ARCH 400: Solar Geometry and Climatic Design

• ARCH 400 is a Climatic Design course.
• Arch. Jiffer John L. Taala is the instructor.

Solar Geometry

• Sun Path Diagram
• How to Read the Sun Path Diagram
• Basic Calculation on Shading Devices.

Three-Tier Design Approach

• Tier 1: Basic Building Design involves conservation, heat avoidance, and daylighting.
• Surface-to-volume ratio, insulation, and infiltration are key in heating conservation.
• Shading, exterior colors, insulation, and mass are factors in cooling.
• Windows, glazing type, and interior finishes are considered in daylighting.
• Tier 2: Natural Energies and Passive Techniques
• Passive solar (direct gain, Trombe wall, sunspace) utilizes natural energies for heating.
• Passive cooling (evaporative cooling, night-flush cooling, comfort ventilation) employs natural energies.
• Daylighting via skylights, clerestories, and light shelves harnesses natural energies.
• Tier 3: Mechanical and Electrical Equipment is for heating & cooling and renewable energy with lighting equipment

Sun Path Diagram

• Graphical representation that shows the sun's trajectory across the sky at a specific location throughout the day and year.
• Illustrates solar positions during sunrise, sunset, and various times.
• Uses: solar energy studies, architectural design, and understanding sunlight exposure.
• A sun path chart plots the sun's elevation and azimuthal angles for different days of the year at a given location.
• Elevation angle: Measure of the sun's height in the sky from the horizon (0°) to straight up (90°).
• Azimuthal angle: Measure of the sun's (North/East) location in the horizontal plane.
  • North: 0°, East: 90°, South: 180°, West: 270°.
• Sun path charts are useful in identifying obstructions to direct sunlight on collectors.
• Site analysis requires a compass and a clinometer.
• Compass determines the azimuthal angle; a correction is needed to find true north.
• Clinometer determines the angular height of an object, providing elevation angles of obstructions.
• Obstruction locations can be drawn on the sun path chart to determine shading duration and days.
• TMY2 database is used in shade analysis to estimate electricity output from photovoltaic systems.

Reading a Sun Path Diagram

• First, find the applicable month on the chart.
• Then locate the time needed on the chart for the particular month.
• The intersection of elements on the chart equals the position of the sun being sought.
• Solar altitude is determined by the circular lines on the map.
• Azimuth, or direction, is determined by intersection of the center of the cartesian plane with the point being sought and read from north at 0°.

Shading

• Horizontal shadow angle (HSA) shows azimuth and orientation.
• Vertical shadow angle (VSA) uses the formula VSA = arctan( tan(altitude) / cos(HSA)) to determine shading.