Amid today’s golden age of digital technology, new developments in lighting control systems allow for smarter data input, conversion, and application than ever before. Until we achieve fully controllable wireless lighting, manufacturers are competing to integrate the capabilities of solid-state lighting with existing systems, protocols, and installation methods. Understanding the components of control systems, how they interact, and how to represent control concepts is key to project delivery.
Any lighting control system can be reduced to a few elements: input electricity; input data, such as an on–off signal from a switch or sensor; data-to-information converter, such as a computer chip that translates daylight sensor data into a dimming signal; information transmission through wires or wireless signals; and information output in the form of visible light from a source.
Prior to the development of digital control systems, physical wires had to be snaked from each fixture to a centralized control center. Transformers and dimmers, which required large coils of copper housed in metal boxes with heat-dissipating fins, needed to be located in designated fireproof spaces. To provide the desired control of electric light, these systems drew an immense amount of energy and physical resources. Though contemporary systems may still incorporate elements from these legacy systems, the days of their reliance are numbered as wireless and digitally addressable systems mature.
Data In, Information Out
The terms data and information are often used interchangeably, but they have distinct meanings when describing a control system: Data entering the system is processed, and the resulting information learned from the data is what controls luminaires. Although both electricity and data flow through any lighting system, this article will focus on how control systems make this data-to-information transformation possible.
Knowing when to turn on, turn off, or dim a source requires information that enters a control system as data at an input device. Any given light fixture is limited in control by the types of information it can accept. Whereas legacy sources only allowed switching or dimming, solid-state light sources allow up to four control variables, depending on the driver and LED specifications: switching, dimming, color temperature, and color.
Furthermore, nuances for each exist: Lights may dim to 10 percent, 5 percent, or 1 percent output before switching off; color may be created with RGB (red, green, blue), integrate amber for richer colors, or even include white LEDs for nicer white light distinct from color-changing capabilities. These options are available not only because the physically small nature of LEDs allows many diodes to fit within a fixture, but also because of the new capabilities of digital controls.
Today, digital systems may handle a diverse array of sensor data such as photocells and occupancy sensors, visible-light or infrared cameras, and geofencing technologies, all able to gather data from the environment. Building and energy codes, which once only acknowledged connected loads, now include requirements for automatic controls to limit electric lighting usage when not needed.
Brent Protzman, manager of energy information and analytics at Lutron, notes that ANSI/ASHRAE/IES Standard 90.1–2010, the 2012 International Energy Conservation Code, and California’s 2013 Title 24 energy standards all now require occupancy sensing as well as multilevel light control and daylight controls in certain spaces, such as open offices. Sensors may be standalone pieces of hardware or integrated into the light source itself.
The digital nature of LEDs allows easy integration of onboard sensors that can speak to the driver and control the light source, or provide feedback data to a larger control system. While onboard control sensors were originally developed in fluorescent fixtures, digital protocols have allowed a much finer degree of control and flexibility, and decreased physical size of components. For example, many LED streetlights now have a computer chip programmed with scheduling data that lowers lumen output when traffic dies down after evening rush hours to save energy and prolong fixture lifetime. The chip may also talk to adjacent fixtures, creating a mesh network that feeds data back to management controls. A distributed network where each fixture has its own controls is inherently more robust than a centralized system, particularly in outdoor environments, since each fixture is an independent, self-operating entity.
Sensors integrated into LED fixtures can also provide feedback about the life and health of the driver and source, or serve as node points for other environmental sensors such as motion, temperature, or illumination. Retail and other commercial spaces have begun integrating location-tracking technologies, such as that by GE Lighting and ByteLight, into light fixtures. Whereas the vacuum of the A-lamp once helped us see, these digital sources now see us.
Data Conversion and Transmission
At the heart of any control system are components, devices, and software that convert complex input data signals into language that light sources understand: switching and dimming. A photocell can only report light levels; it can’t decide when to dim the luminaires or when to warm the color temperature by dimming down blue diodes and turning up reds.
These conversion elements form the backend of a control system and comprise circuit boards, data compiler boxes, relay panels, and fixture drivers. In replacement LED lamps, data conversion may occur within accompanying mobile apps, base stations, or the lamp enclosure itself. In larger installations, centralized controls may operate over entire buildings or campuses, using any number of protocols and control hardware.
Cutting-edge building management systems from companies such as CommScope, Lutron, and Schneider Electric all include various data input options, control settings, and feedback data analysis capabilities. These systems promise a Rosetta Stone, translating data inputs from users, building sensors, light sources, HVAC, and other connected building systems into a smart learning machine that can tune the building by modifying daylighting controls or adapting schedule settings based on occupant-use patterns to minimize energy use.
Where legacy control systems require a home-run connection and command station, networked digital controls are distributed and may not require a center at all. Europe and much of the rest of the world have adopted DALI (Digital Addressable Lighting Interface) as a standardized networked protocol. The U.S. has seen far fewer DALI installations to date; instead, we rely on proprietary digital systems by manufacturers or open protocol systems.
