Every site on Earth has a unique relationship with the sun. The angle at which sunlight strikes a building changes hour by hour and season by season, and those shifts directly shape heating loads, cooling demands, daylighting quality, and occupant comfort. Before you can select shading devices or size overhangs, you need to understand two core measurements: solar altitude (the sun's angle above the horizon) and solar azimuth (its compass bearing from due south). Together, these define the sun's position at any moment.

For the PPD exam, this topic sits at the front of the design process. NCARB expects you to locate a building on its site based on solar path, among other factors, and that means evaluating how orientation choices affect energy performance and interior conditions. You won't just recall definitions. You'll analyze trade-offs: a building rotated 15 degrees off the east-west axis gains morning warmth but may overheat in summer. A deep floor plate on the south side captures winter sun but complicates daylighting at the core.

Sun path diagrams are your primary tool here. They plot the sun's arc across the sky vault for each month, letting you read altitude and azimuth at a glance. Once you can read that diagram, you can predict when direct sun will hit a given facade, how deep it will penetrate a room, and whether a fixed overhang will block summer sun while admitting winter sun. That prediction chain, from solar geometry to design decision, is what NCARB tests at the A/E level.