This chapter begins by noting the importance of understanding the sun’s position to site planning and the design of daylighting systems, passive solar heating systems, and passive and active cooling systems.
Solar patterns are an important context for architectural design.
Properties of the sun and its resulting radiation are discussed. The geometric interactions between the sun and the earth during the year are considered. The altitude and azimuth angle are identified as key measures of the sun’s position relative to a location on earth and the cyclical pattern of these angles over the course of a year are presented. The critical distinction between clock time and solar time is noted; the clock time oddity of Daylight Saving Time is discussed. The difference between true (solar) south and magnetic south is flagged. Various types of sunpath projections are presented and their application to design situations discussed. These include sunpeg diagrams and horizontal and vertical projection sun path diagrams.
Shading is addressed in some detail. Fixed shading optimized for orientation and movable shading devices are considered. Numerous diagrams and built examples of shading devices are presented.
Shadow angles and shading masks are introduced as design tools to assist in the design of shading devices. An analysis of a horizontal shading device is included. Various design approaches for shading devices are considered.
6.1 The Sun and Its Position
(a) Earth’s rotation and tilt
(b) Altitude and azimuth
6.2 Solar versus Clock Time
6.3 True South and Magnetic Deviation
6.4 Sunpath Projections
6.5 Shading
(a) Shading for orientation
(b) Operable shading devices
6.6 Shadow Angles and Shading Masks
(a) Shadow angles
(b) Shading masks
(c) Use of shading masks
(d) Designing finite horizontal shading devices
(e) Design approaches
References
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 solar insolation (as a sometimes resource and unwanted burden) solar position (as ways o f relating the sun’s location relative to objects on Earth) solar versus clock time (as critical to the use of sunpath diagrams) solar versus magnetic south (as critical to the use of sunpath diagrams) types of sunpath projections (as defining the form of these diagrams) shading devices (as a design method) shading masks (as a design tool) physical models (as a design tool)
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Important Terminology
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 solar constant insolation radiation spectrum declination altitude angle azimuth angle (bearing angle) solar time clock time time zone equation of time
Daylight Saving Time true (solar) south magnetic south analemma sunpath projections gnomonic sundial sunpeg chart equidistant horizontal projection sunpath chart rectilinear
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 vertical projection sunpath chart stereographic fisheye projection skydome shading devices fixed movable eggcrate horizontal overhang vertical fin vegetation shading mask 
 shadow angles vertical shadow angle (HSA) horizontal shadow angle (VSA) profile angle
 Sun Angle Calculator (Pilkington)
Important Metrics
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 various solar position angles (degrees) solar and civil times (hours)
Square One Research (solar position tutorial):
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http://www.squ1.com/index.php?http://www.squ1.com/solar/solar-position.html
Geomagnetic Maps (showing magnetic deviation): http://www.geo-orbit.org/sizepgs/magmapsp.html
Sundials.org (information on clock vs. solar time): http://sundials.org/faq/tips.htm
University of Oregon (sunpath diagram software): http://solardat.uoregon.edu/SunChartProgram.html
Online sun angle calculator: http://www.susdesign.com/sunangle/
U.S. Naval Observatory (complete sun and moon data for one day) http://aa.usno.navy.mil/data/docs/RS_OneDay.html
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