular controls.
- Contactors: Enabled control of multiple circuits
- Relays: Enabled control of individual circuits
- Powerpacks: Enabled control of circuit switch-legs
There have been other lighting control devices along the way—dimmers for aesthetics and controllable circuit breakers within panelboards—but in the early 2000s, we saw the next significant leap forward for commercial energy saving lighting controls: digital protocols like DALI appeared where the control of the connected lighting wasn’t by an external device but by the ballast itself—the logical next progression after controlling switch-legs.
Having worked on several DALI projects when it first appeared in the U.S., it seemed this new protocol/technology would become the standard when designing lighting systems for new projects, especially thanks to its digital communication and default logarithmic dimming curve. However, there were clearly problems with DALI on those early projects—it turned out that installing and documenting luminaires with multiple line-voltage circuits, but a single separate low-voltage DALI conductor, was new territory for installers. Additionally, assigning and then determining addresses to each of the ballasts so they could be individually programmed and controlled was a decidedly hit or miss function depending on the software, the start-up team…and seemingly the phase of the moon. Lastly, few input devices could communicate via the DALI protocol, so additional interface devices were needed, which meant more cost and complexity. So, while there were great expectations for DALI, it didn’t catch on as originally hoped.
The issue with individual addressability of luminaires wasn’t in the concept but the execution. It would take time for technology to catch up with the ideal solution—eliminate the wire between the luminaires by moving to a wireless communication network, assign a unique address to the luminaire controller at the time of its manufacture, and, for good measure, simplify the controls by integrating both an occupancy and daylight sensor in the controller. Finally, put it all in a small package that can be easily mounted into general lighting luminaires via a standard-sized
knockout. This is where the industry is now: luminaire-level lighting control, or LLLC.
THE MOVE TO LLLC DEVICES will revolutionize our industry, representing a major inflection point in how spaces are designed and controlled. And we’re seeing market actors pushing projects to move in this direction. The IECC 2018 model energy code required occupancy sensor control in large open offices, but limited to zones of no more than 600 sq ft. True, these offices can be designed with simple analog sensors, but when intelligent LLLCs are used, the code provides an extremely beneficial accommodation for the space’s occupants; instead of unoccupied zones going completely Off when other zones are still occupied, the lighting instead can remain on at a 20% or lower level. Going to a low level instead of full Off is much more comfortable for people in the space, as evolution has blessed us with eyes that are particularly adept at picking up lights going completely Off in our peripheral vision which unfortunately will disturb our concentration.
And while we’re mentioning energy codes, in a draft version of the 2022 Title 24 code available on the California Energy Commission’s website, the IECC’s open office control intent is included in the upcoming code. (This language is subject to change, but unlikely to change significantly as it’s the most substantial lighting advancement in the code.)
Another proponent of LLLC is the DesignLights Consortium, which requires manufacturers of networked lighting control systems (NLCs) to report if their systems include LLLC devices since the earliest version of their Qualified Product List for NLCs.
Looking back at the earliest lighting controls, it’s truly a breathtaking list of advancements—each one providing not only more granular control of lighting but making increasing use of interacting layers of controls. And setting the stage for even more advancements by making LLLC-enabled luminaires the carriers for enticing next-level technologies in the built environment.