Building with the Sun
The sun is a building's most powerful environmental force — it provides free light and heat in winter but causes overheating and glare in summer. Solar orientation, the art of positioning buildings to harness sunlight optimally, has been practiced since antiquity. Greek cities were laid out so homes faced south for winter warmth. Roman law protected solar access rights. Today, with energy costs rising, solar-responsive design is more important than ever.
The Sun's Geometry
The sun's path across the sky changes with latitude and season. At 45°N latitude, the summer solstice sun climbs to 68° above the horizon and shines for over 15 hours; the winter solstice sun reaches only 22° and shines for barely 9 hours. Understanding these angles is essential for designing facades, overhangs, and shading devices. This simulation traces the sun's path and shows exactly how it strikes building surfaces throughout the year.
Facade Orientation Strategy
A south-facing facade in the Northern Hemisphere is the architect's best friend. In winter, the low sun streams directly through south windows, providing free solar heating. In summer, the high sun can be blocked by a simple horizontal overhang. East and west facades are problematic — the low morning and afternoon sun is nearly impossible to shade with fixed overhangs, causing glare and overheating. North facades receive only diffuse light, useful for studios and galleries where direct sun is unwanted.
Window-to-Wall Ratio and Daylighting
The window-to-wall ratio (WWR) balances daylight, views, heat gain, and energy loss. More glass means more natural light (reducing electric lighting energy) but also more heat transfer. Modern energy codes typically cap WWR at 40%, but high-performance glazing with low-e coatings can push this higher. The key insight is that orientation matters more than quantity — a 30% WWR on a south facade outperforms a 60% WWR facing west for both comfort and energy.