SOLAR POSITION
Sun’s movement through the day/year is a
critical environmental factor that needs to be
understood to design a high performance
building
 Planned correctly, you can take advantage of
the sun’s path
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 Natural
daylighting
 Passive heating
 Photovoltaic energy generation
 Natural ventilation
SOLAR POSITION
Altitude – vertical angle the sun makes with the
ground plane
 Azimuth – horizontal angle between the
sun and true north (-180 degrees,
180 degrees, positive in a clockwise
direction from north)
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SEASONAL VARIATIONS/IMPORTANT DATES
Sun’s path varies throughout the year
 Summer – sun is high and rises/sets north
of east-west (northern hemisphere)
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 south
of east-west (southern hemisphere)
 Rises much earlier and sets much later in the
summer than the winter
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To plan for the extreme heat in the summer
study the summer solstice
 Sun
is at its highest noon altitude
SEASONAL VARIATIONS/IMPORTANT DATES
Winter sun is low in the sky
 Rises/sets south of east-west (northern
hemisphere)
 Rises/sets north of east-west (southern
hemisphere)
 To study extremes of winter look at the sun’s
path during winter solstice, sun is at its lowest
noon altitude
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SEASONAL VARIATIONS/IMPORTANT DATES
To study more average positions look at the
sun’s path on the spring and autumn
equinoxes, sun rises and sets due east-west
 Altitude of the noon sun at the equinox is
determined by the latitude of the site
 Rule of thumb for optimum angle of solar
panels is the latitude of the site, rays are most
perpendicular to the panel for most of the year
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TIPS/RULES OF THUMB
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Study particular days
 Solstices:
extreme of the sun’s position
 Equinoxes: average sun position
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Study different seasons:
 Winter
studies – How to maximize sun to passively
heat the building
 Summer studies – How to minimize sun to
passively cool the building
DATES TO REMEMBER
LOOK AT SOME SPECIFIC TIMES OF DAY
Morning – try to capture the sun’s energy to
warm up spaces when the sun is low in the
sky, need to protect against glare
 Noon – Strongest and highest in the sky.
Avoid hot midday sun to reduce cooling
loads. May want to capture the sun for
passive solar heating/energy generation
 Afternoon – Prevent overheating/glare
 Occupancy hours – Think about when the
building is used most
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STEREOGRAPHIC SUN PATH DIAGRAMS
Used to read solar azimuth and altitude
throughout the day
 Like a photograph of the sky, looking straight
up towards the zenith with a 180 fish-eye lens
 Paths of the sun at different times of the year
can be projected onto this flattened
hemisphere
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HOW TO READ STEREOGRAPHIC SUN PATH
DIAGRAMS
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Used to read solar azimuth and altitude
Azimuth lines- angle lines run around the edge of the
diagram
Altitude lines – represented as concentric circular
dotted lines that run from the center out
Date lines – Start on the eastern side of the graph
and run to the west. Represent the path of the sun
on one particular day of the year
Hour lines/analemma – shown as figure 8 lines that
intersect the date lines and represent the position of
the sun at a specific hour. Intersection between date
and hour gives the suns position
READING THE SUN POSITION
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Locate the required hour line on the diagram
Locate the required date line (solid lines are Jan-June
and dotted July-Dec
Find the intersection point of hour and date lines (solid
with solid, dotted with dotted)
Draw a line from the very center of the diagram through
the intersection point to the perimeter
Read the azimuth angle take clockwise from the north
Trace a concentric circle around from the intersection
point to the vertical north axis, displays altitude angle
Interpolate between concentric circle lines to find altitude
Gives suns position as defined by azimuth and altitude