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DOA in BAS?
The concept of using POE (Power Over Ethernet) as a platform for
networking in lighting and BAS control systems has a seductive
attraction. After all, it’s consistent with the current BIG IDEAs
in networking, the IoT (Internet of Things) and IoE (Internet of
Everything). And it ought to lower installation costs since it
will reduce the number of (expensive to install) line voltage wiring
points in favor of (less expensive to install) low voltage wiring
points. So, what’s not to like? Compared to the historical
approach of line voltage devices with separate network cabling POE
might be a good alternative. But is that the right
question? Perhaps a better question is how it compares to the
emerging approach of low voltage devices with wireless
networking. And in that comparison I am not sure POE will fare so
The Case for POE
I was motivated to think about this question recently when I saw an announcement that a major lighting manufacturer was releasing a new controls platform based on POE. Historically lighting has been a bit of a backwater in controls as far as commercial BAS was concerned but that is all changing now. With the introduction of LED lighting it’s becoming the norm for lighting fixtures to include sophisticated sensors and local intelligence. As a result a more robust controls networking approach for lighting is essential. At the same time, the adoption of LED light sources enables a low voltage approach to powering lighting devices. So it seems natural to combine the two by adopting POE for lighting controls.
And it is not just lighting. I was talking to a very experienced valve manufacturer recently and they were looking at POE, too. In fact, they had a prototype device and were working out the bugs. Their motivation is largely the hope of reducing implementation costs by reducing line voltage wiring points in system installations.
In both domains POE seems like a safe strategy, especially for companies with limited presence in the controls industry and little networking expertise. After all, POE infrastructure and protocols are fully developed and easy to deploy. POE has seen wide use in the corporate IT space so Cisco and others provide off-the-shelf components and tools. Development costs are minimized and the ability to rapidly scale seems assured. So major suppliers without substantive network technology development experience could do worse then turn to POE for their controls networking platform. But is this “safe strategy” good enough to position them for success as the controls industry is disrupted and reformed in the coming years (elsewhere referred to as Automation Armageddon)?
Of course one challenge to POE in BAS is the use of low power wireless networking combined with low voltage power distribution. Tremendous innovation in this arena over the last five years has created a number of approaches that are, each in their own way, compelling. One of the threats to POE in BAS from the networking side is lighting controls based on wireless mesh network technology. Leaving aside the techno-religious discussion about which low-level protocol is the “right” one, the fundamental capabilities of wireless mesh networks are very attractive, especially when used in conjunction with lighting. And, as I have pointed out in previous columns, lighting is likely to become the foundation of BAS controls implementations in the future so this could drive wireless throughout BAS … in spite of any POE push by traditional controls suppliers.
A second (and perhaps greater) threat to POE success in BAS is the emergence of “zero wiring” physical infrastructure. One example is the Emerge Alliance group that has been working for some time to develop and deploy DC power microgrids in building. One of the standards they have developed is a ceiling grid for commercial buildings that embeds DC power as part of the mechanical grid. So individual lighting devices (and HVAC and other devices) can be placed anywhere in the ceiling grid and pick up low voltage power. If those devices also use wireless networking then installation wiring points drop to near zero … which is much better than POE.
A second path to “zero wiring,” is energy harvesting. The enOcean Alliance, for example, has motivated the development of hundreds of sensors and switches that communicate wirelessly using tiny bits of energy extracted from their local environment. Technologies like this, especially coupled with continuous improvement in long-term battery technology, makes it reasonable to expect a substantial portion of BAS infrastructure to become self-powered and totally wireless … which is quite a bit better than POE’s best case.
In The End …
Readers of my May column in this publication know that I believe companies need to move quickly to keep up with the accelerating change in the BAS industry. Nowhere is this more important than in networking. Adopting POE as a proven technology from IT and applying it to lighting and BAS controls has some merit but it does not feel much like moving quickly. As a result, whether it turns out to be DOA (Dead on Arrival) or a winning strategy is not so clear. Personally, I think I would place my bets elsewhere … but then, that’s why it’s called a bet.
As always, the views expressed in this column are mine and do not
necessarily reflect the position of BACnet International, ASHRAE, or
any other organization. If you want to send comments to me
directly, feel free to email me at email@example.com.
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