Ideas to fuel a sustainable built environment

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Inigo Montoya and the Definition of Open Systems

Jan 27, 2016 10:00:00 AM

Recently there has been a lot of talk resurfacing about what defines an "open system."  It is a concept that has been debated and sold for well over a decade in the HVAC automation industry.  There still seems to be some ambiguity about what this really means.


A quote from one of my childhood heroes, Inigo Montoya from The Princess Bride, sums up my observations of the use of the term “open system.” I’ve noticed recently: “You keep using that word. I do not think it means what you think it means.” (If you’ve never read The Princess Bride by William Goldman, you should pick up a copy from your local bookstore.)

When I was first introduced to the concept of an “open system,” it was in the context of communications protocols.  I was taught by my mentors that something was open if Company X’s product could communicate with Company Y’s product on the same network.  But that’s really systems integration, and it was the fad back then.  It was supposed to free building owners from the trap of being locked in by a product, sold by a particular company. still boasts that concept.

Now some of you reading this already know that this definition is not quite accurate.  You might say, “Rick, don’t you mean ‘interoperability’ when you say ‘open system’?”  If you said that, you’re right.  Systems consisting of many different manufacturers, that are integrated and sharing data, are interoperable, not “open.” LonWorks, BACnet and Modbus are communications protocols leveraged in these so called “open systems” to create product interoperability.  But they don’t make the building automation system truly open.  

Ok, now that we’ve got that out of the way let’s discuss the current status of open building automation systems.  I will just say it: in the HVAC automation industry, there are NO OPEN SYSTEMS!  That’s right.  Nobody makes one.   Let me substantiate that claim by giving evidence from an industry that does have open systems: computer operating systems.


Right now, you can download a variety of open system operating systems.  Linux is the best example of an open system.  It is open because of the following:

  1. Linux is software in which the components and protocols are programed independent of a particular manufacturer / corporation.
  2. Linux is free and widely available!
  3. Linux’s source code is also available. It is open for review, modification, and customization.
  4. Linux has a community of developers

You could argue that the 4th bullet isn’t really criteria of what makes Linux an open system, but rather the result of it being one.  Fair enough.  Android is another great example, even though it is not independent of a particular manufacturer (Google).  You’ll note that it costs you nothing to download Android and its programming tools today.  You’ll also note that once you have Android, you can compile an app for a Samsung Galaxy device, or a LG device (manufacturer independence on the hardware – HVAC industry, take note!).  Sure, Google gets a cut of the action, but that’s only if you develop something you plan on selling.  You can still put any number of free apps out there after their onetime $25 fee.

Open systems are platforms on which you leverage your code, your solutions, and your ideas.  They’re built on standards that are regulated – ideally, but not always – by a non-profit.  Having an open system gives everyone the same tools for free, and allows their creativity to flourish out in the open where others can improve upon or remake an idea on their own terms.  The real profit comes from making something on that platform that people want.

For the HVAC automation industry to have “open” systems, they need to look at what’s out there right now in other industries where open systems have actually evolved to be truly open.  Open means open to the public.  HVAC automation manufacturers will still turn a profit like phone and computer manufacturers still do.  But do they have the guts to change their business model to match what has already happened, profitably, in other industries?

Only time will tell.

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Written by Rick Stehmeyer