Daylight harvesting is another popular application for luminaire-integrated sensors and controls, making control of individual luminaires possible (although multiple lights can be connected to create larger zones that respond to a single input). So if you have a series of suspended fluorescent luminaires mounted in rows perpendicular to a window, the fixture in each row closest to the window can be specified with onboard photocontrol for daylight harvesting. Alternately, if the rows are mounted parallel to the window, a single luminaire with an integral light sensor may serve to control the entire row as a single zone. Solutions are thus possible for virtually any luminaire configuration in the daylit area.
Some manufacturers offer their luminaires packaged with a broader control system to offer solutions for certain applications. And some of those now offer integrated classroom lighting systems that provide flexibility and energy savings. Prudential’s Sense family of fixtures, for one, includes dimmable ballasts; teacher manual controls that provide switching from general to A/V modes, with dimming available in the A/V mode; luminaire-integrated light sensors for daylight harvesting; and a ceiling-mounted occupancy sensor for automatic shutoff.
Another interesting application for integrated control is stairwell lighting, which is typically operated continuously, although research suggests the average stairwell is occupied for less than 5 percent of the day. A growing number of stairwell-lighting products feature occupancy sensors that switch or dim from full output (e.g., 10 footcandles) during occupancy to a lower level (e.g., 1 footcandle) when the stairs are unoccupied.
While many manufacturers now offer an integrated control option, at least one lighting-controls company, Lutron, has a line of fixtures with dimming ballasts and other control options automatically pre-installed, including high bay, linear recessed, CFL and LED downlights, videoconferencing, and stairwell retrofits.
Expanding Wireless
With luminaire-integrated controls, sensor placement is limited by fixture placement, and creating control zones for multiple lights is tied to hardwiring between the sensor and the luminaire controllers. For applications requiring greater flexibility, some manufacturers offer wireless controls. Such sensors, switches, and dimmers are placed where needed, and send signals to receivers or transceivers and controllers that are pre-installed in the fixture. These input devices can communicate with multiple fixtures, allowing the creation of control zones without hardwiring.
A number of companies already offer wireless control as an option for their luminaires. Hubbell Outdoor Lighting’s system offers the Hubbell Building Automation’s wiHUBB System, which consists of a self-organizing, self-healing mesh network of wireless luminaire-integrated receivers–controllers, occupancy sensors, light sensors, and switches.
LaMar Lighting also offers an integrated wireless-control system, Control-Smart, as an option with its fixtures. These wireless controls are based on the EnOcean standard, making the switches and sensors self-powered—that is, they are able to operate without the need for batteries.
Lutron puts wireless technology to use with its PowPak stairwell-retrofit luminaire, which contains a digital-dimming ballast, preprogrammed with occupied and unoccupied light levels that can be changed in the field. The luminaire accepts signals from a wireless occupancy sensor, and raises or lowers output accordingly. This allows the sensor to be placed wherever it is needed in the stairwell, avoiding blind spots. Additionally, the sensor not only raises the output of the luminaire that covers the occupied portion of stairwell, but also the output of the luminaire on the floor above and the floor below, providing a relatively seamless experience for occupants.
Solid-State Lighting Control
Lighting-control outputs are highly compatible with solid-state lighting. LED luminaires are instant-on, and frequent switching does not decrease diode life, making them suitable for use with occupancy sensors. Dimming not only saves energy in a linear relationship between light output and power across most of the dimming range, but it can also extend the lives of these products.
LED systems are compatible with basic control strategies such as manual dimming, occupancy sensing, time scheduling, and daylight harvesting. Advanced strategies such as lumen management, high-end trim tuning, and demand response can also be implemented, taking advantage of solid-state lighting’s inherent compatibility with digital controls. LED luminaires can monitor characteristics such as occupancy, light level, ambient temperature, product light-output and life, and system faults, and can subsequently respond in preprogrammed ways using onboard logic to optimize energy use and maintenance.
Digitally addressable, the LED luminaire can network with control devices and other fixtures, enabling centralized control and information feedback. One interesting example of integrated LED control is Lithonia’s RTLED recessed volumetric-distribution fixture, which contains embedded nLight control technology from fellow Acuity brand Sensor Switch. The luminaire dims to 5 percent using zero-to-10V DC control; a fully operational lighting and control system can be constructed by simply connecting the luminaires. Additionally, the nLight controller underdrives the fixture to deliver constant light output over the product’s rated life, in addition to saving energy. Each luminaire tracks its own operating hours and provides a visual indicator that it has reached the end of its service life.
Digital Lumens also offers intelligent, industrial high-bay LED luminaires with a built-in occupancy sensor, light sensor, an onboard controller that tracks power use and occupancy, and wireless mesh networking.
NXP (formerly a division of Philips) offers the GreenChip, a technology built into solid-state and compact fluorescent lighting that gives each luminaire or lamp its own IP address and wireless ability, enabling new ways to control lighting and manage energy use.
The Sylvania Ultra LED BR30, an energy-saving 12W replacement for 65W incandescent BR30 lamps, features integrated dimming control, operated using a handheld remote that can be used to recall lighting scenes from a network of up to 50 lamps.
The ultimate solution, though, is integrated networking, in which DC devices such as LED luminaires and lighting controls are served by a low-voltage cabling system that forms both a communication network and power grid. This simplifies the wiring and increases the efficiency of the system. Luminaires and controls connect to the power system by using snap connections to access power and communication. Redwood Systems offers a fully developed proprietary solution, while the EMerge Alliance is promoting building DC power standards and compliant solutions from its member companies—which includes Crestron, Leviton, Sensor Switch, WattStopper, and a number of lighting manufacturers.
Lighting controls have become a critical part of today’s lighting design. Manufacturers offer a wide range of fixture and controls solutions—from luminaire-integrated sensors and controllers, to complete hardwired and wireless control systems, to sophisticated embedding control capability into the actual light source. And as clients and projects continue to call for greater functionality in order to provide higher-quality illumination and energy savings, these solutions will only become more commonplace and continue to evolve in capabilities.
Craig DiLouie, principal of Zing Communications, has been a journalist, educator, and marketing consultant in the lighting industry for more than 20 years.