2020 | 020 – Conceptual Design Strategies – Geometric Constraints and Requirements

By Eric Bobrow

Mar 26


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ARCHICAD Training Lesson Outline

Conceptual Design Strategies - Geometric Constraints and Program Requirements

Today we'll look at a variety of methods and tools useful during initial design.

Each project begins with certain constraints and program requirements that need to be fulfilled and optimized. 

Geometric constraints include setbacks, height limits and floor area ratios, with additional considerations for budget, materials, historical style and time frame. 

Program requirements include numbers, types and sizes of rooms and spaces, location and proximity of these spaces, access and circulation, orientation and view corridors, as well as lighting, fenestration and style.


Jared Banks uses an interesting term for the constraints and limits on a project that he calls "invisible forces." These are not seen in the final model, but play an important role in shaping the design.

Setbacks and clearances from property lines and other boundaries are important considerations. The polyline tool (similar to polygon-based tools such as slabs, fills and roofs) can be offset uniformly using a command in the Pet palette. 

One can trace the boundaries with the magic wand to create a copy of the original polyline, then select and offset the edges. It is also possible to use the Window menu > Palettes > Control Box to select an Offset and draw new lines or polylines in a single operation. Other drafting control variations in this palette include multiple offset, perpendicular and parallel constraints.

The Fill tool may show a shaded or hatched area and has an option to calculate and display the area as text. This can give instant feedback on the lot area as well as the building footprint or any bounded polygon. The fills can be color-coded to show usage or communicate other information visually, and areas may be totaled and reported (this will be explored in future lessons).

The Zone tool can automatically fill a room, seeking out the bounding walls, or be drawn with a manually created outline. It has a stamp that reports information such as the room name and number, and calculated values such as area and volume. Zones can be used to total up and report usage to compare against program requirements. They can also be created as independent graphic components that can be moved around to study different configurations while maintaining the right number of spaces as laid out from the program.

Zones may be viewed in 3D as part of the building model when the control for this is turned on in the View menu > Elements to Show in 3D > Filter and Cut Elements in 3D. In fact, one can turn off other element types in this dialog, and just view the Zones in 3D, which allows them to be displayed and reviewed for stacking and blocking studies.

Slabs may be used for creating volumes for massing study, depicting multi-story spaces with simple or complex outlines. Different colors or materials may be used to represent usage, phasing or exterior treatments.

Morphs can be used in a similar fashion, with the advantage that their shape can be manipulated more freely. It is possible to calculate and report floor areas for the morph at each story level, facilitating program analysis for complex designs.

Some designers like to sketch out a building concept with single lines representing the shell and partitions. A productive alternative is to use the wall tool with a 0 thickness, since it is just as easy to draw as lines yet it may be viewed in 3D. In addition, the walls may later be given a nominal or actual thickness, and eventually take doors and windows, which would be impossible with a single line diagram.

Ultimately, all of these tools and approaches are useful, and it is important to become familiar with most or all of them. This will give you the flexibility to take on your design challenges with finesse, applying the most useful tools for each part of the process.

ARCHICAD Training Lesson Transcript

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