Using PoE networks to power smart infrastructure for commercial buildings

Author : Giovanni Frezza, Group Product Manager for Network Connected Solutions at Molex

04 April 2018

This piece from Molex reviews PoE technology and standards, outlining how it can power smart lighting and building automation systems – and the benefits these can deliver for building operators and occupants.

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Communications networks using Power over Ethernet (PoE) technology can transmit electrical power, as well as communications signals, over standard low-voltage Ethernet cabling to various endpoints (including LED lighting, HVAC controls, cameras and other networked devices) in new or existing commercial buildings. 

Power over Ethernet lighting and building automation systems, designed to promote energy efficiency and boost productivity, are beginning to drive highly innovative smart building concepts. As operational technology (OT) rapidly adopts PoE infrastructure in commercial buildings (including offices, factories and warehouses), architects, developers, builders and engineering firms become crucial collaborators – alongside information technology (IT), who have traditionally owned the infrastructure PoE utilises.

Together, these proponents are leading the charge to bring powerful PoE networks into commercial spaces, with significant new build, retrofit and pilot installations underway – and many more in the works.

Forward-thinking adopters have recognised PoE infrastructure as a key asset for enabling IoT and smart building initiatives: one that can add significant value for building developers, operators and occupants. Advanced technologies are driving network-connected lighting use cases and more efficient standards in building automation. Unlike traditional networks that require dual-layer infrastructure (via separate power and communications networks), PoE platforms enable power and data to share the same low-voltage Ethernet cable infrastructure.

Although many installed control systems today are based on proprietary solutions, leading technology suppliers and the commercial building industry are trending towards the use of open standards to simplify the commissioning, design, installation, configuration and maintenance of new networks.

The technologies used in PoE networks are well defined by various IEEE 802.3 standards, which specify the physical and data link layers for wired Ethernet networks power sourcing equipment, and devices using two-pair or four-pair connections to transmit power.

The original PoE standard (IEEE 802.3af-2003), based on 15.4W per switch port of power, was increased to 25.5W in PoE+ (IEEE 802.3at-2009), using a two-pair power transfer format.

The upcoming IEEE 802.3bt standard will utilise a four-pair power transfer format (4PPoE: 4 Pair Power over Ethernet), designed to introduce and support two additional power types: up to 60W (Type 3 or UPoE: Universal Power over Ethernet); and up to 90–100W (Type 4 or PoH: Power over HDBaseT) per switch port.

Utilising all four twisted pairs, UPoE technology can deliver more power than PoE+, with improved efficiency and reduced channel losses. This allows the option to optimise the low-voltage cable infrastructure by daisy-chaining multiple devices on a single UPoE port, thereby reducing the number of ports and amount of cabling required in a system. The new IEEE standards also improve efficiency and allow a wider range of device functions and support – and can be delivered on standard low-voltage Class D (Cat5e) cables (using the same infrastructure that the IT industry has deployed for over a decade).

A distributed network allows building or enterprise-wide precision control, integration with other building automation systems, and better data to inform workforce and building usage decisions. Standards and specifications establish protocols for both power delivery and communications links for data exchange.

However, this doesn’t tell the entire story about the value PoE networks can bring to building control systems. The proliferation of smart technologies is setting the stage, with architects, electricians and installers on the frontline using PoE LED fixtures to transform buildings.

Legacy lighting fixtures can be readily retrofitted with LEDs and sensors capable of local smart control. These lighting systems in older buildings have utilised AC power that has been converted to low-voltage power. Retrofitting existing lighting fixtures with LEDs was the first step for many building operators. Penetration in commercial building markets has made LEDs surprisingly cost-competitive versus other lighting technologies. Outstanding lighting output per watt of power has been the primary driver of initial LED adoption in commercial buildings, greatly improving on traditional lighting technologies.

Advanced LED technologies are becoming increasingly versatile, efficient, secure and capable of supporting available wattages in PoE lighting systems. Meanwhile, the ability to migrate lighting controls to IP-based infrastructure is transforming lighting into a service and IoT building asset: one that can be controlled synergistically along with other building functions. Increased integration is driving not only better control – leading to dramatic energy savings, increased occupant comfort and improved productivity – but also more meaningful and usable data collection by distributed sensor systems, as part of the lighting network infrastructure.

Optimised to deliver low-voltage power and reliable communications, PoE gateways distribute power and connect luminaires, sensor nodes, wall dimmers, and other local devices and controls to the IP network and control manager. Each gateway is connected to a switch port with a Cat5e cable.

The IP nodes are responsible for power and data distribution to local devices. Lights, sensors, motorised blinds and other devices become digital objects that can be configured, grouped together and controlled via software. Good cable design is important to optimise the low-voltage power distribution for efficient and cost-effective implementation.

Well-implemented PoE control systems also deliver high availability of uninterrupted power service, greater network resiliency and reduced operating expenses. New networks and devices become faster to deploy since PoE networks do not require power outlets at each device endpoint.

Commercial buildings are prime candidates for PoE lighting and automation systems, which can either be designed in as part of a building’s infrastructure, or retrofitted into existing infrastructure. Ideally, designs need to optimise power and data distribution to minimise the number of PoE ports required.

For instance, if the power requirement for a group of devices is below 50W, a single PoE gateway can power and control multiple drivers in a daisy-chain configuration. System software tools can provide support during the complete lifecycle of a networked control system, from design and installation to live operation, monitoring and building maintenance.

PoE networks deliver a range of advantages for building operators, starting with the supply of both power and data over a single-layer infrastructure, using proven, scalable and future-proof standard Ethernet cabling. The DC power supplied is ideal for LED and sensor applications, using low-voltage and safe-to-install standard RJ-45 connectors (without the need for a certified electrician).

PoE networks also enable advanced control of highly tunable LED luminaries and dynamic/bio-adaptive controls, creating new paradigms and value in commercial building connectivity and data analytics. Easy convergence and integration with existing building automation systems and infrastructure allow digital zoning or re-zoning, increasing flexibility to optimise building zones for specific use cases, with easy repurposing to meet future needs. Granular sensor arrays allow superior automation and data reporting, as well as simple implementation of new use cases to increase productivity and operational efficiency.

PoE technology takes LED lighting in commercial spaces to the next level, further reducing energy consumption and improving quality of light – with smoother intensity and dimming functions, and dynamically adjustable colour output to create more comfortable and productive work environments. Building operators have ready access to light status, real-time energy consumption data, sensor-based occupancy reporting, air quality, temperature and other environmental monitoring.

This aggregate data translates into tangible business insights, in terms of flow patterns and space utilisation, conditions within those spaces, as well as how different spaces, floors, or buildings rank or compare when it comes to occupancy, utilisation, energy usage and productivity.

The elimination of a dual-layer infrastructure to distribute power and communication, data and control makes new construction simpler and faster than traditional hardwired AC/DC distributed lighting and automation systems. Powered via low-voltage Ethernet cables and standard RJ-45 connectors, each LED light or element in the building also receives an IP address.

Changes in space utilisation benefit from reduced installation time and cost, by eliminating much rework of wiring. A network-connected system allows rapid changes in device parameter settings and zone programming, simply by re-assigning sensors depending on space utilisation needs.


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