The Bright Future of Power Over Ethernet-Driven LEDs

by | Jan 22, 2016

Dyson LEDThe marriage between telecommunications and energy management is rife with potential. And, for that reason, the marriage promises to be a long and happy one. To date, most of the discussion has been focused on the use of the Internet of Things (IoT) to manage energy consumption.

A related – and arguably deeper – relationship between the two is emerging. Buildings in general and office buildings in particularly house miles and miles of cables that support the local-area networks (LANs) that link PCs, printers, WiFi access points (APs) and other pieces of technology. The copper and coaxial cables that are the physical media for LANs are capable of carrying small amounts of electricity. Thus, some of the less demanding equipment – such as phones and APs — can be line powered.

But why stop at APs and phones? LEDs take less power than legacy lighting and, thus, can be supported by power over Ethernet (PoE) This week, Royal Philips said that it is using the approach to power LEDs at Clemson University’s Family Innovation Center.

The savings can be significant. “Typically Lighting consumes 40% of a building’s electricity,” Jeff Cassis, Philips’ Business Leader for Professional Systems, told Energy Manager Today. “Philips connected LED lighting offers up to 80% energy savings on the lighting. This equals a reduction of 30% on the buildings total electricity consumption.”

The Philips project and work by other vendors has a long background. The idea of sending power over communications networks is almost as old as the telephone network: Legacy telephones operate during power failures because they are line powered.

A year ago, Smart Buildings Managing Partner Jim Sinopoli laid out the modern history of PoE in an Energy Manager Today post. The starting point, he wrote, was at the turn of the century. Entrepreneurs wanted to use the Internet for phone service (VoIP) and sought a way to power customer premise gear without plugging it into an outlet. PoE was born.

It has grown quickly. As of a year ago, Sinopoli wrote, more than 100 million PoE-enabled ports were shipping annually. There are standards and multiple suppliers. Though LEDs are not mentioned in the post, the jump from powering and controlling an AP to powering an LED is a small one.

The Clemson project is a high profile next step. “Instead of a facility manager having to deal with a separate control system for intelligent lighting, Philips’ new connected lighting system for offices becomes one aspect of an integrated system that includes other important site services, such as HVAC services,” Cassis wrote.

The ability to control lighting and expenditures becomes increasingly granular in such a landscape, especially when the Internet of Things (IoT) generates data that can be leveraged into a variety of value-added advantages. “Together, Philips’ intelligent fixtures and sophisticated system management software enables building owners to receive comprehensive real-time and historical views of a building’s usage and activity, allowing them to optimize energy efficiency while giving office workers a high degree of comfort and control over their environment,” Cassis wrote.

Philips is not the only company that sees the value of PoE-driven LEDs. Maxim Integrated’s Alec Makdessian writes, in a white paper at the company’s site, that expenses are lowered because cabling costs are halved and installation no longer requires a licensed electrician. An added bonus is, like those old phones, the lights have a better chance of staying up during grid failures.

Mike Hornung, IHS’ Market Analyst for LED and Lighting, told Energy Manager Today that this approach only can support smaller LEDs due to the thinness of the Ethernet cable. There are different approaches, he wrote. “On a technical level, there are currently a few ways of doing this, but the two most common are using part of the cable for power and part for connectivity, or applying a voltage offset to the signal. Cat-5 Ethernet cabling contains 4 ‘twisted pairs’ in each cable, and for low speeds only two of these pairs are used. Therefore the other two can be used for supplying power. Ethernet uses ‘differential signalling’, where the voltage on the line switches to a positive to negative voltage (e.g. 5V to -5V) to represent the ones and zeros of a digital signal. But if you shift the voltages (to 10V and 0V) you might have a positive average voltage on the line, which can be extracted from the other end.”

The idea of deeply integrating lighting, the IoT and PoE is exciting to planners. For example, amBX CEO John Niebel suggests in a commentary at Modern Building that the benefits may start with savings on existing technology but evolve to offer tools to fundamentally transform work spaces:

The energy-saving performance of LED lighting has been well documented, but this control technology offers benefits beyond merely saving money and delivering green lighting. This software will also enable building owners to use richer, bio-adaptive lighting in new ways to create healthier, more productive workspaces and environments. This will lead to better human-centric lighting at desks, in meeting rooms and public spaces, in terms of intensity and colour changes.

Clearly, PoE-powered LEDs have a tremendous amount of potential in both the short and long term.

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