What is BIM

BIM (Building Information Modelling) is a term continually thrown around in the industry today. Unfortunately, few sources clearly identify what it is. Sometimes doing the opposite and pigeon-hole it into such a narrow scope; few projects can go down that road. We also often read (and I have sometimes said), “BIM has different meanings to each person you speak too”.

I actually don’t think it’s that complicated. Most BIM “experts” would be happy to agree with the following simple approach: “BIM is a process involving building data management, with a level of spatial understanding”. However, stakeholders may have very different expectations of BIM outcomes or deliverables.  This is nothing new! Building owners, Architects, Engineers or Contractors will view a building very differently. Thus; why should BIM outcomes or deliverables be any different?

So let us focus back on just BIM? BIM outcomes are another discussion. The below statement is my current approach and is a manipulation of the Wikipedia overview (May 2013). 

My BIM Definition:
Building Information Modelling (BIM) is a managed process, involving the recording, exchange, and application of pre-defined, trusted, structured digital data; representing physical, functional and spatial characteristics of a facility.

Let’s look at some of the keywords within:

Managed Process: 
Implies a planned (documented steps) set of supervised actions occurring with a specific end goal. Process Mapping becomes an integral aspect of BIM and is created to roadmap each outcome.

                      Above Image extract from Penn State BIM Execution Plan

The goal of the process cannot be overstated. Without a goal, there is no point in BIM. This makes a mockery of projects where a client just asks for “BIM” on their project.

Data Recording: 
During the production of any product, a substantial amount of information is generated and collected. The benefit of recording all relevant information to one place (single entry) and populate multiple outputs is the first principle of BIM.

Data Exchange: 
At the core of BIM lies the transfer and sharing of reliable data with minimal degradation.  BIM has many Information Exchanges, including COBie (Construction Operations Building Information Exchange) and IFC (Industry Foundation Classes), just to mention a few. The basis of any information exchange is to maintain data fidelity when transferred between parties or software applications. This information exchange requires careful management.

Above:  Information transfer between parties. Source: BIM Handbook: A Guide to Building Information Modelling for Owners, Managers, Designers, Engineers and Contractors. Authors: Chuck Eastman, Paul Teicholz, Rafael Sacks & Kathleen Liston.

That is, the generated / exchanged data has a specific use and purpose.

In order for any process to truly work the parties involved need to understand exactly what data is generated, by whom, when is it exchanged, how it can be used, does it require maintaining and if so my whom. BIM Management Plans, Level of Development tables and other matrixes may be used to map these out.

Trust between parties is one of the cultural difficulties very evident in the building industry. Yet, for BIM to work, trust is an integral part. So how do we develop trusted data?
It relies on open, quality control, i.e., the recipient of the data can clearly see how the data author is checking and maintaining the information.

An example of this as part of a deliverable is within the COBie 2 specification: Section 1.1.4 Clause “C”:              The contractor shall check all COBie2 files prior to submission, regardless of the source of those files.  The Contractor shall submit a brief report with each COBie2 deliverable indicating steps taken to verify compliance with the COBie2 format.

Structured Digital Data: 
We have been exchanging digital data about buildings since computers came into the office. However it is rarely truly structured, i.e. the naming, formatting, and generation is defined and thus consistent.

A building information model is a virtual prototype of a building at a specific time during its lifecycle. It is an accurate representation of the building, within its fit for purpose.

Elements in a building information model are to be object orientated, and thus have rules on how they perform in the built environment. This may be as simple as doors understanding they can only be hosted in a wall, to windows containing detailed thermal properties, allowing for heating analysis.

Every element within the BIM (model) must have some spatial awareness or geometric coordinate. I.e. understanding what space/rooms it’s in (e.g. a COBie workbook) or an x,y,z and orientation coordinate (e.g. code checking model).

The concepts of BIM are not restricted to buildings, but can be extended to anything in the built environment. This may include, but not limited to;  buildings, structures, bridges, roads and infrastructure etc.

Some changes to the definition over time:
As we are not within the Science realm, the exact wording of definitions develops over time. There are some obvious wordings which are now left out from current BIM definitions:

Entire Lifecycle: 
In some past definitions, the word whole Lifecycle was used. In reality, there are few buildings were BIM is engaged from pre-planning, design, construction, re-development, decommissioning and disposal. It will take about 45 years before anyone can say they have achieved this. What is also missed, a BIM could be used after demolition, for future planning. BIM occurs during a part of the lifecycle but does not need to include all of it. There is also an emerging philosophy which state “Control Cycle” is really the goal is: Refer to Unified Theory of BIM – Bill East – Youtube:

In many cases, a 3-Dimensional Model is just a by-product, or a part of the journey to develop an initial BIM data. A MS Excel workbook (e.g. COBie data) containing component data and their spatial location can be considered a BIM.

Little BIM: 
If we remove any of the key words from the above definition, the result is often referred to as Little BIM. Little BIM may not be as flashy, but is a vital step for firms building systems to provide a BIM service. I would be as bold to say; “if you can’t do little BIM well, you will not be able to deliver (Big) BIM”. Little BIM can be seen as a method to improve QA, efficiencies, communication and coordination.

As BIM is fundamentally a process, any BIM deliverables taken on board, result in business and workflow change. Nobody wants a micromanaged project, thus team familiarity to Little BIM, before Big BIM deliverables is essential.

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