 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  Natural daylighting  Passive heating  Photovoltaic energy generation  Natural ventilation

 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)

 Sun’s path varies throughout the year  Summer – sun is high and rises/sets north of east-west (northern hemisphere)  south of east-west (southern hemisphere)  Rises much earlier and sets much later in the summer than the winter  To plan for the extreme heat in the summer study the summer solstice  Sun is at its highest noon altitude

 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

 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

 Study particular days  Solstices: extreme of the sun’s position  Equinoxes: average sun position  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

 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

 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

 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

 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