Solid-state lighting is opening up new possibilities for smart buildings and smart cities. Everyone is buzzing about the Internet of Things (IoT) and the possibilities of remote provision and management of lighting systems. The biggest challenge has been communications. LEDs already have embedded programmability to control intensity, hue, temperature, and other characteristics – what we call clever lighting. For intelligent lighting you need communications as well. There are multiple lighting communications and control standards, including DALI, ZigBee, BACnet, Z-Wave, and others, but they aren’t interoperable. IoT offers a common platform for communications. This article will discuss two possible strategies for implementing smart lighting – one wired using Ethernet and the other wireless using Bluetooth mesh. Each approach has benefits in terms of efficiency and reducing energy consumption.
Everyone is talking about smart lighting but who is doing something to make it a reality? There is technology available to add intelligence to LED lighting systems, but the real question becomes how do you connect the luminaires? There is no one dominant standard for lighting communications, and no one wants to commit to the wrong technology. After years of “nearly there” promises, there are finally some open standards approaches such as Bluetooth Mesh and Ethernet that provide lighting controls today and make an ideal platform for smart lighting or the Internet of Things (IoT) in the future.
Energy savings are usually the first benefit achieved with smart lighting. According to the U.S. Energy Information Administration, 17 percent of the energy used in commercial buildings goes to lighting (see Figure 1). Commercial building managers have been saving energy by switching to LED; overall electricity consumption due to lighting dropped from 38 percent to 17 percent between 2003 and 2012. Gartner predicts that energy savings from smart lighting could ultimately be as much as 90 percent.
But the potential benefits only start with energy savings. Having a common standard for smart lighting systems also opens up a host of possibilities for both building automation and smart cities. In any building, light fixtures are the most prevalent piece of electrical equipment, outnumbering wall sockets. The same is true for city streetlights. Imagine the possibilities of equipping those lights with sensors to monitor conditions in the immediate area as well as providing centralized lighting controls. Lighting moves from illumination to a value add system.
To make this shift you need both lighting intelligence and control. Intelligence can be incorporated into the LED luminaires themselves, but control has to be both distributed and centralized. Let’s start with a look at smart luminaires before we review the challenges of adding communications.
From clever lighting to smart lighting
Solid-state intelligence is the first step toward smart lighting systems. Embedding programmability in LED fixtures makes it easy to control the LEDs at the luminaire level, adjusting for characteristics such as hue, light intensity, dimming, and energy consumption. We have labelled these programmable LED fixtures “clever” lighting; luminaires that can be individually programmed at the factory, when they are installed, or when they need to be adjusted over their lifetime. To become smart or intelligent lighting, you only have to add communications.
When you say “lighting control” to most people they think of a simple dimmer switch. For some time now, we have had four basic types of lighting controls:
- Manual – The simplest lighting controls are an on/off switch or a manual dimmer switch.
- 4. Light harvesting – Using light sensors to detect ambient light and adjusts room lighting accordingly, e.g. less artificial lighting is needed for a room with windows on a sunny day.
All of these strategies offer the simplest type of lighting control. Using programmable LED components allows you to customize the luminaires to a limited degree but control is still highly localized, usually to just a single room. It’s less expensive to install, but offers limited functionality, makes adding or changing luminaires difficult, and presents a single potential point of failure.
Intelligent lighting uses a centralized building automation control system. It can be initially more expensive to install but offers many more long-term benefits. For example, you not only gain control of energy management for the entire infrastructure, but you can tune specific fixtures or an entire space from a single location. Centralized lighting controls also provide more detailed data about energy consumption and luminaire performance to monitor energy savings and can even issue an alert when a light is ready to fail.
Now consider the possibilities of using intelligent lighting as part of an overall building management platform. Sensors can be placed anywhere there is a light fixture, and those sensors can provide information for applications such as HVAC, motion detection to prevent intruders, smoke detection, triggering an alarm, activating automatic door locks, providing emergency lighting, monitoring air quality, etc. You even can extend this model to entire municipalities using sensors mounted in streetlights can be used to monitor traffic and control traffic lights, monitor weather conditions, and light specific areas on demand, as well as managing energy consumption.
The sensor may be programmable – clever – and can be adapted for a variety of uses but they still need to communicate with the central controller to be considered smart lighting. But what is the best communications strategy and how do you ensure different communications protocols are interoperable?
Enter the Internet of Things
The Internet has become the common communication platform for almost everything, including machine-to-machine communications. The IoT promises to revolutionize monitoring and control of devices, including lighting. In fact, lighting provides the ideal skeleton for an IoT infrastructure:
Light fixtures are installed at regular intervals and can readily be equipped with IoT sensors.
Building lighting system connect to a single, stable power source; a potential central control point.
Light fixtures are more prevalent than any other electrical system in a commercial building, including power outlets.
