New educational software for teaching the sunpath diagram and shading mask protactor

The well-known versions of the sunpath diagrams that appear in the AIA’s Architectural Graphics Standards are based on the equidistant sky dome projections and use a shading mask protractor developed by Olgyay and Olgyay at Princeton University in the 1950s. A designer using the AIA’s Graphics Standards book, or other printed versions of the sunpath diagram, must select the nearest latitude, make photocopies of the appropriate sunpath diagram and shading mask protractor, and then overlay the shading mask protractor upon the diagram in the proper orientation. he outline of the shading device is then transcribed upon the shading mask, aligned at the proper orientation for the facade in which the window is being analyzed, and placed on top of the sunpath diagram to determine if a point centered at the base of the window is exposed to direct sunlight. Teaching this process to architects and engineers is tedious and error-prone since the students must calculate several angles and then mentally translate their cartesian coordinates onto a sperical coordinate system to determine whether or not their shading device is going to have the intended effect. As a result of this, the sunpath diagram and shading mask protractor are not widely used because many designers either do not understand how to use the tools or do not budget the time to analyze a shading device properly with these tools. This paper describes the new MS-Windows-based educational software package (Oh and Haberl 1996) that has been developed to fast-track the learning of the sunpath diagram and shading mask protractor which is based on previously published equations for plotting the sunpath diagram and shading mask protractor (McWatters and Haberl 1994a, 1994b, 1995). A review of the manual process is also provided to compare the computerized tool to the traditional design method.