Daylighting Design

Comprehensive knowledge base for natural daylighting strategies, solar geometry, shading device design, glare control, artificial lighting integration, and visual comfort optimization. Invoke this skill when addressing questions about window design, daylight simulation, shading calculations, lighting zones, circadian lighting, daylight metrics (sDA, ASE, UDI, DF), or any design decision involving natural light in buildings.

Section 1: Daylight Metrics

1.1 Daylight Factor (DF)

The Daylight Factor is the ratio of internal illuminance at a point on the working plane to the simultaneous unobstructed external horizontal illuminance under a CIE overcast sky, expressed as a percentage.

Formula: DF (%) = (E_internal / E_external) × 100

Components:

• Sky Component (SC) — direct light from visible sky through the window
• Externally Reflected Component (ERC) — light reflected from external surfaces (ground, adjacent buildings)
• Internally Reflected Component (IRC) — light reflected from internal room surfaces (ceiling, walls, floor)