Sensors mounted in luminaires can carry all sorts of data traffic back to a central control console. Since lighting is ubiquitous it’s ideal for IoT. However, Internet Protocol (IP) controllers will have to find a way to interoperate with established lighting control and communications standards such as:
DALI – The Digital Addressable Lighting Interface (DALI), which is growing as one of the preferred standards for digital lighting controls including LEDs.
ZigBee – ZigBee, a wireless standard that provides control over various types of devices, including lighting, and has been endorsed by the Connected Lighting Alliance.
TALQ – Designed for outdoor lighting systems as a common management software standard.
These are just some of the most popular lighting communications standards. These standards are not designed to work together and they also are not mutually exclusive. Rather, they tend to interoperate as hierarchical standards (see Figure 2). In building automation, for example, controls are layered using different control protocols at each layer. BACnet, the protocol for integrating building automation, provides the primary control bus for automation controls, but secondary layers of communications support other protocols for machine-level communications.
IoT will likely evolve in much the same way, as a common aggregation platform for other control protocols. To support IoT, the existing lighting standards and luminaires need to be compatible and interoperable.
Bluetooth Mesh Brings Wireless Connectivity
In addition to interoperable standards, smart lighting solutions are going to need a connectivity platform. Rather than rip out and replace existing lighting systems, smart lighting will likely be built on wireless standards such as ZigBee, Wi-Fi, and Bluetooth Mesh. We believe that Bluetooth Mesh in particular offers some interesting possibilities for smart lighting applications.
Bluetooth Mesh was created in 2015 and adopted as a networking standard in 2017 as an extension of the Bluetooth Low Energy (BLE) radio standard. Bluetooth Mesh provides many-to-many networking for large-scale device networks, such as asset tracking, wireless sensor networks, and building automation. It is especially well-suited for IoT networks that require hundreds or thousands of devices to communicate using small packets of device data.
For smart lighting applications, Bluetooth Mesh offers a number of advantages:
Industrial-grade networking – Bluetooth Mesh has been tested and proven to be a true, industrial-grade solution that offers reliability, scalability, and security for commercial buildings and factory automation.
Proven interoperability – Well-defined open standards make it easier to develop products that truly interoperate. Bluetooth Mesh ensures interoperability by offering:
i) Full-stack implementation;
ii) Interoperability at the core of the specification; and
iii) Tested interoperability tools and processes.
Mature technology – While Bluetooth Mesh itself is still relatively new, Bluetooth wireless connectivity has been around for some time and has been embraced by most vendors seeking a wireless solution.
Easy Configuration – Most of us carry a smartphone which has integrated Bluetooth, making it only a free app away from controlling lighting.
Bluetooth Mesh also helps with web integration for Internet controls. And even though the Bluetooth range is typically 200 meters, Bluetooth Mesh provides scalability well beyond a single Bluetooth transmission.
Bluetooth Mesh Under the Hood
Bluetooth Mesh operates as a “flood network” where every incoming packet is shared with every outgoing link so the data proliferates across the entire mesh.
Messages can be up to 384 bytes long but most messages fit in a single 11-byte segment. Each message starts with an opcode of one byte (for special messages), 2 bytes (for standard messages) or 3 bytes (for vendor-specific messages). Machine-to-machine communications tends to require smaller date packets so Bluetooth mesh can readily handle the data traffic.
Each message also has a source and destination address, and a sequence number to prevent replay attacks. And each message is encrypted and authenticated for security. There are two keys to secure Bluetooth Mesh messages: 1) network keys that are allocated to a single mesh network and 2) application keys that are specific to an application function, such as turning on a light as opposed to reconfiguring a light.
One of the advantages of using Bluetooth Mesh for smart lighting is it can support two-way communications. This means the same mesh infrastructure can be used to provision smart lighting solutions and monitor luminaire performance.
As a mesh infrastructure, Bluetooth Mesh also is self-healing so you can add or remove devices as needed without any system reprogramming. If a device fails or the signal is blocked, the mesh simply reroutes the data through other nodes. Another advantage to using an open standard such as Bluetooth Mesh is that it is easier to ensure compatibility. The standard is well-defined so building and testing compatible products is fairly easy, and as long as the products are SIG-qualified Bluetooth Mesh, qualified by the Bluetooth SIG.
Bluetooth Mesh is perfect for lighting controls as well as other building systems. Once Bluetooth Mesh sensors are installed in luminaires they can be adapted for multiple functions. For example, the same Bluetooth Mesh sensors in the luminaires can be used to detect temperature, humidity, and air quality to adjust HVAC.
The Promise of Power over Ethernet
Wireless networking may be the best solution for lighting retrofits, but what about new construction, or areas that do not want to introduce additional wireless networking? As smart lighting starts to take hold, wiring lighting using 10BASE-T Ethernet cable could offer a better approach for both power and lighting controls.
