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).