Modelling Design Intent

Project models are developed incrementally. More detail is added to a model as a project progresses.

Projects will start with just an architectural model, with limited detail. More detail will be added to the architectural model and additional models will be provided from other designers, all adding to the available detail.

An early architectural model will include design intent for structural elements and spaces or volumes for the routing of building services. As detail is provided from other designers the early architectural design intent should be removed from the architectural model.

Update Models to Prevent Duplicate Components

However, all too often the initial design intent items are retained. Resulting in duplicate components and unnecessary clashes.

For example, an early architectural model may detail the permitted or preferred location of structural columns. The structural engineer then designs a structure to fit within the bounds or the parameters provided within the architectural model. This is the correct way to develop a design (and as recommended within PAS 1192-2). But what should happen next is that the architect, takes the structural engineer’s model and checks it for compliance with the initial outline design. Confirming that columns are located in allowable positions and contained within the available volumes.

This also applies to many other items. It could be structural slabs, structural beams, volumes for primary service runs and specialist subcontractor design items (such as curtain walling and cladding). Items initially provided as an outline design should be replaced by detailed design models after an initial check for compliance.

When design items are not removed we end up with duplicate components. This results in unnecessary model issues and larger than required model files.

Archiving Design Intent

Designers should not remove their design intent components until they are fully satisfied that the detailed design items fully meet the design requirements. And in many cases, designers will want to archive their initial design intent by retaining design intent elements in a separate model or volume.

But what is important is that design intent items should not be provided within shared models after detailed design models, for those elements, have been reviewed and verified.

It is a simple process that will improve BIM design workflows and ensure that information is developed in a rational and organised way.

Developing Design Intent

Created with Raphaël 2.1.2Lead Designer – Design Intent ModelledSpecialist Designer – Detailed Design ProducedLead Designer – Checks Suitability of Detailed Design Lead Designer – Design Intent Removed from Federated ModelFederated Model Produced Without Duplicate Models

The original design should not be entirely removed, it may need to be referenced if the detailed design undergoes significant changes. Instead, it should be archived or transferred to a separate model volume that does not form part of the federated model.