When it comes to new construction, consider replacing conventional power with 10BASE-T Ethernet cable. The computer network can be used to power and manage the building’s lighting infrastructure and lay the groundwork for other connected devices. It’s a matter of which comes first, IoT or smart lighting. If you start with the computer network, then it’s the smart lighting that actually delivers IoT.
First, let’s consider the specific advantages of adopting Power over Ethernet (PoE). As specified in the IEEE 802.3 standard, both power and communications data are transmitted across the same Category 6 network cable, which is connected directly to the networked devices including DC-powered solid-state luminaires. Given the gains in lumens per watt improvement with LEDs, while the PoE may not have been enough to power fluorescent luminaires, it is certainly sufficient to power LEDs, which eliminates the need for less efficient AC-to-DC conversion. Since the DC power is connected directly to the LED circuitry no drivers are needed.
The decrease in energy from direct-to-DC power represents a substantial energy savings. A study by Carnegie Mellon University estimates that savings are about $2,000 (US) per year, and that jumps to $5,000 per year when you add in solar power support. Plus, you get additional savings from the greater longevity of LED luminaires; typically, an LED lasts 50,000 hours as opposed to 1,000 to 2,000 hours for incandescent lights and 5,000 to 10,000 hours for compact fluorescents.
With a direct network connection to the LED components you also get complete control over the LED luminaire. PoE provides integrated communications with all the networked luminaires to simplify commissioning and software upgrades as well as light management. For example, the facility’s network can measure, monitor, and control all the lighting nodes in the building’s network, including managing power consumption, colour temperature, and light levels. You can even moderate the heat from each lighting unit and detect when an LED is ready to fail.
Once you have installed building lighting powered via Ethernet you have a computer network that can be adapted to use IoT to manage the entire building. Installation is easy; all you do is plug your Ethernet cable into the RJ-45 jack for each sensor-equipped light fixture. The sensors in the luminaires then can be programmed to collect data on ambient light, humidity, temperature, humidity, room occupancy, and other conditions, and that data can be used to control HVAC, window blinds, etc. PoE is a great way to “future-proof” your building at the same time it opens up a wide range of IoT possibilities.
What’s Holding Back IoT
Installing more IoT-enabled sensors doesn’t necessarily mean that existing lighting control systems have to be replaced. As IoT-enabled lighting fixtures are being retrofitted, IP-based controls will become more prevalent, but there will still be legacy lighting control standards. Control protocols such as DALI and BACnet can operate concurrently with IoT.
With DALI, for example, up to 64 luminaires can be connected into a single network to control individual light fixtures or groups. DALI offers more granular control of light dimming and other characteristics, such as dimming from 0-10V or dimming to off. However, IPv6 can still be used as a common communications protocol for an IoT infrastructure, with layers of communications to support and interconnect existing systems such as DALI.
What is going to delay IoT adoption for lighting control isn’t standards incompatibility or technical issues; delays will come from timing. IoT certainly promises to solve a number of integration and automation issues, but most of the luminaires installed today will be in service for another five to 10 years. Until they fail there is no reason to replace them with new smart luminaires. The commercial lighting market has a mature supply and deployment strategy with plenty of “dumb” luminaires in the pipeline. The industry clearly isn’t ready to start installing smart luminaires that can support IoT.
It’s obvious that the first smart luminaires to make their way into the channel will have wireless support such as Bluetooth Mesh for retrofit. Sales of LED luminaires for retrofits are expected to make up 50 percent of the LED lighting market through 2024, which isn’t surprising when you consider that half of commercial buildings in use today are more than 60 years old.
Hard-wired intelligent lighting, such as that required for PoE, will likely become part of new construction, but will be slower in coming. There has only been 7-8 percent new construction in overall commercial space since 2000. However, the potential energy savings and granular building controls from smart Ethernet lighting is eventually going to drive demand. For now, retrofitting fluorescents with “dumb” LED luminaires is already delivering substantial energy savings without the benefit of smart lighting controls.
For smart lighting systems to gain market momentum, manufacturers are going to have to take the lead by offering LED luminaires equipped with IoT-ready sensors that are simple to install and offer a relatively fast ROI. With smart light sensors already in place, installers can add intelligence via wireless or hard-wired connections at some future date. Once two-way communications are in place we will start to see the real returns on smart lighting, and the evolution of new IoT-enabled buildings.
Russ Sharer is Vice President of Global Marketing and Business Development for Fulham Co., Inc., is a business leader with over 25 years of experience in B2B marketing and sales, including successful software and network equipment start-ups. Fulham is a manufacturer of innovative and energy-efficient lighting sub-systems and components for lighting manufacturers worldwide.