Regardless of platform, these control systems allow fixtures to be powered from any available source, data wired in series (or controlled wirelessly), and then digitally addressed on the system after installation. Fixtures may then be zoned—or grouped with other fixtures for particular lighting presets—or configured into scenes, irrespective of installation location and wired connections, enabling spatial flexibility, local control provided to designated fixtures, and assignment of pre-set levels to each fixture. Master control through a computer interface can then be accessed via any wired or mobile device on the system.
Dynamic Lighting, Dynamic Controls
Arguably the most visible development in LED lighting is the ability to address nodes, which allows designers to create dynamic scenes in white light or color. Although some manufacturer literature uses “node” to reference the point at which data and power are combined and fed to multiple fixtures, this article uses the term to mean individual pixels in a system.
Digital multiplex (DMX), the industry standard for theatrical lighting control since the 1980s, was designed for use with a theatrical dimming board. Today, it is the most widely used data protocol, or digital lighting controls language, for dynamic architectural lighting. DMX has two units of measure: the channel and the universe. While a single channel is analogous to a single dimmable circuit in a conventional system, one universe of DMX supports 512 channels. In an RGB color-changing node, each channel represents one color of light, or three channels. A quick calculation reveals that 170 nodes of RGB (totaling 510 channels) can be controlled by one DMX universe, and large systems can contain multiple universes.
Manufacturers of architectural color-changing systems have evolved away from the theatrical board. Instead, they have developed control boxes of various sizes that receive scene data from a flash drive, computer, or Web interface and send out DMX signals to fixtures. Design and control software, often provided by the manufacturers, may be used to develop scenes from standard templates or map video input onto a grid of nodes. (But just say “no” to the default rainbow-fade setting.)
For all its ubiquity, DMX is still limited when handling large installations. Increasingly complex setups use direct Ethernet connections and computer management to populate pixels more akin to a monitor than theatrical lighting.
Connecting Devices and People
For the foreseeable future, electricity will continue to flow through copper wires from power sources to fixtures. However, control data can travel through many media: optical fiber, CAT 5 cable, or wireless signals. Lutron’s Protzman says his company’s wireless controls are increasingly used in commercial and retrofit applications because of the cost savings that come from the reduction in cable material and installation time.
As ambient computing and the Internet of Things find homes in our built environments, organizations such as ZigBee Alliance and EnOcean Alliance have developed alternate standards to ensure interoperability across hardware. ZigBee, according to chairman and CEO Tobin Richardson, lobbies manufacturers to develop all types of products with the Institute of Electrical and Electronics Engineers (IEEE) 802.15 standard for mesh-networking, which operates at lower power than the IEEE 802.11 standard, which Wi-Fi uses, and avoids potential conflicts with computers and mobile devices.
Meanwhile, EnOcean lobbies manufacturers, specifically in the building industry, to adopt a technology produced by its namesake German manufacturer, which transmits low-powered data signals by harvesting energy from micro-movements present in all physical objects. Regardless of protocol, electrical things in our buildings will soon talk to each other, suggesting opportunities we haven’t even imagined.
Building-scaled lighting control systems now offer many bells and whistles, and technologies across multiple manufacturers only add complexity. Communication among project stakeholders is critical to implementing robust systems that may take advantage of opportunities offered by LED technologies. However, because lighting control is no longer limited by physical wired connections, engineering wiring diagrams now do little to represent control concepts.
To that end, lighting controls diagrams developed by the lighting designer, architect, or interior designer serve to aggregate the spatial information in a wiring diagram with temporal information in a controls narrative and scene schedule. Such diagrams provide design, engineering, and construction teams, as well as the owner or facility manager, with an overview of a control system’s intent, including which fixtures should operate together, when and how scenes change, and the locations of automatic and dynamic controls.
Soon enough, all building lighting will be completely wireless, fully networked, sensored, and seamlessly controllable via Web or mobile apps. In the meantime, smart integration with existing systems is critical to transitioning building projects, which will continue to require multiple types of control for various design elements throughout the building. The options are plentiful, but, in the end, most lighting control scenarios still boil down to the basic questions. When should the lights be turned on? How bright? When should they be turned off? What is their purpose? Ultimately, what we seek are integrated systems that provide the light we need at the times we need it, monitor and minimize energy use, and entertain us when the moment is right.
Dan Weissman is director of Lam Labs at Lam Partners, in Cambridge, Mass.
A list of introductory articles that discuss controls and their relationship to solid-state lighting.
“Controlling LEDs,” by Lutron (Ethan Biery, Thomas Shearer, Roland Ledyard, Dan Perkins, Manny Feris), May 2014. Available at: bit.ly/1kFPBlt.
“Maximizing energy savings with control over light,” by Koninklijke Philips Electronics, April 2013. Available at: bit.ly/1oHUth6.
LED Lighting Explained, by Jonathan Weinert, published by Philips Solid-State Lighting Solutions, 2009. Available at: philips.to/1EyxFUL.