What does Building Information Modelling (BIM) mean for specifications?
by Ian Chapman
NBS Head of Specification
How many articles and posts do you read that include a definition along the lines of "BIM provides a 3D model of a building"? BIM is driving change but we should improve industry understanding of what BIM actually is. There's plenty of current debate and discussion on BIM and I encourage this greatly, but BIM is so much more than CAD geometries. Recent years have seen CAD vendors strongly promoting BIM products and to their credit they've produced some innovative tools, but for BIM to work we must consider the "i" in BIM more closely.
NBS treats BIM as a model containing all kinds of information, from spaces and geometry, to costs, programming, specifications and other information types. Specification documents have been around for centuries and little has changed in the way they are prepared; the output medium has evolved (papyrus, parchment, paper, PDF) but all have been written in a very linear way. BIM and data modelling techniques offer the opportunity to do something different which, for specifications, means a big change.
We know that BIM means general change in construction industry working practices; it also means change in specification writing practices by NBS technical authors. In the past when NBS created or maintained its master specification, authors dealt with important matters such as reflecting industry practice, relevance, standardization, availability and quality. On top of this, we now spend time looking at the structure and digital organization of specification content. NBS content has always been precise in what it says, but now it is organized with precision; strict rules followed by technical staff will ensure flexibility, interoperability and options for customers. We have authoring rules on what a system is, what a product is and how they relate to each other, which at times can lead to some debate, for example: "Is a window a product or a system?" Well it can be both and NBS must reflect this. The window can be a combination of many components from different manufacturers coupled with specialist site activities for building-in the frame; or it can be an assembly that is bought entirely from one manufacturer, fully glazed and complete with hardware and flashings – an off the shelf product if you like. NBS reflects these options already in section L10 from a technical perspective, but we need to be more defined in how this content is structured to enable integration with other BIM tools. Product specifications should relate to the systems they belong to, and both should relate to other BIM information types such as geometry and cost. Precisely defining NBS content will allow this information to be shared and connected to other information types, and make BIM happen.
If NBS is changing the way it authors content, what does that mean for project specifications? We are at the point where it feels like there are no limits to what can be done once our content is strictly organized and with intelligent relationships defining what goes with what. Some examples of what should be possible include:
- Specifications can be created at any point along the project timeline. Early stage specifications such as outline reports can be prepared and information documented at that stage will flow into the outputs of subsequent project stages, e.g. performance specifications and full specifications. Apart from the time saving of not having to retype specification information from one stage to the next, decisions made at outline stage, for example which systems are used and their product choices, can allow more detailed specifications to be assembled automatically. Allowing the specification model to grow in this way, building on previous specification decisions, will lead to more consistent output documents, with less room for error or information going missing as work proceeds from stage to stage.
- Systems selected at outline stage are part of the information model and therefore will already be part of the performance or full specification. Quicker specification assembly will be welcomed by specifiers, but more relevant and concise specifications will be welcomed by all.
- Avoiding duplication of information in project specifications becomes possible when NBS content is organized and assembled using a clear structure.
- Strongly related specification content will include the ability to integrate with other BIM content such as CAD geometries and quantities, making costing, compliance checking and progress tracking possible.
- A variety of reports or views of the specification model become available. Reports describing everything about an entire system are possible at the click of a button as are reports on colour choices across multiple systems and product centric reporting such as "tell me everything about the plasterboard specified on this project".
Creating specifications using NBS has so far been a very linear process – you start at the top and work your way through all clauses by including or excluding them until you reach the end. With information modelling there is no top or bottom; you populate the model by making decisions and, depending upon the choices made, other choices become available, some of which you will use, others will be "parked" for use later on in the project.
Finally, for those wondering "Will BIM replace NBS?" The answer is absolutely not. Specification information is an essential component in the information model, it describes the requirements and outcomes for the project and this information will always be necessary. Industry doesn't yet have all the BIM answers it needs, issues surrounding liability, Intellectual Property Rights, digital information exchange and ownership are examples of current uncertainties. In time these will be resolved and specification information which is a big part of the "i" in BIM will be very different to the ring bound, card covered paper documents in use today.
If you'd like to learn more about what we're doing and understand what's in store for NBS specifications, feel free to get in touch by email firstname.lastname@example.org.
Related NBS information:
- How to reference NBS specifications in a CAD drawing
- BIM - The long view from architectural and design practice
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