November 2008
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The Three Little (BACnet) Pigs

A Modern Day Fable of Building Systems Integration

Andy McMillan

Andy McMillan
President and CEO
Teletrol Systems Inc.

BACnet International

Contributing Editor

Once upon a time in a thriving metropolis, three little pigs were busy at their desks when they received some terrible news. Their mother, who was the dedicated and experienced facilities manager for their commercial office building, told the three little pigs they would have to move out on their own. Their mother’s office building had become too small for everyone. The three little pigs urged her to expand the building but she explained that the building’s controls had been designed around proprietary systems provided by a supplier who had recently obsoleted that product line. As she explained to them, expanding the building was easy but extending the legacy control system was just too expensive. So, they were each going to have to go out and build their own facility.

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The three little pigs looked at each other and realized that they had an opportunity to do things differently. They were determined to protect their investment by specifying control systems that could easily and cost-effectively expand and change to meet their future needs. They talked to their peers at ASHRAE meetings, reviewed product specifications with potential suppliers and read through a lot of back issues of They recognized that the best way to “future-proof” a building control system was to use standards-based solutions. When they found that BACnet is the ISO standard for building automation they all realized they needed to specify their control systems around BACnet.

The First Little Pig Finds Equipment Integration

The first little pig jumped at the chance to move quickly and get BACnet in the specifications for his building. His specifications required all HVAC and lighting equipment to have a BACnet interface. This enabled him to directly connect any supplier’s HVAC equipment to any supplier’s control components. As the VAV boxes in his building were being networked together via BACnet MS/TP he patted himself smugly on the back. He was experiencing the benefits of choosing the best HVAC equipment for his needs regardless of supplier, and no one supplier was driving the controls solutions for his building.

The little pig was very happy with his building and its well-integrated HVAC system. However, before long, the winds of change began to blow and they threatened the little pig’s complacency.

“Little Pig, Little Pig,” a sly wolf on the maintenance staff argued one day. “I’ve heard people are saving a lot of money by automatically heating and cooling only relevant sections of their building based on which people are in the building and where those people are working. Why doesn’t our system do that?”

“Well,” said the little pig, “doing that requires functional integration… that is, linking the HVAC function and the lighting function to the access control function. I only specified that HVAC, lighting and access control equipment have BACnet MS/TP interfaces to their respective controllers. I never thought about relating them to each other.” Disappointed, this little pig ran right up the road to his older and wiser brother’s building as fast as his little legs could take him.

The Second Little Pig Finds Functional Integration

The second little pig was proud to show his little brother the specifications he designed that included equipment to controller interoperability using BACnet MS/TP, but also required controllers to support BACnet/IP to simplify functional integration.

He explained to his little brother how his commercial building utilized VAV boxes and other equipment networked via BACnet MS/TP and how he experienced the benefits of choosing the best equipment for his needs regardless of supplier. As he pointed out, no one supplier was driving the controls solutions for his building, either.

So, he gained all the benefits his younger brother achieved, but with BACnet/IP, he had even more. When his maintenance guys pointed out a cost savings opportunity, the second little pig was able to achieve functional integration by using the BACnet/IP capabilities of his HVAC, lighting and access control systems. So, when a person enters the building their specific workspace is automatically lit and conditioned. The second little pig pointed out that he was experiencing the benefits of sourcing from a variety of suppliers, lower overall energy costs, and integrated building automation. He was very proud of himself.

The first little pig ran back down the road and upgraded his building controls to include BACnet/IP so he could achieve cost-effective functional integration, too. However, the winds of change began to blow harder than ever and they threatened even the second little pig’s complacency.

“Little Pig, Little Pig,” a sly wolf in the second little pig’s facilities department argued one day, “if our building system could access real time pricing and status information provided by our electricity provider, we could optimize the procurement of energy and cost-effectively participate in demand response programs.”

“Well,” said the second little pig, “doing that requires constant, reliable communications outside the traditional domain of building automation systems.” He frowned and said, “Our integrated control system can only communicate among controllers on our own network. It never occurred to me that we might need to exchange information with applications or organizations beyond our network. Enterprise integration just was not on my list of concerns.” He contacted his little brother to alert him of this alarming development and both of them ran up the road to their older and even wiser sister’s new building as fast as their little legs could take them.

[an error occurred while processing this directive] The Third Little Pig Finds Enterprise Integration

The third little pig wanted to help her brothers understand how to protect themselves from the winds of change that are driven by ever-shifting technical, regulatory and commercial requirements for building systems. She explained that the specifications she developed required that her system support BACnet MS/TP connections to equipment (like her youngest brother) and BACnet/IP among controllers to enable functional integration (like her other brother), but she also required her system to support BACnet Web Services. She said, “I knew that over time building automation would advance, and in order to take full advantage of new strategies, my systems would need to exchange information with other applications and organizations. I knew that enterprise integration using web services was going to become a necessity.”

As a result, her building achieved full interoperability among mechanical/electrical components, integrated functionality across building automation applications and her building’s control system could readily integrate with other applications over standard IT infrastructure.

Her building was practically impervious to the winds of change … which was good because before too much longer she would need to extend her system so that her building could:

And the Moral of the Story Is …

The first two little pigs had listened to their older sister and learned some valuable lessons from her experience. They ran back to their own buildings to upgrade their systems to incorporate BACnet Web Services. Of course they realized that it would have been faster and cheaper to have specified BACnet as a full system solution, all the way through to BACnet Web Services from the very beginning. So, to help other people recognize the where the industry is headed and gain the “future-proofing” benefits BACnet and web services, they created a new website at They hoped their experience would help other people understand that regardless of what specifications looked like in the past and regardless of whether or not a system has immediate application integration requirements, specifications including BACnet Web Services are the best way to protect investments in building systems against the winds of change.

As always, the views expressed in this column are mine and do not necessarily reflect the position of BACnet International, Teletrol Systems, ASHRAE or any other organization. If you want to send comments to me directly, feel free to email me at


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