Practical specification
Today’s lighting controls can be separated into two categories—centralized and distributed.
Centralized systems, as the name suggests, rely on a centralized controller to provide the intelligence required for managing the lighting within a space. Distributed systems, in contrast, work by distributing the control intelligence out to the device itself. In the author’s experience, the industry is moving toward distributed systems.
Centralized systems require messages from one device to first go to a controlling master or gateway before the signal can get to the target device. In this scenario, every communication between two non-master devices includes an extra step, or fault possibility. Distributed systems remove the single point of failures inherent in any centralized-control architecture and provide a much more scalable design.
Distributed systems allow for direct communication between two devices (unicast), from one device to many devices (multicast), or even from one device to all devices (broadcast). This is accomplished without a master device, thereby removing a potential performance bottleneck. In addition to enhanced system performance, distributed systems are much more fault-tolerant. A specific device failure affects only one fixture or device, and not the whole system, as would be the case in centralized-control architectures.
In distributed-control architecture, intelligent sensor devices are deployed within a space to monitor changes (e.g. occupancy and daylight) and receive input, such as the push of a button from a user who wants to change the lighting. The function of these devices is to simply monitor the space and broadcast the changes they receive. These devices themselves are not in charge of implementing the control strategy; this is the responsibility of “intelligent” lighting fixtures and other control devices. These devices make the decisions on how to best respond, and do so on their own, allowing for a highly scalable and robust system.
In a distributed intelligent system, specialized nodes (gateways) can be used to allow for the connection to other systems or applications either onsite or in the cloud. This is generally done through an application programming interface (API). Throughout the API, other applications and systems can be provided with monitoring, control, and programming capabilities.
Integration with BACnet
LED lighting is set for robust data collection. It is impossible to attend a connected lighting seminar without hearing about the communication possibilities and coverage of lighting and distribution for IoT over the building environment. BACnet (data communication protocol for building automation and control networks) was created in the 1980s to establish harmony among different building environmental systems with major emphasis on the HVAC industry and its components. Fast forward to today, the BACnet committee’s efforts focus on enhancing the data exchange within the BACnet standard for networked lighting systems, thereby opening the door for serious building management system (BMS) advantages enabled by LEDs and new lighting controls technologies.
Wired, wireless, or both?
Deciding which system is best for the application can be overwhelming but there is some general guidance to keep in mind. If wiring can be easily run, a wired approach is best as it would reduce cost and provide the same functionality as a wireless system. However, if running cable between fixtures and controls would present issues such as may be found in an outdoor or warehouse application, wireless may be best. The choice is not always clear and sometimes a hybrid approach with a mix of wired and wireless systems is ideal.
In addition to issues related to cabling, consideration should also be given to the facility’s usage and potential for change. Systems requiring frequent reconfiguration or change may benefit from the additional flexibility offered by a wireless system.
There is no simple answer, so one must consider the options and select the system that best suits the desired outcome.
Power over Ethernet
Commercial building owners are increasingly enlisting the support of actionable intelligence for energy management and better building performance. Analytics (i.e. the process of turning data into actionable information) can have a significant impact on sustainability and cost-saving strategies. Power over Ethernet (PoE) solutions—scalable from basic lighting control to advanced cloud-based analytics—are in high demand because they are cost-effective for smart building deployments demanding an immediate return on investment (ROI).
The installation of PoE lighting solutions reduces material and labor costs by using a single Cat5e/6 connection for power and communication. Solutions offering modularity (i.e. the degree by which a system can be separated and recombined) offer a competitive advantage. The installation process is simplified by using a low-voltage cabling approach. The author has received feedback from facility owners who have seen tremendous advantages in having the flexibility to make infrastructure changes to support the evolving needs of real estate. Additionally, when customers go the low-voltage route, the lighting can be fixed by low-voltage installers, and it could be easily configured and reconfigured through software by IT personnel.
When evaluating PoE solutions, one must not overlook the importance of standards. Currently, industry standards are fluid and one may want to investigate and understand how the device input-output requirements are addressed by the solution.
One of the first things to do is to identify if the system is following the Institute of Electrical and Electronics Engineers (IEEE) 802.3, Standard for Ethernet. (For more, click here.) This standard allows for a “common road” to send data and links the wiring and network infrastructure. Applying this standard also ensures the PoE system is correctly connected to the corporate Internet to allow for data exchange with other systems.
