To what extent are the different types of diagrams used in designing projects? How do architects use diagrams? What are the impacts of the above-mentioned tool on the creative process of designing a building? These are the most important questions discussed in this article.

Background

The term 'diagram' has been used in architecture for a long time. Its etymology traces back to Greek roots and its use in architectural discourse has evolved considerably over centuries. In Renaissance architectural treatises, diagrams were already being employed as tools for design thinking, though they were primarily geometric constructions. The modern concept of the architectural diagram — as a mediating device between abstract ideas and built form — took shape more decisively in the twentieth century.

In Iran, discussion about the diagram as a design tool gained serious attention in the 1370s (1990s) and expanded notably in the 1380s (2000s). With the growing volume of theoretical texts translated from English and French, and with the increasing exposure of Iranian architects to international discourse through publications like El Croquis, Domus, and others, the concept of the diagram entered Iranian architectural vocabulary more prominently.

Types of Diagrams

Diagrams in architecture can be classified into several categories: functional diagrams that show spatial relationships and circulation patterns; conceptual diagrams that express the main idea or driving concept of a project; structural diagrams that illustrate load-bearing systems; and process diagrams that document design evolution. Each type serves a different purpose in the architect's toolkit.

The functional diagram, perhaps the oldest form, maps spatial relationships — adjacencies, separations, hierarchies, and flows. It translates the building program into a spatial logic. The conceptual diagram, by contrast, operates at a more abstract level, distilling the project's core idea into a visual shorthand.

Characteristics of the Diagram

What distinguishes a diagram from a drawing or a sketch is its level of abstraction. A diagram strips away material specificity — texture, color, exact proportion — to reveal underlying relationships and organizational principles. It functions as a bridge between analysis and synthesis, between understanding a problem and proposing a solution.

The diagram also serves a communicative function. It allows architects to share complex spatial ideas with clients, engineers, and collaborators in a language that transcends the technical specificity of architectural drawings. In this sense, the diagram democratizes architectural communication.

From Diagram to Form

The question of how a diagram becomes architecture — how an abstract organizational scheme acquires material presence — remains one of the central challenges of design. Some architects, like Peter Eisenman, have explored diagrams as generative tools that can produce form through systematic transformation. Others use diagrams more loosely, as orienting devices that guide but do not determine the final design.

What is clear is that the diagram, properly understood, is not merely an illustration or a representation. It is a thinking tool — a device for architectural reasoning that mediates between concept and construction, between the abstract and the concrete.