Wednesday, August 3, 2011

Classification Systems for Building Products and Materials

In this day of BIM based design, the concept of cataloging materials has been turned on its ear. It’s no longer enough to just see what a material looks like in a 3”x3” sample chip and hope that it is what you want for a project. BIM affords design and construction teams the ability to not only thoroughly visualize, but quantify and qualify the material based on its merits and the design intent of the project. What I mean by this is the ability to embed computer readable information into a material that tells us not just what a material looks like, but what it “is” and how much of it is present on a project or in a given location. This is a tremendous benefit to both architects and contractors, giving them the ability to analyze product options and determine alternate solutions through cross referencing attributes.

Let’s suppose a solid wood material is specified on a project in order to provide the necessary density on a wall that is designed to reflect sound. Let’s also suppose that the wall has substantial curves, making the bending of the material very labor intensive, and potentially detrimental to the integrity of the wood. Rather than accepting the material at face value, researching materials in order to find an alternative product that achieves the required density, but is more flexible might lead the designer to a laminated material with a high density backer that meets the design intent, looks the same, and is less expensive. The difficulty in this type of operation is ensuring that the information about what the material is, how it performs, and what it looks like needs to be not only catalogued, but standardized.

The Construction Specifications Institute (CSI) develops and manages standards and formats that surround the AECOO communities, including MasterFormat™, Uniformat™, and the series of Omniclass Tables. The rapid growth of BIM creates a need to organize materials using not only methods understandable by people, but also by computers. To simplify, BIM software is little more than a series of tables in a database. These tables have relationships with one another, and in order to ensure that the connections are not broken by the use different colloquialisms or a varying taxonomy, each entry in a table should have some sort of unique identifier (GUID), or “primary key”. This is where CSI comes in. Just as MasterFormat catalogs the resulting effort of a given task, and Uniformat classifies entire elements within a project, Omniclass Table 23 – Products, and Table 41 – Materials catalog specific building products and materials so that regardless of the actual naming, a computer can understand what the user is referring to. It is no different than a librarian using the Dewey Decimal System to Catalog an entire library of books.

In terms of a library, the 200 Class (Level 1) within the Dewey system refers to Religion, with subcategory 220 (Level 2) referring to Bibles. There are entries beneath 220 which refer to the Old Testament (221) and New Testament (225), as well as other books which fall into the same category of “Bibles”. The word “Bible” needs to be put into context though, as the term has also been associated with anthologies and books that are designed to be all-encompassing, such as the AutoCAD Bible from Sybex Publishing. Even though libraries and bookstores have become keyword searchable, the Dewey Decimal system is still used to actually find the book or periodical within the larger bookstore or library, and create a singular reference for a certain type of book or specific title. This allows a machine to make a unique reference to a book, and only that book.

Similarly, a building product or material has the same hierarchical structure using Omniclass. Table 23 organizes products using four grouped pairs of digits, where the first is always the table number, in this case 23. As information is added, additional pairs may be added to further elaborate on the product. At the top level, table 23 products would look like this: – Products, and at its most detailed fifth level it might look like this: – Mail Slot. In this example, (Level 1) refers to “Openings”; (Level 2) refers to “Doors”; (Level 3) refers to “Door Components”; (Level 4) refers to “Door Accessories”. While one person might refer to the component as a “mail slot”, another might refer to it as a “postal opening”. Either way, the classification system will allow the user to choose the taxonomy while still allowing a computer to understand the intent.

Omniclass Table 41 – Materials performs the same operation, but rather than considering Building Products, it considers actual physical materials, regardless of their origin. It organizes materials down to their elemental level, which may not seem relevant, until you consider that specific chemicals may be banned from a project, or certain types of materials may be favorable. Table 41 uses the standard Omniclass “grouped pairs” format with Level 1 organizing materials into Periodic Elements, Solids, Liquids, and Gases. Level 2 through 5 dive deeper into the categorization of a material where level five refers specifically to Cast Iron, which is different from Wrought Iron ( or Ductile Iron (

Within each of these material and products, there are a series of attributes or physical properties which define what it is, how it behaves, how it performs, what it looks like, and a host of other considerations. Omniclass Table 49 – Properties creates a taxonomy that allows attributes to be given specific names and identifiers, making them uniform and machine readable. There are many different names which can apply to the same attribute, and a single character, capitalized letter, or mark in the naming will throw a computer for a loop. For instance, in some circles, the term U-Value is used, where in others, the term U-Factor is used. Those who understand what is being discussed may know that the two terms are synonymous, but a computer does not. By leveraging Table 49 and creating an enumeration strategy, one can assign specific attributes to building products and materials, and ensure that all of the information will show up in database reports, exports, and schedules.

With a membership base of Building Product Manufacturers, Architects, Specifiers, Engineers, and Contractors, CSI has more knowledge and experience than any organization in categorizing, classifying, and cataloging building materials. As the keepers of MasterFormat, Uniformat, and Omniclass, the expertise of the membership is implementing standards and formats for use in BIM software. This allows BIM software and processes to grow from visual design tools to data rich analysis and digital prototyping models. Structuring models to be useful for downstream usage requires that information be clear, concise, complete, correct, and consistent. It is arguable that without standards and formats developed and maintained by CSI, none of this would be possible.