In a 1954 report entitled Application of Climatic Data to House Design, brothers Victor and Aladar Olgyay introduced the Shading Protractor. They showed it on the cover of the report, along with a reference to neoclassical French principles of composition, and the intelligent shading of the Brazilian Ministry of Education building by Oscar Niemeyer and Le Corbusier:
In a 2014 article**, David Leatherbarrow and Richard Wesley interpreted the graphic design above for its cultural meaning. They wrote:
"That the Olgyays chose a Classical drawing of the profile of a human face and positioned it so that it appears to be gazing at the sun screen of a modern facade through the lens of a shading protractor represents a provocative proposition: building elements designed in precise reaction to environmental factors could become the ‘visibly evident’ elements of a new architectural style equivalent to the Classical."
Protractor-like tools had been used earlier to understand solar geometry and shading* but the Olgyays' developed "Shading Masks"—a new method of graphic representation to understand solar gain and design proper shading. In their 1957 book Solar Control and Shading Devices, they established the following procedure:
Step 1: To determine the times when shading is needed.
Step 2: To determine the position of the sun, when shading is needed.
Step 3: To determine the type and position of a shading device which will interfere between the sun and the point of observation during the overheated period.
Step 4: To design a shading device from the shading mask.
While the Shading Mask is a generative tool for design in the procedure above, it could also be used to analyze existing designs. In the same book the Olgyays created Shading Masks for various case-study buildings in various locations. Here are some samples which correspond to actual shading devices of different types:
As Leatherbarrow and Wesley noted, the Shading Protractor has been "long since replaced by computer simulation."
*See Tools: Whit Smith's solar tool and Tools: Libbey-Owens-Ford's Sun Angle Calculator
**David Leatherbarrow and Richard Wesley, "Performance and style in the work of Olgyay and Olgyay," arq: Architectural Research Quarterly (2014).