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Tagging – What’s That Got to Do With My Building?

Tagging is a way to create a relationship between a number of items in software without having to change or understand the underlying information (code or schema) about those items.

Kevin Binnie
Kevin Binnie

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What is Tagging?

What is Tagging?Tagging is a way to create a relationship between a number of items in software without having to change or understand the underlying information (code or schema) about those items. In the physical world, we are familiar with tags. Perhaps the most obvious example is at birthdays or during the holiday season when gifts are tagged: I can tag a gift with information about who the gift is for and who it is from and even the occasion that the gift is intended to celebrate without knowing anything about the gift itself.

In everyday life, tagging technology has helped make our lives more convenient: barcodes or Universal Product Codes (UPCs) are a form of tag that tells the scanning system at a grocery store that the item scanned is a box of cereal with a particular price. This eliminates human error in identifying the price of that box of cereal, including if the cereal happens to be on sale. Another everyday use of tagging is the popular hashtag in social media, identifying a popular subject. In the recent US election, hashtags like #election2016, #HRC (Hilary Rodham Clinton) and #trump2016 gave voters an easy way to read about goings on during the election. We can also scan QR Codes with our smartphones to take us quickly to popular websites or download coupons.

In the picture, you can see that the gift is to Alex from his mother and that it is for Christmas. It also has one more important piece of information: timing, as in “Do not open until Christmas.” In the world of Building Automation Systems (BAS), tags can be used to help unravel the complexities of the building equipment, including the relationships between various pieces of equipment. For example, I can tag a particular piece of equipment “Boiler” and I can tag another piece of equipment “Boiler fed reheat.” In practice, I would likely work to create tags that are simple, easy to follow and readily convey the specific information that I need. I can even tag abstract concepts such as “schedule” or “temperature.”

In BAS, controls engineers have been effectively tagging trend logs for years in the way that they name the trend log. It’s not uncommon for a trend log to be named something like “AHU_1_VAV_2_SAT,” which contains a significant amount of information: just by looking at the trend log name, I can guess that it is the Supply Air Temperature entering Air Handler 1’s VAV number 2. That’s quite helpful for someone who is looking at the trend log and trying to understand what it is.

There are, however, several challenges to this method. Firstly, not all trend logs are named in a way that is this easily understood. Secondly, since typically trends are named by hand one at a time, they are prone to typographical errors, which can change the context significantly. Thirdly, since it’s permissible in the BACnet standard to name the trend log anything, this same trend log could just as easily be named “VAVST,” which is a lot less clear or helpful. Finally, and perhaps most importantly for owners and operators of multiple buildings, if the buildings were set up by different operators – or worse, use different controls – the naming convention will almost certainly be different, which means I can’t automate the categorization of the trend logs for review or analysis.

Haystack Tagging

It’s clear that the use of some form of tagging helps to get around many of the challenges presented by trend log naming. But what is the best tagging model and why is it important? Project Haystack is an organization founded by a group of concerned companies to set out a framework for the BAS industry. Project Haystack defines both a structure and a set of tags that are commonly used in BAS. There are 217 pre-defined Haystack tags, and they offer a tremendous advantage over named trend logs: they are standardized across all vendors that adopt the standard, so there is much more clarity of information on standard equipment types between buildings, they help create a common nomenclature between applications, so set up time for applications such as Building Management Systems and analytics programs are significantly reduced, but most importantly, they can be set in equipment and controllers at the manufacturer, virtually eliminating the need for onsite naming by contractors. This last point also means that the likelihood of getting it right the first time is significantly increased.

So how does Haystack work? Haystack provides a framework for the industry to share relational (meta) information on common devices in a building. It is comprised of a series of definitions for the TagModel or tagging framework, the Structure, which defines the key entities, Time Zones, Units, Grids to support the representation of tagged devices in a table (like  in Excel) and Filters. There are a lot more elements to Haystack which coders will find important, but they are not critical to understanding Haystack.

The TagModel is simply the definition of how tags are structured for interoperability when sharing data between applications and/or devices, such as between a controller and the BAS. First are entities, which is the virtual (computer) definition of a real-world piece of equipment, like a piece of equipment, a sensor point or even a site. Next is the definition of tags, which in the Haystack world, are name/value pairs that are associated with a particular entity. I could, for example, tag an entity with vav, which indicates that the entity is a VAV. I could further tag it with coolOnly, which further defines the VAV to be a cool-only VAV with no fan power. Or, as in the diagram, I could tag the VAV’s fan with the tag fan. I could further add the tag damper to indicate the damper position.

Free-Form Tags

Haystack provides a great many advantages in a BAS, but free-form tags are perhaps even more useful. While they require more manual effort than the convenience Haystack tags offer, since individual tags have to be created and applied manually, their flexibility makes them useful across a much broader range of uses than the limited Haystack set. A free-form tag is one that is defined by the user and is generally a word or series of words that have some context for the user. They are also generally shareable and able to be combined to act as a form of filtering to get to specific information of interest.

Tagging tools are available for tagging everything from pictures and music to blogs and websites. The popular Customer Relationship Management software service SalesForce supports tagging of knowledge based articles to allow Customer support personnel to find articles on a subject matter of interest quickly. These articles and tags can even be exposed on a website that allows customers to ‘self-serve’ help articles.

Tagged VAV

In the building context, free-form tags would allow users to track information on the system (VAV, AHU), building or even the portfolio level. For example, if I had a portfolio of buildings across North America, and those buildings were a combination of different building types, such as retail, commercial and mixed residential, I could free-form tag those buildings by type, location, size and more. I could tag buildings as being South, West, or South and West.  I could then quickly filter down to all commercial buildings of 100,000 square feet or less in the southwest. Combining with Haystack tags, I could further filter down from that set of buildings to all buildings with boilers, and more specifically those boilers with gas meters to compare their relative energy efficiency.

It won’t be long before these tools are adapted or incorporated for use in BAS and BMS solutions; some already support tagging in one way or another. It will, of course, take time for the full benefits of Haystack tagging to be realized as more and more vendors adopt the standard and incorporate tags in their equipment right from the factory, but in the meantime, free-form tagging offers a path to making buildings and their equipment more accessible.

About the Author

Kevin Binnie is currently a free agent with over 20 years of experience in product management, marketing, mergers & acquisitions, and new market development to develop and deliver software services that help companies to realize their building’s potential while reducing their environmental impact and creating better spaces for people to live, work and play.


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