Unveiling the Solar Chart: A Didactic Approach to the Geometry of Insolation through a Physical Model

Abstract

Hot and humid climates, with high levels of direct solar radiation, characterize much of the Brazilian territory. Thus, it is essential for students of Architecture and Urbanism to master the fundamentals of solar geometry in order to base design proposals that integrate climate change mitigation strategies. The solar chart, a traditional tool in the teaching of solar geometry, is a two-dimensional representation of an essentially three-dimensional phenomenon, mediated by a projection, often the stereographic one, which is unfamiliar to newcomers in Architecture and Urbanism courses. This results in complex explanations for instructors, abstract understanding for students, and little application of the concepts in design practice. The objective of this work is to develop a reduced and reproducible physical model to raise awareness among incoming students about the key concepts (solar altitude, azimuth, apparent solar trajectories throughout the year, stereographic projection, and solar charts) that govern solar geometry.