Lighting systems are increasingly incorporating network interfaces and sensors, and metamorphosing into data collection platforms that can implement advanced adaptive lighting strategies, enabling data-driven lighting energy management in buildings and cities, and can deliver other potentially high-value services, ranging from space utilization and office scheduling to asset or inventory management and many other functions. Although such connected lighting systems (CLS) might enable dramatic improvements in the energy performance of lighting and other energy-intensive systems or services, at this early stage in their development, that potential is limited by significant fragmentation of the underlying technologies and interfaces. As a result, today’s CLS are generally not natively interoperable, meaning they cannot be assumed to work well together or be capable of exchanging the data that they collect with one another or other systems.
The main goal of this series of studies is to discern and document the state of CLS interoperability in this early stage, multi-vendor, multi-technology, and multi-business-model landscape. Although a number of industry consortia are developing frameworks or technologies that facilitate more native interoperability, at present these efforts are either incomplete or immature, do not support lighting applications sufficiently, or are not adopted by a significant number of lighting manufacturers. At present, interoperability between CLS offered by different vendors – or, in some cases, even between different solutions from the same vendor – is facilitated primarily through application programming interfaces (APIs), or not at all.
This initial study, which focuses on interoperability as realized by the use of APIs, explores the diversity of such interfaces in several CLS; characterizes the extent of interoperability that they provide; and illustrates challenges, limitations, and tradeoffs that were encountered during this exploration. More specifically, the system architectures and API structure, nomenclature, and information models were characterized; the development of a common integration platform was investigated; and two real-life use-cases were simulated to illustrate the relative effort required to use APIs to enable new features and capabilities facilitated by information exchange.
Although APIs and web services enable a certain level of interaction between heterogeneous systems on the Internet, they require some effort and skill to use effectively and efficiently, and they do not serve all interoperability goals. Integrating multiple CLS through APIs does not result in a homogenous system; at best it yields a common user interface and experience. However, effectively abstracting any underlying heterogeneous characteristics that do not serve the end user in some tangible way can require a significant amount of integration work. Managing what functionally remains a distributed system at one or more interoperability layers can be challenging and can require substantial effort. Differences among network protocols, device representations, and access policies that affect performance must be understood, addressed (if possible), and managed – not only initially, but over the course of hardware, firmware, and software upgrades. Asynchronous data flow can lead to latency issues and bandwidth bottlenecks. Integrated system failures and performance issues can be very difficult to debug and subsequently isolate and mitigate, without taking down the entire system. Implementing mechanisms and policies that maximize reliability and quality of service while still allowing the integrated system to scale and simultaneously continue to deliver end-use functionality requires advanced developer skills. Further, at present, system integrators may have to navigate API implementations that are poorly or insufficiently documented, or have not been well- exercised, rendering them immature or, in some cases, unusable.
APIs are becoming increasingly available for connected lighting systems. The APIs provided by current market-available CLS vendors can be utilized to facilitate enough interoperability between lighting systems to enable lighting-system owners and operators to implement some level of multi- vendor integration and some remote configuration and management services, as well as some adaptive lighting strategies. However, in many instances, API inconsistency and immaturity unnecessarily increase the effort required to implement these services and strategies, and reduce the value and performance that they deliver. API developers are encouraged to provide up-to-date and comprehensive API documentation and to support the efficient identification of bugs. Further, they should explore and attempt to implement common approaches to naming and organizing resources, as well as common information and data models – which are key to both minimizing the effort required to integrate heterogeneous systems and enabling functional, high-value use-cases.
The U.S. Department of Energy (DOE) intends to support improved interoperability by continuing to investigate approaches to realizing interoperability between CLS from different providers, as well as between connected lighting and non-lighting systems. Without more effective, efficient, and, ultimately, native interoperability, connected lighting technologies may see limited deployment, unable to go beyond simple connectivity and to fulfill their energy efficiency and transformative potential. Lighting industry stakeholders and system integrators are encouraged to provide DOE with investigation recommendations and to propose collaborations that might best contribute to realizing these goals.
You can read the entire study here.