Translating solar geometry through stereographic sun-path diagrams

a physical modelling approach

Abstract

The recurring difficulty in understanding stereographic projection and in reading solar charts compromises the assimilation of solar geometry principles within Architecture and Urbanism education programs and limits their subsequent application in the design process. This study presents the development of a reduced-scale didactic physical model that represents solar geometry by mapping a three-dimensional physical phenomenon onto a two-dimensional graphical representation through a solar chart based on stereographic projection. The methodological approach comprises five stages: (i) definition of form and materiality; (ii) interactivity and movable components; (iii) implementation of the stereographic projection; (iv) structural reinforcement and adaptation to different latitudes; and (v) preparation of supporting materials. The main contribution of this work resides in the development of a low-cost model, accompanied by open-source documentation, thereby facilitating replication and adoption across diverse educational contexts. The preliminary application of the model indicates potential for future investigations, particularly regarding material variations and the integration of lighting systems when the model is employed as a heliodon. Further validation studies using either robust quantitative or qualitative methodologies, or a combination of both, are recommended to assess its effectiveness within the teaching–learning process.