The common data environment (CDE), is the single source of information used to collect, manage and disseminate documentation, the graphical model and non-graphical data for the whole project team (i.e. all project information whether created in a BIM environment or in a conventional data format). Creating this single source of information facilitates collaboration between project team members and helps avoid duplication and mistakes.Ownership of information within the CDE remains with the originator of that information. Individual models produced by different project team members do not interact, they have clear authorship and remain separate. This means that the liabilities of the originators are not changed by the incorporation of their model into the federated model. There may be complications however where ownership changes as the project progresses, for example replacing design team objects with specialist sub-contractor objects.
Generally, a licence is granted to the client to use the information contained in the separate models for the ‘permitted purpose’ (ie for the purpose for which that level of detail of information was intended). A sub-license from the client enables project team members to use models prepared by other project team members.
The BIM protocol proposes that an information manager, appointed by the client, should set up and manage the common data environment. The information manager is essentially a procedural gate-keeper, policing the common data environment to ensure that it follows the agreed protocols and that the data is secure. They are not a BIM co-ordinator and have no design responsibility and no responsibility for clash detection or model coordination.
The common data environment may include a number of different information environments. It may include a supply-side common data environment used by the project delivery team, and an employer’s information environment that provides an employer-side document and data management system for the receipt, validation and approval of project information delivered by suppliers.
The Emplyers Information Requirements states that for information management for the capital/delivery phase of construction projects using building information modelling, suggests that a CDE may use a project server, an extranet, a file-based retrieval system or other suitable toolset.
It proposes that the advantages of a CDE are:
- ‘Ownership of information remains with the originator, although it is shared and reused, only the originator shall change it.
- Shared information reduces the time and cost in producing co-ordinated information.
- Any number of documents can be generated from different combinations of model files.’
And that, ‘ If the procedures for sharing information are consistently used by the design teams, spatial coordination is a by-product of using the CDE processes, and will deliver production information that is right first time… It provides the ability to produce traditional drawings or documents as views of multiauthored data within the CDE. It also gives greater control over the revisions and versions of that data.’
Information within the CDE can have a wide variety of status levels, however there will generally be four main areas of information, with a sign-off process allowing information to pass from one area to the next:
- Work in progress (WIP). This area is used to hold unapproved information for each organisation.
- Shared (or client shared) area. This information has been checked, reviewed and approved for sharing with other organisations, perhaps including the client.
- Published: This information has been ‘signed off’ by the client or their representative (often the lead designer).
- Archive. This area is used to create a record progress at each project milestone as well as all transaction and change orders.
A typical structure is illustrated below.
Whilst this may sound complex, on small projects, the CDE might simply be common folders on server, or may use a free, web-based file sharing application. Even on large projects, where sophisticated software might be used, during the early stages of the project it might simply be matter of creating four folders in which files are stored, with files named in accordance with a standard naming protocol such as that outlined in BIM Execution Plan.
It should be noted that the CDE itself is not collaboration tool, although it may be used with one or more collaboration tools.