According to the U.S. Department of Energy (DOE), about 160 million lamps operated in the building exterior, parking area and roadway lighting markets in 2010. Building exterior made up 39 percent of these lamps, parking 33 percent and roadway 28 percent.
Building exterior (facade and grounds) lighting is considered curfew lighting, meaning it does not have to operate all night. Area and roadway lighting is considered dusk-to-dawn lighting, meaning light must be available all night for safety and security reasons.
In 2010, LED technology achieved negligible penetration against high-intensity discharge (HID) lamps. LED outdoor lighting now offers efficacies nearly as high as high-pressure sodium while providing white light, long life, controllability and superior optical control. These benefits are driving adoption in both new and existing construction, where outdoor lighting is now a very popular option for LED retrofits.
By 2015, the LED achieved an estimated 19 percent penetration of the installed lighting base in the outdoor stationary market. The DOE predicts it will increase to 57 percent by 2020 and 79 percent by 2025, generating significant energy cost savings. One of the advantages of LED over HID is its superior controllability, and lighting controls can contribute significant additional savings and other capabilities.
Traditionally, an astronomical time switch or photocell automatically turned outdoor lighting on and off at the circuit level. The time switch operates according to a preset schedule that takes into account changing sunrise and sunset times. The photocell responds to daylight.
LEDs’ instant-on operation and ability to dim offer two control capabilities. First, occupancy sensing can be installed to extinguish or otherwise reduce lighting when it is not being used after hours. Second, lamps can be dimmed based on a program. Coinciding advances in wireless intelligent control further allow each luminaire to become a control point in a network. Using this capability, operators can remotely manage all outdoor lighting while collecting data useful for energy analysis and maintenance. By installing additional sensors, cameras or audio, operators can collect other data and gain added capabilities, the foundation of a smart city.
The proliferation of LED outdoor lighting resulted in a new standard interface that unlocks the full spectrum of control capabilities. Traditionally, the industry was served by standard twist-lock photocontrols featuring three pins that turned the luminaire on or off. In 2014, the American National Standards Institute (ANSI) C136 Roadway Lighting Committee, in cooperation with the National Electrical Manufacturers Association, published the ANSI C136.41 standard, which designates a seven-pin receptacle and photocontrol for outdoor area lighting. The three core pins are identical to the old standard. Two of the four new low-voltage pins are used for dimming while the other two can be used for occupancy sensing, power monitoring, two-way communication or other use.
The majority of states maintain commercial building energy codes based on either the ANSI/ASHRAE/IES 90.1 energy standard or the model International Energy Conservation Code (IECC). The 2010–2013 versions of 90.1 and the 2012–2015 versions of the IECC require automatic control of outdoor curfew and dusk-to-dawn lighting as follows, with some exemptions.
A combination photocell/time switch must control curfew lighting. The photocell turns the lighting on. The time switch turns it off at a set time after-hours when no longer needed. The lighting must turn off between midnight or business closing (whichever is later) and 6 a.m. or business opening (whichever is earlier), or on whatever schedule the authority having jurisdiction allows.
A photocell must turn dusk-to-dawn lighting on and off. In addition, a control must reduce lighting power by at least 30 percent. This can be accomplished using either scheduling or occupancy sensing. If scheduling is used, the lights must be reduced from midnight or within one hour of end of business operations (whichever is later) until 6 a.m. or business opening (whichever is earlier). If occupancy sensing is used, the lights must be reduced after no activity is detected for about 15 minutes.
The 2016 version of 90.1 goes even further. Dusk-to-dawn lighting must be capable of reducing power by at least 50 percent, up from 30 percent in the previous versions. Additionally, certain outdoor parking area lighting (greater than 78 watts [W] and a mounting height of 24 feet or less) must be reduced by at least 50 percent using an occupancy sensor after 15 minutes of inactivity, and each sensor must be limited to controlling up to 1,500W of lighting power.
A sample sequence of operation follows for dusk-to-dawn luminaires that do not require full output during all operating hours. The photocell activates the luminaire. At a certain time of night, a time-based controller, which may reside at the luminaire or a remote panel, reduces output across all luminaires. A passive-infrared occupancy sensor then raises or lowers light and power based on occupancy.
Energy codes provide a baseline of energy efficiency for new construction and renovations but may also serve as a best practice for energy-saving upgrades in existing construction. Despite significant energy savings potential, new controls are sometimes difficult to justify as a stand-alone upgrade. However, integrating controls into an LED upgrade can produce an economically viable solution, especially when utility rebates are applicable.
Incorporating intelligent control and wireless communication presents additional capabilities. Intelligence entails use of a microprocessor-based lighting controller for decision-making. By putting a controller in each luminaire, the luminaire becomes capable of operating independently. For example, its operating schedule and degree of lighting reduction could adjust based on the application; luminaire output could be brightest at sunrise/sunset and automatically reduce the rest of the night.
Wireless communication eliminates wiring from controller networking, making networking more economical. This allows remote calibration, programming and zoning of luminaires both individually and as groups. Another potential capability is measuring and monitoring that produces data usable for energy management, maintenance and security.
