1-2-3 REVIT: BIM for Interior Design Options

11 Jan, 2006 Cadalyst

With BIM, interior designers and architects can evaluate multiple interior design schemes in the context of the rest of the building

Last month we began our exploration of how BIM (building information modeling) is being applied to interior design -- enabling designers to quickly and easily model and visualize the inside of a building. This month I'll focus on how interior designers can use BIM to capture and manage their design ideas as multiple options within a single building model.

Design Options
A designer often needs to keep multiple design alternatives open until enough information is available to decide between them. For example, a designer may need to track and compare an open office scheme providing daylighting and views with a more enclosed layout for programmatic and environmental comfort purposes.

A purpose-built BIM solution like Autodesk Revit Building supports design investigation by enabling designers to develop and study multiple design alternatives simultaneously within a single model. Design options can vary in their complexity, from additional floors in an office building to different flooring in a lobby (figure 1).


Figure 1. Autodesk Revit Building supports design investigation by letting designers study multiple design alternatives simultaneously within a single model.

You can toggle design options on and off in the model for visualization, quantification and analysis as needed. You can also maintain the options for as long as required (sometimes right through construction documents for bidding as alternates) and then incorporate, discard or archive them as key design decisions are made. You can create multiple sets of design options to address specific design issues. For example, one set of design options may focus on a floor layout while another set focuses on options for the lobby area.

Design options are all contained in a single Revit BIM. Users don't have to create separate models for the various options; they don't have to save as LOBBY_OPTION1 and LOBBY_OPTION2 -- as they would using CAD or Object-CAD solutions that rely on separate files or layers to store and manage data.

Revit Building coordinates the design information across all representations of the project and across all the design options for the project. All the views, schedules, material take-offs, drawings and so forth are direct presentations of the underlying building model. Thus, the design options are accurately reflected in related schedules, views and drawings.

Interior Design Options
To better understand how Revit Building uses design options, let's look at a typical commercial interior design job: a tenant fit-out project. The shell and core of the building is fixed, and the interior design team needs to define the interior space. The client has asked the designers to create three preliminary layouts: one featuring offices, a second with cubicles and a third open-plan with low/high partition walls.

Once the initial design options are developed, the client and architect meet to decide which proposal to pursue. They may base their decision on a variety of factors: space use, area requirements, aesthetics, material cost, daylighting analysis, etc. Supporting project material -- drawings, schedules, initial cost summaries based on material quantities, etc. -- are all used in the decision-making process. With Revit Building, this information is always available as live views of the building model, and the three design options are consistently reflected and coordinated in all related presentations. If an interior wall is deleted in a particular design option, the lighting sconce in that option is deleted as well, and the schedule of fixtures relating to that option is instantly synchronized.

As the design progresses, the client and design team selects the open-plan option and all the other options can be discarded. New options are then created to iterate on a more granular design. The material selection in the lobby area of our tenant fit-out example may interest the client, who wants to explore in greater detail various design options for that space using a mixture of material selections and finishes as well as several different furniture layouts.

Working with Design Options in Revit Building
The main Revit Building model encompasses all those features of the design that are not optional -- for example the shell and core of our tenant fit-out project. The selected design alternative is designated as the primary design option. By default, views display both the main model and the primary option. The design team on the tenant fit-out project had an inkling that the client would ultimately go with the open-plan option. So as they began their work, they designated that option as the primary design and the other two options -- traditional offices and cubicles -- were designated as secondary options.

You can control the visibility of design options in any model view -- plan, elevation, 3D, schedule, etc. -- using the Design Options tab of the Visibility/Graphic Overrides dialog box. If you aren't editing the options, a view displays the main model and the primary option by default. When you edit an option, the view displays the main model and the option that needs editing. You can also dedicate a view to a specific option within an option set by choosing the option name. Thus, Revit can display multiple design options side by side for reviews and client presentations -- and the alternate design schemes are accurately reflected in related schedules, views and drawings (figure 2).


Figure 2. You can evaluate alternate design options -- expressed in 3D views, drawings and schedules.

You specify which design option you want to work on by opening the Design Options dialog box, clicking Edit Option, and then from the pop-up menu, highlighting the desired option for editing (figure 3). The Edit Option button stays selected while you edit the option and when the cursor is placed over the button, a tool tip reminds you which option you are editing.

Figure 3. For quick access, you can browse and switch to any design option directly from the Revit Building toolbar using the Edit Option popup menu.

In our tenant fit-out example, the design team models the three specific floor layout options. They reference common elements of the main model (load-bearing and core interior walls for example) and create option-specific elements (office walls for the office option for example) that are visualized in option-specific views. By modifying the visibility properties of different views and schedules, the designer can toggle between the design options for day-to-day design tasks as well as client reviews.

A specific option is selected or the team can pick design pieces from several options to create the final proposal or proposals. The designer can delete or archive the abandoned options. The design team can create and explore new design iterations (such as the lobby area in our example) as the design progresses.

Achieve Consensus
The ability of BIM to capture and reflect design thinking enables interior architects and designers to evaluate, with their clients, multiple interior design schemes in the context of the rest of the building. As a result, less time is needed to achieve consensus on a particular design -- and the clarity and transparency of the process minimizes the number of change orders, the amount of rework and the impact of delays. BIM as a tool for design thinking translates into competitive advantage for interior design businesses.