Integrating the specifications with a building information model fulfils one of the great promises of BIM; to be able to use a single point of reference to facilitate and coordinate complimentary processes. However it also raises fundamental questions regarding information management. For example, how can multiple parties access the same model element simultaneously, and what is the (useful) extent of information that can be embedded in a model?
In reality it is not possible for two parties to modify the same element simultaneously, however it is possible for different parties to access distinct parameters within the one component. One way of achieving this is by locating certain parameters outside of the central database. The ancillary parameters are live-linked to the original component, but can be worked on independently. Essentially one is establishing a multiple database structure; a central database of core project information – ie the building model - and secondary databases of domain specific information. This isspecialised, as may be the case with specifications, and the information need not be contained in the model element itself.
This methodology achieves multiple ends:
- Increases the over-all data content of the BIM (without over-burdening the original database)
- Enables multiple users to have access to different levels of information and functionality, depending on their role in the project team.
- Ensures that all project parties have access to the same core project data, at the same time.
LINKING THE DATABASES
Linking two databases (for example the BIM and the specification) must occur at a component level. Furthermore, the association must be flexible enough to accommodate changes in either database, while maintaining and updating the link.
The link between the model elements and the specifications can be a semi-automated process. One strategy is to pre-define relationships by binding individual model elements to related sections from a specification master document, prior to project modelling. As the elements are placed in the model the corresponding sections are drawn from a master specification database and compiled in the project specification manual. Throughout the life of the project, a live link is maintained between model and specification, so that changes in the model will be automatically reflected in the specification, and vice versa. Depending on the ‘rights’ of the project member, they would be able to access, review and even redline the specifications associated to a particular assembly by clicking on the element instance in the building information model. Viewing linked specifications via the selected instance in the model can be very useful for downstream functions such as estimating, construction management and facilities management.
Depending on the ‘rights’ of the project member, they would be able to access, review and even redline the specifications associated to a particular assembly by clicking on the element instance in the building information model. Viewing linked specifications via the selected instance in the model can be very useful for downstream functions such as estimating, construction management and facilities management.
HOW IS THIS ACHIEVED? - MODEL MAPPING
Building models are typically described as assemblies, based on internationally recognised standards of classification such as UniFormat, MasterFormat or OmniClass, among others. Such classification systems provide a consistent way to define building model components, regardless of the complexities of the assemblies or model elements that they represent.
It is also a very logical way to categorise building model elements as we tend to think about the components of the building as assemblies rather than constituent parts.
UniFormat is an industry standard classification system, developed in part by the Construction Specifications Institute (CSI), used primarily as a way of categorizing information about building elements which may contain multiple detailed parts. As defined by the CSI, “UniFormat is a method of arranging construction information based on functional elements, or parts of a facility characterized by their functions, and often referred to as systems or assemblies. It is a way to organize information about an entire assembly with multiple detail components.”
Specifications, on the other hand, are structured according to products, activities or construction requirements. In North America specifications are based on MasterFormat, a 50-division, material- specific organizational format which, according to the CSI, is an “organizational standard for specifications and is a master list of titles and numbers classified by work results for organizing data about construction requirements, products, and activities.”
The mapping tool must understand the logic of both databases and establish a flexible association. This can be achieved by creating ‘bindings’ - logical associations between the model assemblies and the corresponding sections of the specification master document.
The BIM-integrated specifications process should ‘construct’ the specifications according to project- specific conditions, such as location or building type. This accommodates the variation in specifying a particular element depending on whether the building were a gaol or a school, or whether the project were located in Abu Dhabi or Zurich. The process involves defining specific ‘accounts’ (eg for school or gaol) and then activating these accounts, like a filter system, to modify the individual bindings.
Leadership in Energy & Environmental Design (LEED) is, according to the U.S. Green Building Council that developed it, “an internationally recognized green building certification system that is providing third‐party verification that a building or community was designed and built using strategies aimed at improving performance across all the metrics that matter most: energy savings, water efficiency, CO2 emissions reduction, improved indoor environmental quality, and stewardship of resources and sensitivity to their impacts.”
LEED certified designs require additional information to be incorporated into the construction specifications which can add to the time and cost to prepare the specifications as well as to increase the chances that the models and specifications will be misaligned and out of sync. BIM-integrated specifications can reduce the additional cost and complexities associated with LEED projects by automatically filtering the master specifications for LEED specific language. MasterSpec, for instance, includes hundreds of sections with LEED requirements text and commentaries, including six Division One LEED‐related sections. By setting up a Client Account for LEED projects, this specific LEED language can be associated through additional bindings to model elements that in one way or another require additional LEED information to be incorporated into the specifications. For instance, in the Wood Window section, there is additional specification language required for “manufacturer’s qualification” and for “certified wood” if the wood windows are to be LEED certified. The simple inclusion of these additional options in the LEED Client Account bindings will insure that the languageis added to the specification manual as required. Furthermore, one is able to associate specification sections to elements that are not modelled. It is often not practical to model detailed elements, although the relevant specification sections would still be required. This can be overcome by manually binding the additional spec sections to the model assembly as required. A more controlled way of dealing with this would be to include the detailed elements within the model assembly as parameter field, with no geometric counterpart. The specifications can then be bound to these parameters.
General specifications sections that have no component reference can also be bound to a project. This could be a manual process, or it could be structured to reference general project information, such as facility type.
AUTOMATION AND SYNCHRONISATION
Automating the preparation of the project specification manual can be of significant value to a project team in increasing speed and efficiency, however the greatest benefit is in ensuring that the models and specifications are synchronised. Even the slightest oversight or ambiguity in the construction documents can lead to time consuming and costly change orders if these things are not discovered before construction begins.
BIM integrated specifications provide an example of the one of the great promises of BIM, to be able to use a single source of information to facilitate and coordinate complimentary processes. It also demonstrates a practical data management process, where content and functionality can be managed to respond to distinct requirements of the various project participants.
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