For example, the system could alert operators to a fault or failure, such as a luminaire operating during the day, while showing exactly where the problem is occurring. The wireless system is typically based on a series of gateways that manage information from nodes embedded or mounted on the luminaires. Operators access these gateways using software. Most networks use a mesh—or tree—architecture, which features repeating and self-healing nodes. A variety of protocols and methods, such as ZigBee, are used.
Due to the many types of available systems and approaches, be sure that a selected system has all the needed features.
The ultimate expression of the potential inherent in intelligent wireless control is the “smart city.” Just as the Internet of Things (IoT) offers exciting potential to transform living and workspaces, LED lighting, coupled with sensing, connectivity and software, enables similar possibilities for cities.
Smart cities include a network of systems that is programmable, automatically responds to environmental conditions and collects data. Buildings, information technology and energy systems may be integrated. It is an IoT strategy applied to cities.
Applicable energy systems include lighting, automation, life/safety, telecommunications and facilities management. All run on ethernet/IP to enable human/system/object interaction, response and reporting.
The miniaturization of microprocessor technology has resulted in the ability to embed intelligence and sensors/cameras in lamps and luminaires. Lighting is ubiquitous in buildings, presenting an ideal platform for sensors using a retrofit to LED lighting. Similarly, public street and area lighting is common in urban outdoor areas. Manufacturers such as GE, Osram, Philips and Sylvania are actively selling smart-city solutions.
“Due to their digital nature, these controls are inherently compatible with LEDs,” said Todd Smith, director of engineering and solution development, Sylvania Lighting Solutions. “Therefore, LEDs have the potential to be the primary infrastructure through which smart city networks are delivered.”
A smart city solution might include a collection of buildings, all outdoor spaces, or both. Typically, for outdoor lighting, communication is wireless. The streetlight may also host wireless signal boosters and networking hubs.
The three major capabilities of the lighting platform include light, management and data. The LED luminaires must provide quality lighting while reducing energy costs by up to 50–70 percent; it is 80 percent when paired with controls. Next, the luminaires are connected within a programmable and manageable network, allowing sophisticated control strategies and remote configuration. Luminaires can turn lights on and off or dim them, individually or in groups, based on inputs such as time of day, daylight or occupancy. Finally, the luminaire may incorporate additional sensors to capture additional data for analysis or alerts. Data is delivered to the cloud or a server for retrieval.
Measurable conditions include lamp/luminaire status, power and energy consumption, occupancy/motion, relative humidity, temperature, daylight, air quality, snow accumulation, smoke, radiation and noises such as gunshots. City officials can use this data for both analytics to improve process efficiencies and for alerts to facilitate efficient response.
For example, the system could detect a lighting or power outage, gas leak or car accident and immediately alert city officials, improving emergency response times. Geolocation-based alerts identify the exact site of events.
Another potential capability is integration of Wi-Fi access points, which can enhance city services while providing a valuable service to city residents and visitors. Manufacturer software may offer a broad range of capabilities, though extended capabilities may require custom software.
“Capabilities of a smart city are endless, and, oftentimes, cities can work with any of a wide variety of application developers to deliver better asset management, service delivery, citizen safety or municipal operations,” said James Benson, GM Global Marketing, Current, powered by GE, Intelligent Cities. “Once the city has the physical infrastructure and open/scalable digital framework in place, the sky is the limit with regard to what their smart city can achieve.”
While interconnected streetlights sound complex, installation may be fairly straightforward. The control node plugs directly into the luminaire receptacle based on an ANSI-standardized connection. No additional wiring is required. Also, the EC may have the opportunity to help maintain the system.
System planners must accommodate potential problems that may occur during operation, such as noise on the line in the case of powerline communication and occlusions and frequency of data transmission if wireless.
Availability of 24/7 power to the light pole is another concern. Intelligent streetlights with embedded sensors and communications require power during the day; shutdown of power to the network can be problematic.
“A well-designed smart city infrastructure can enhance services and business opportunities, improve safety and boost collaboration between the city, its citizens and businesses and continue to do so for decades to come,” said Susanne Seitinger, global subsegment manager, Philips Lighting, professional systems. “To achieve this, decision-makers should make sure the following questions can be answered satisfactorily: Is it scalable? Is suitable connectivity available? Are the right IT staff available? Is it sufficiently secure? Can all the elements be integrated successfully? Is it accessible?”
To broaden adoption, various lighting-industry players formed the TALQ Consortium to develop standardized, interoperable interfaces connecting streetlighting networks with various hardware and software vendors. This enables open systems using interoperable solutions. The Outdoor Lighting Standard was completed in 2016, with the first compliant systems expected to be rolled out this year. For more, visit www.TALQ-Consortium.org.
With the flexibility inherent in LED and controls, outdoor lighting can deliver satisfying energy savings. With intelligence, communication and the ability to collect data, it can deliver sensing, decision-making, control and prediction. ECs that become educated on the technology may position themselves for these new opportunities.