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Daylight factor measures indoor daylight availability as percentage of outdoor illuminance. It determines whether artificial lighting is required.

Formula

Daylight factor = (indoor illumination / outdoor illumination) × 100%

Guida passo passo

  1. 1Daylight factor = (indoor illumination / outdoor illumination) × 100%
  2. 2Values: <2% (supplementary lighting needed), 2-5% (adequate), >5% (well-lit)
  3. 3Depends on window size, orientation, obstruction

Esempi risolti

Ingresso
Indoor illumination 100 lux, outdoor 5000 lux
Risultato
Daylight factor = 2% (borderline, likely needs supplementary lighting)
Typical office

Errori comuni da evitare

  • Over-sizing windows in climate with high cooling loads
  • Neglecting glare control in high daylight factor spaces

Domande frequenti

Does orientation affect daylight factor?

Significantly; south-facing windows get stable light, north-facing less direct but more diffuse.

How do you improve daylight factor?

Increase window area, use reflective interior surfaces, reduce obstructions, add skylights.

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