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« Commercial Use of Live Energy Models | Slim BIM: The Middle Ground between Document and Service Part 1 »
Wednesday
May302012

Slim BIM: The Middle Ground between Document and Service Part 2

In my last post, introduced Slim BIM and the critical need for shared configuration to speed development in the building systems. This post extends that conversation.

A report from NREL, delivered last Spring, defined the Building Service Interface (BSI), a standard for interacting with building systems from non-building applications. That report recommended that each BSI be able to share a light-weight BIM, i.e., to be able to provide on demand a description of the space it supports, the systems it controls, and the relationship between systems and space. In the future, this light-weight BIM is likely to be part of minimum commissioning standards to get LEED or other environmental certification.

Mary Ann Piette, Staff scientist at Lawrence Berkeley Labs and Director of the Demand Response Research Center, has called these light-weight models “Slim BIM”. Today, there are two well-known specifications for Slim BIM: COBIE and GBXML.

Green Building XML (GBXML) is already well known to the building automation community. GBXML was originally developed to prepare energy models. GBXML has an easily used schema that is maintained by the non-profit Open Green Building XML Schema (gbxml.org). GBXML has become the de facto standard for exchanging information between with engineering analysis tools. GBXML is typically produced by CAD software including applications from Autodesk, Bentley, and Graphisoft. GBXML is used by energy modelers, HVAC design tools, ductwork CAM tools, and many others. GBXML is so well accepted, in part, because its schema is specified using modern tools that are easy for software developers to use.

COBIE, the other Slim BIM, has found a harder path to wide acceptance. Much of the COBIE produced today is of poor quality and semantically incomplete. Within BIM, information is exchanged using the Standard for the Exchange of Product model data (STEP). STEP is able to convey almost any kind of information, including detailed 3 dimensional data. The problem is, most users of this information do now want complete specification and wide extensibility; they need terse, validate-able information exchanges. Most users do not want detailed purpose-built information exchanges developed slowly in committee; they need ready-to-use exchanges that suit a variety of purposes. COBIE’s slow uptake epitomizes the cultural and technical differences between the engineered world and commercial IT.

COBIE would face less cultural resistance if it looked more like other inter-domain information exchanges. Some proponents have claimed that there is a COBIE XML format already. COBIE was initially described as “a spreadsheet of the data you need to operate the building”. Accordingly, standard Excel templates for COBIE are available. Today, the XML representation of COBIE is the XML representation of a Microsoft Office document. As this format is not very useful, most COBIE is produced as hard to understand, hard to verify CSV files or STEP text. The only COBIE verification tool that I know is offered by Onuma Planning Systems (http://www.onuma.com/products/OpsAndCobieValidate.php).

The Army’s Construction Engineering Research Lab (CERL) is a pioneer in using construction information to improve building design, acquisition, and operations. To CERL, improved operations are central to sustaining facilities not only during lean budgets, but also to sustain mission support. CERL’s PROJNET system, used by thousands of organizations, is the leading producer and user of COBIE. PROJNET maintains an internal XML representation of COBIE, one that is not now part of the specification.

When CERL releases its XML representation of COBIE, I predict it will soon become the dominant form for information exchange. A version of COBIE that is as easy to use, and as clear to understand as the GBXML schema will find rapid acceptance throughout operations. CAD vendors that produce poor or incomplete COBIE today will up their game. Current CAD systems require requires a few simple early design decisions to be able to produce good COBIE; designers who skip that step will find themselves at a competitive disadvantage.

Even the mash-up approaches to BIM will benefit. A CMMS that can export well-formed COBIE will be able to export information to Cloud-based BIM. Mash-ups between 3D building models and energy management systems will become common and expected. Well-formed, validate-able COBIE will make building information more visible than it has ever been, visible to the right user, at the right time, with the tools of that user’s choosing.

As these approaches replace the one-time, hard to perform integrations of today, BIM and system integration will become rapid and easy. Cloud-based techniques will reduce the costs of technology changes within each building at the same time as they expand the owner’s awareness of these changes. Shareable configuration is the path to rapid secure service integration.

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