LpR Article | Jun 06, 2016

Power over Ethernet Lighting for Commercial Buildings by Molex

Today, information technology (IT) and lighting are separate worlds. It is necessary to create a bridge between these worlds, not only from a technical standpoint but also from the perspective of understanding what is important to each industry. Giovanni Frezza, Group Product Manager at Molex, discusses how LEDs and PoE may pave the way with new power standards: LEDs far outperform the lumens output of older lighting technologies. Today, the PoE standard for LED is 30 W. An UPOE standard for 60 W is in the works, and an expansion called BP is in progress for up to 95 W.

Power over Ethernet (PoE) lighting is beginning to transform the lighting industry and the industries it serves. While the concept is being used in commercial buildings, it is poised to break out in 2016 as large-scale projects get underway. Growing affordability and higher efficiencies are driving the use of PoE lighting in commercial buildings, making possible concepts such as the smart building and other applications that drive efficiency and productivity. Innovative owners of enterprises and buildings are beginning to perceive PoE lighting infrastructure as an asset that enables practical applications for the Internet of Things (IoT) and smart buildings while adding significant value to buildings and companies.

While still in an early stage, LED penetration in commercial buildings is reaching critical mass, making it cost competitive with other lighting technologies and enabling deeper market penetration. This represents one of the key elements driving the introduction of PoE lighting. New commercial buildings are the best candidates for PoE lighting systems, which can be designed as part of a building’s infrastructure but deep retrofit projects are appropriate as well. There have been significant pilot installations of PoE lighting in commercial buildings but, as mentioned above, several larger scale installations are being developed.

New Control Methods
The adoption of LED fixtures in commercial buildings is accelerating interest in PoE lighting because more efficient and higher performance control makes it more affordable in commercial buildings. To date, the lighting industry has focused mostly on retrofitting existing lighting fixtures with LEDs to replace older technologies, such as fluorescent and compact fluorescent lighting. Controlled LED, however, not only improves efficiency but also provides better light quality, smoother intensity/ dimming control, and dynamically adjustable color temperature, providing the right light when and where it is needed. This results in augmented worker comfort and more interactive and purposeful lighting and spaces for people. The ability to migrate lighting control to network IP-based infrastructure makes lighting a service and an IoT building asset that can be controlled synergistically along with other building functions.

Figure 1: A schematic of the Transcend® Network Connected Lighting, a PoE lighting system. Transcend comprises software, networking technology, category cables, sensors, a PoE gateway, and can be used for lighting fixtures from various manufacturers

It is important to note the difference between smart lighting and PoE lighting. Smart lighting does not necessarily need to be connected to a central network, and can be implemented simply by retrofitting older lighting fixtures with individual LEDs and sensors capable of simple, local control. PoE lighting, on the other hand, requires a centralized, software-based control system that coordinates all the elements in the lighting system, including luminaries, sensors, actuators and other devices. Lighting infrastructure is always present in a building and it’s very granular. More integration means not only better control but also more data and information being collected by a distributed sensor system as part of the lighting network.

These data have the potential to open up a new value proposition for commercial buildings. The first application is, of course, real-time energy usage reporting, but other applications - such as sensor-based occupancy reporting, light status and environmental monitoring - provide an entirely new view into how commercial buildings are used. By analyzing this data, it is known how many people are in the building at given times, where they are located, how spaces are being utilized, the condition of those spaces and how usage of different areas of multi-floor and multi-building campuses compare to each other. All told, PoE lighting will dramatically accelerate the integration of the IoT into commercial buildings.

Key Obstacles
While progress is being made in the deployment of PoE lighting systems, several obstacles to deeper market penetration must be resolved.

Today, traditional connected lighting systems are difficult to design and commission. The installation, configuration and commissioning process must be simpLi-Fied and standardized, which will boost adoption significantly.

