A Procedure for Plotting the Sun-Path Diagram, and Shading Mask Protector

Abstract

The well-known versions of sun-path diagrams and shading mask protractors that appear in the AIA`s Architectural Graphic Standards (Ramsey and Sleeper, 1970) are based on the equi-distant projections and use the shading mask protractor developed by Olgyay and Olgyay (1957). A designer using the AIA`s Graphics Standards book, or other versions of the sun-path diagram (LOF, 1974; Mazria, 1979) must select the nearest latitude, make photocopies of the appropriate sun-path diagram and shading mask protractor, and then overlay the shading mask protractor upon the diagram in the proper orientation. The 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 sun-path diagram to determine if a point at the base and center of a window is exposed to direct sunlight. This technical note describes the basic equations that can be used to develop a computerized construction of the shading mask protractor and sun-path diagram, and demonstrates their use with an example shading device at a northern latitude. A brief historical review of the sunpath diagrams and additional information regarding the computerization of the diagrams is provided inmore » McWatters and Haberl (1994a,b).« less