BSI Part 3: The Metadata Problem
Tuesday, January 25, 2011 at 05:00AM
Toby Considine in BIM, Enterprise Interaction, Intelligent Buildings, Standards, Synergies

After the ASHRAE meetings, and during the AHR conference, several of us are getting together to discuss building system metadata. The goal is to define interfaces to support quick fast integrations of building systems into the wider world. This is the third of several posts describing this interface. Drop me a line or watch for announcements from LONmark if you want to join us for discussion.

Metadata refers to information about data. While control systems for buildings can offer up an impressive amount of data, it takes far too much effort to figure out what it means. In a medium-sized commercial building, tens of thousands of points can take a month to unravel before useful integration with the businesses and lives of the people who occupy those buildings is possible. Throughout all the integrator must understand the technologies in use in that building. At the end, the integrator produces proprietary results himself.

Most of that integration effort is in deciphering what those information points mean. Is that point an internal point, useful only to the HVAC professional, or does it represent a room temperature, or oxygen level, of interest to the building occupants. Do these points describe one air handler or ten? Are all air handlers fed by the same compressor? What space, which means what business services, does each system support? The answers to these questions can be discerned by the trained professional, with the blueprints in one hand, and years of experience in the other. Today, they cannot be reliably determined by machine inspection.

We need a relatively few profiles to pull this off. Or maybe we just need some rules about profiles, and a place to create a repository. Too many profiles could just recreate the chaos we have now, in which metadata is all free-form tags.

There are several existing profiles for communicating with energy meters; we need to get to one. The profile model should be able to indicate what systems are behind it, by reference, to the discoverable catalogue of building systems and spaces. Whether you call it live load, or plug load, circuits and the space they support can be described in PLIie. Everything, of course, should be tied down to the space or spaces it supports.

BIM standards contain standard descriptions for how a space is used. The links to space, offer potential keys into business directories and business schedules.

The place to start collecting this metadata is during commissioning. COBie (Common Operations Building information exchange) defines a family of information models that can be handed over from a construction Building Information Model (BIM). These include a catalogue of building systems and the spaces they support. As retro-commissioning starts to follow commissioning standards, we would begin to get the benefits of the BSI-enabling metadata in existing buildings.

Article originally appeared on New Daedalus (http://www.newdaedalus.com/).
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