Originally published in tED Magazine, the official publication of the NAED. Reprinted with permission.
Luminaire-level lighting control (LLLC) combines the energy code-mandated functions of occupancy and light sensing in an LED luminaire capable of operating autonomously using an onboard lighting controller. The latest generation of products adds a layer that enables programming and collection of useful occupancy and other data.
Typically installed in office buildings and schools, LLLC is also suitable for high-bay, parking garage, gas station, and other applications, particularly luminaires that are high wattage and have long operating hours and would therefore benefit most from enhanced energy savings. The Department of Energy estimated the installed base of networked luminaires will grow from less than one percent currently to nearly a third of all lighting by 2035.
“LLLCs combine LEDs, controls, connectivity, and data for a flexible lighting product that can improve occupant comfort and space utilization,” said Martin Mercier, Strategic Marketing Manager, Connected Systems, Cooper Lighting Solutions. “In the market, there is definitely a growing interest as these systems are getting easier to install, commission, and use.”
A basic LLLC solution starts with a luminaire fitted with LEDs connected to driver(s). A lighting controller is added as an integral component of the driver(s) or as a separate device that uses a relay to send dimming signals to them. The controller also features a microprocessor for programmed (or preprogrammed for “out of the box” energy code-compliant) operation, enabling the luminaire to operate autonomously. Finally, we have the input sensor(s), which may include an occupancy or vacancy sensor, light sensor (for daylight response), or a hybrid unit combining these functionalities. All control components are pre-installed in the luminaire.
As a subset of networked lighting control, a number of solutions incorporate radios for wireless communication between the luminaire and gateways or hubs and/or a central server that constitute the lighting network. If connected to a server, along with energy data, highly granular occupancy data can be collected for purposes such as optimizing space utilization. With Bluetooth or Wi-Fi connectivity, additional capabilities, such as asset tracking and contract tracing, can be implemented. Theoretically, other sensor types, such as air temperature sensors, can be incorporated, along with additional control strategies such as shade, plug load, and HVAC control.
A 2021 Northwest Energy Efficiency Alliance (NEEA) study categorized LLLC as one of three types of systems: Clever, Smart, and hybrid of the two.
Clever: These systems enact high-end trim, dimming, occupancy sensing, and light sensing. The luminaires install in a plug-and-play manner and require little or no additional programming.
Smart: These systems include capabilities of Clever systems but feature the ability to communicate and analyze energy and non-energy data for various uses such as space utilization, asset tracking, and more.
Clever-hybrid: These systems include a standalone gateway and provide additional capabilities such as monitoring but do not provide the full data collection and analysis capabilities of a Smart system.
Advantages and disadvantages
LLLC offers several advantages. Overall, by making each luminaire a control point, control is highly flexible, responsive, and therefore generally more energy-saving. According to the NEEA, average lighting energy savings with LLLC exceed 60 percent.
For the electrical contractor, LLLC can simplify wiring and reduce time installing discrete lighting control devices. For the electrical distributor, it offers an energy-saving, value-added solution that can streamline product schedules for lighting projects. The designer gains flexibility; the owner gains high energy savings, potentially data, and the ability to fine-tune and reconfigure the system with relative ease in the future; and users interact with a lighting system that respects comfort and offers personalization potential.
“Wireless systems and LLLC will continue to simplify lighting control design and specification because you don’t need to have all the project details upfront,” said Craig Casey, Building Science Leader, Lutron Electronics (Lutron.com). “Contractors don’t have to be worried about wired zones or zone configuration, just power to the fixture. Because of the tremendous opportunity for enhanced lighting performance, the lighting designer has a broader palette than ever and can enjoy greater freedom to design lighting that meets the individual needs of every job.”
“For electrical distributors, LLLCs provide an integrated option between the luminaire and controls, thus reducing the overall SKUs a distributor may need to onboard and simplifying the management of the flow of goods,” said Rahul Shira, Senior Product Marketing Manager, Signify (Signify.com). “In simple terms, by integrating the occupancy and daylight sensor into the luminaire, the SKU counts drop from three to one, significant savings.”
“Because these devices are typically installed by the fixture manufacturer, driver compatibility is resolved before the fixture is shipped,” Casey added. “Distributors don’t have to worry about compatibility and can be confident they are selling the contractor a system that will result in an easy installation and setup with limited callbacks.”
The primary inhibitors are the luminaire’s higher base cost, potential higher complexity of the project if a Smart system is deployed, insufficient value or savings for a given project, and uncertain owner interest in non-energy benefits generated by collecting data. According to the 2021 NEEA study, compared to a luminaire with no controls, the cost of LLLC in 2020 was estimated at an average $0.58/sq.ft. for Clever, $1.16/sq.ft. for Smart, and $0.78/sq.ft. for hybrid systems based on a prototypical 40,000-sq.ft. office building. NEEA noted, however, a significant decrease in costs from 2019 to 2020, suggesting these systems were becoming more competitive with a falling initial cost that can be further softened by rebates when applied in a retrofit.
“In retrofit projects, LLLCs unlock the path to claim higher rebates,” said Shira. “In most geographies, these rebates range from $15 to $65 per sensor integrated into an LED luminaire and are in addition to the rebates offered for installing LED lights. When coupled with the installation savings and deep energy savings offered by LLLCs, a return on investment of less than two years or even one year becomes very achievable.”
“LLLC will grow in market penetration and evolve into more advanced solutions with more benefits beyond lighting, making it easier to break building system silos with open protocol,” Mercier said, advising distributors to get ahead of the curve by becoming familiar with the technology and products through education. “This already exists, but market penetration and functionalities will grow by large factors. It also leads to standardization, so more devices can interact as part of an IoT ecosystem—think temperature sensors for room HVAC control, Microsoft Office suite tools for hot desk booking, Parking Guidance System integration, wayfinding for warehouse lifts, and so on.”