Also, PoE lighting systems need to be easily understood by lighting architects, building owners, facility managers, installers and users to truly unlock the value associated with these systems. The lighting infrastructure and its installation cannot be disruptive to the management of the building. In addition, the software used to control PoE lighting systems must be very simple and user friendly.

To date, the majority of installed PoE lighting systems are based on proprietary systems, but the industry needs open standards and interoperable systems that can simplify integration with the rest of the building automation network.

New Power Paradigm
PoE is one of the most promising technologies allowing IP convergence for building automation networks (BANs) - including lighting - without the use of proprietary systems. LED technology requires low-voltage DC power in a different manner than older lighting sources, which utilize AC power that has been converted to low-voltage power. A smart PoE lighting system requires low-voltage power distribution and data communication for control. Distribution of power and data on low-voltage cabling is possible using the same infrastructure that the IT industry has deployed for 15 years, allowing growing penetration of LED lighting in indoor areas for various applications, such as data centers, office spaces, educational institutions, healthcare, and hospitality.

PoE delivers electrical power over category cabling to networked devices and is widely deployed to provide power to various endpoints in commercial buildings, including VOIP, cameras, HVAC and now lighting. PoE offers high availability for power, guarantees uninterrupted service and lowers operating expenses by providing network resiliency at a lower cost by consolidating backup power. It also offers faster deployment of new networks by eliminating the need for a power outlet at every endpoint.


Figure 2: Technology integrated within PoE lighting systems allows for full customization. End users can adjust lighting needs based on defined zones

PoE Requirements
PoE is a well-defined technology through IEEE802.3, which specifies the physical and data link layer media access control (MAC) for wired Ethernet networks. A PoE network includes PSEs (power sourcing equipment) and PDs (powered devices), with the PSE using two-pair or four-pair connections to transmit power. The PD negotiates with the PSE, according to a specification, to establish the appropriate communication protocol between the devices to deliver power and create a link to exchange data.


Figure 3: PoE lighting system modules (top right) allow lighting designers to implement a variety of lighting methods, including directed, indirect, ambient, and decorative

The driver of LED efficiency is its outstanding lighting output per watt of power, which far outstrips that of older lighting technologies. While already advanced, LED technology is becoming more versatile, efficient, secure and capable of supporting available wattages in PoE lighting systems according to the IEEE 802.3xx standard. This standard has been proven as a mechanism for classifying the endpoint devices needed to establish power connections.

For example, the original PoE standard IEEE802.3af, based on 15.4w per switch port of power, has increased to 30 W in PoE+ (IEEE802.3at), today’s standard. However, a new de facto-standard has been developed called UPOE, which delivers 60 W per switch port. The standard is due to change again soon with the recently introduced Power over HDBaseT (POH) standard, which supports over 95 W per port. The IEEE is working to standardize the 60 W and 95 W PoE options under the 802.3bt specification, which should be completed in 2017. The technology is backward compatible and interoperable with the existing IEEE standard.

The 60 W and 95 W standards are based on using a four-pair power transfer format rather than the two-pair format used by the 30 W PoE+ standard. The new standards improve efficiency and allow a much wider range of device support while using the same low-voltage Class D (Cat5e) cable as the PoE+ standard.

In the existing PoE+ standard, a two-pair 30 W system delivers electrical power over two of the four available twisted pairs in Cat5e cabling. In this system, the pairs 1, 2 and 3, 6 are used to transport power from the PSE to the PD and the spare pairs (4, 5 and 7, 8) are idle. The 60 W UPOE standard uses the same cabling as the 30 W PoE+ standard, but while the two-pair system uses one PSE controller to power the PD through the signal pairs of the cable, a four-pair system uses two PSE controllers to power both the signal pairs and the spare pairs.

Because it uses all four twisted pairs to deliver power, UPOE can deliver more power and is more efficient than PoE+, reducing channel losses. More specifically, a UPOE PD node can receive up to 51 W of power, enough to support lighting requirements in a wide variety of indoor applications. It also offers the possibility to optimize the low-voltage cable infrastructure by daisy-chaining multiple devices on a single UPOE port, reducing the number of ports and amount of cabling required on a system.

