Interoperability Is Key To Connected Lighting Systems

Sensors Insights by James Brodrick

One of the many ways in which the advent of LED lighting is revolutionizing the concept of lighting is by making it feasible – both technologically and economically – to create connected lighting systems. Because of their microelectronic nature, LEDs lend themselves quite well to integrating sensors, network interfaces, and other functionality that can significantly reduce the energy consumption of lighting and other building systems, and also bring other benefits.

But in order for connected lighting to succeed in the long run, there must be sufficient interoperability. System performance is dependent not just on constituent device capabilities, but also on the ability of those devices to work together. Interoperability enables different devices, applications, networks, and systems to exchange data and thereby work better together. For users, it reduces the risk of device or manufacturer obsolescence, as well as the risk of having limited hardware, software, data, and service choices. It can also improve system performance by facilitating multi-vendor competition, reducing the cost of incremental enhancement, enabling greater data exchange, and encouraging service-based deployment of complex technology.

Traditionally, there’s been little to no interoperability in market-available lighting-control devices and systems, as manufacturers have focused on developing and promoting their own proprietary technologies or unique implementations of industry standards. Interoperability is a key and much-discussed topic in these early days of the Internet of Things (IoT), and achieving it requires industry to agree on common platforms and protocols that enable the transfer of usable data between lighting devices, other systems, and the cloud.

A number of consortia are working to ensure viable interoperability, such as the Open Connectivity Foundation, the TALQ Consortium, oneM2M, Bluetooth SIG, the Industrial Internet Consortium, and the ZigBee Alliance. As with the development of computing and IT technologies, these groups are taking different approaches or addressing different parts of the puzzle. But at the moment, there remains little interoperability in commercially available connected lighting systems.


A Test Bed

The U.S. Department of Energy (DOE)  has created a connected lighting test bed (CLTB) to characterize the capabilities of connected lighting systems. The results will increase visibility and transparency on how well devices and systems work, and will create tight information feedback loops to inform technology developers of needed improvements related to interoperability and other focus areas the likes of energy reporting, configuration complexity, cybersecurity, and key new features.

The U.S. Department of Energy’s Connected Lighting Test Bed
The U.S. Department of Energy’s Connected Lighting Test Bed

The CLTB has infrastructure that enables the efficient installation of indoor and outdoor lighting devices. Two ceiling grids are available for installing indoor lighting luminaires. The height of each grid is vertically adjustable, to enable easy installation and set varying luminaire heights.

The grids have plug-and-socket interfaces to enable easy electrical connections, and circuit-level power and energy metering in the electrical panels that serve them. The CLTB also has dedicated infrastructure for street lighting luminaires – again, with plug-and-socket interfaces to enable easy electrical connections.

To enable the testing of multiple devices and systems, the CLTB includes a software interoperability platform that allows installed lighting devices and systems that are not natively or fully interoperable to be capable of exchanging data with each other. Multiple indoor and outdoor connected lighting systems have been incorporated into the software interoperability platform and made available for CLS and other studies.

Initial efforts to integrate connected lighting systems in the CLTB have brought valuable insight into current interoperability capabilities and limitations. DOE has encountered application programming interfaces (APIs) with a wide range of architectures and data models that support varying capabilities and use cases. A first DOE study on CLS interoperability is focusing on characterizing the APIs available for a number of indoor and outdoor systems, with the goal of highlighting what’s currently possible, tradeoffs, and lessons learned, as well as informing collaborative efforts toward improved interoperability.

Another study is testing a variety of power-sourcing equipment and powered devices in Power over Ethernet (PoE) connected lighting systems, to evaluate energy use reporting accuracy and isolate sources of error. Background has been provided on various PoE technologies and architectures, existing standards and specifications, and recommendations for characterizing and reporting energy consumption. Testing will soon be underway to quantify energy losses in PoE cabling, exploring the impact of cable characteristics and installation techniques, and verifying the usefulness of emerging industry recommended practices.

A cybersecurity characterization capability is also being established in the CLTB in collaboration with Underwriters Laboratories (UL) and a variety of technology partners, as part of their effort to develop a standardized test method for cybersecurity vulnerabilities. DOE will share test results with UL and other Industrial Internet Consortium partners, who in turn are supporting the DOE capability with hardware and software, as well as test methods and general cybersecurity expertise. A study is also underway to characterize the accuracy of energy consumption reported by streetlight controllers, in collaboration with National Grid, TESCO, and Georgia Power.


It’s All About Sharing

Why focus on interoperability? One reason is that it facilitates the ability to integrate best-of-breed components which, in lighting systems, includes sensors, controllers, software, etc. Interoperability can also facilitate the ability to more easily modify and improve an existing system as its owner and occupant needs become increasingly clear. It helps manage the risk of component – and manufacturer – obsolescence; there are many new players in this field, and not all of them will still be around in five or 10 years, so that’s a risk that needs to be addressed in one way or another.

But even more importantly, as lighting infrastructure becomes more connected, interoperability will facilitate the sharing of data between all lighting and connected non-lighting systems. Interoperable devices can not only share the data they generate; they can also use data that were generated elsewhere. This sharing of data can help lighting systems perform better by adapting the lighting to existing conditions, and can also facilitate non-energy benefits – not only for the lighting system, but for other systems as well. This significantly increases the value of those lighting systems.

To deliver interoperability in this way, much needs to be agreed upon and defined. When talking broadly about interoperability using a simplified model, there are three “layers” that need to be defined for full interoperability:

  1. how data are created physically
  2. how data are routed around
  3. how data are understood

With the present trend toward interconnected systems, there’s not likely to be just one lighting or building communication technology or protocol that, by itself, will predominate and facilitate interoperability. Nor will there likely be one master command center for a building or outdoor space. Building and lighting systems will instead probably look a lot more like IT systems, with devices and systems connecting to a communication network, exchanging data, and making many decisions at more proximal locations including, in some cases, at the luminaire level.

The interoperability of connected lighting systems is still in the early stages. As it progresses, the full benefits of connected lighting – including increased energy savings – will start to be realized. To facilitate the process, we need more and better conversations about this topic of growing importance, which is the purpose of DOE’s connected lighting studies.


About the author

James Brodrick is the manager of the U.S. Department of Energy Lighting program, directing solicitations, portfolio management, strategic planning, and quality performance. Drawing on extensive technical knowledge, Dr. Brodrick has designed a comprehensive DOE national strategy for driving solid-state lighting (SSL) advances. The DOE SSL program encompasses a wide range of active R&D projects that accelerate technology innovation and breakthroughs in efficiency and performance. In addition, technology application R&D projects monitor SSL technology advances and provide field and laboratory evaluations of emerging products, particularly advanced lighting systems and controls. In contrast to a single project focus, technology application R&D projects address broad issues related to technology performance, with a view that spans the entire industry and induces technology improvements faster than might otherwise occur.