##  [Daylight Factor](/daylight-factor) 

  ##  [Daylight Factor](https://engineering.quantumdictionary.io/daylight-factor-0) 

  

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**Engineering & Applied Technologies Dictionary**

 







 

 

 

 



 

 

 

 

Definition

The ratio, expressed as a percentage, of the interior horizontal illuminance at a point on a reference plane under an overcast sky to the simultaneous unobstructed exterior horizontal illuminance under the same sky; used as a standardized, steady‑state indicator of natural lighting performance independent of direct sunlight.