Cabling Architecture
In the IEEE PoE standard, the maximum allowable cabling length is 100 m (total) between the PSE and the PD, which allows the development of a single lighting system for about 15,000 square feet of space. Strategies for optimizing the low-voltage cable infrastructure required for PoE lighting have led to several system architecture innovations, allowing lighting architects to re-think interior commercial spaces and how to redesign IT closets to support BANs and traditional IT applications.

PoE lighting networks also require new expertise in the design of cabling architecture and infrastructure in order to support efficient PoE lighting deployment. Companies that develop and possess this know-how will be the ones with the capacity to efficiently scale the technology. The challenge will be to develop efficient, deployable, reliable and commercially successful PoE lighting systems on a large scale, but the tools are already available to do that. Moving forward, large-scale deployments will become more common.

The key will be optimizing the low-voltage cable infrastructure to deploy power and data in a more convenient way. This will require a hybrid deployment of technologies, including PoE and distributed power conversion. Another issue will be limiting power losses over the low-voltage cable infrastructure. Molex is implementing a PoE lighting architecture that reduces power loss to below 5% on category cables.

Power losses can also be reduced by using heavier gauge cable. While CAT 5e, 24-gauge cable is the minimum that can be specified for a PoE lighting system, as a best practice we recommend CAT 6, 23-gauge. We design PoE lighting systems that minimize the bundle size for cables (usually fewer than 48 cables per bundle). In general, the recommended maximum bundle size is no more than 98 cables to keep heat within an acceptable range; if temperatures exceed pre-specified limits, power must be reduced.

Advantages of PoE
PoE lighting is practically the only effective technology that allows power and data on the same low-voltage cable infrastructure; any other connected lighting system requires a dual layer infrastructure: one to distribute power (i.e., AC main) and another to provide communication, data and control on low-voltage cables or wirelessly.

In new construction, the installation of PoE lighting fixtures is much simpler and faster than the installation of a traditional hard-wired AC/DC distributed lighting system. PoE lighting elements do not require the use of an electrician and are powered/connected with an RJ45 connector. Because low-voltage cabling is installed as part of an IT system, no additional costs for control are required for a PoE system, and commissioning is very simple because each lamp receives an IP address.

Also, if you need to change a control scheme or rearrange a configuration in a traditional lighting system, the wiring scheme must be completely reworked, which is a time-consuming and expensive process. PoE lighting, however, is totally configurable. If you are reconfiguring office spaces, for example creating rooms from open space or vice versa, you can change zoning and control in a PoE lighting system by simply re-assigning sensors; no re-wiring is required.

The advantages of PoE lighting can by summarized as follows:

  • Power and data over single-layer infrastructure
  • Uses DC power - ideal for LEDs
  • Is low-voltage and safe to install; no certified electrician required
  • Uses ethernet standards
  • Is future proof and upgradable; each light and sensor has an IP address that can be re-configured at any time
  • Software and firmware upgrades can be made from the network without the need to change hardware
  • Advanced control is possible: a PoE lighting system can include tunable luminaries and incorporate dynamic/bio-adaptive control. Lights can be used to communicate information to users
  • Can be integrated with other systems
  • Highly secure
  • Creates the possibility for new data analytic schemes

New Lighting Paradigm
Through the development of new products and new, more efficient standards, PoE lighting is rapidly becoming a key part of commercial building design, and companies that create enabling technology for this new technology will help drive the industry through the transition.

Also, keep in mind that, as with any new technology, potential new benefits of PoE lighting will likely emerge. As commercial buildings migrate to the IoT via IP protocol, that opens the door to big data analytics, and the long-term significance of that development as part of the value proposition for PoE lighting is just becoming understandable.

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