Daylight factor
Learn how to calculate and improve the ratio of light level inside a structure to the light level outside. Find out the design guidance and software tools for daylighting assessment and simulation.
The daylight factor is the index that defines the correct ventilation and lighting of a dwelling. Discover why it is important and how it is calculated.
Daylight Factor
Daylight Factor (DF) is defined as the ratio of daylight illumination at a specific point on a plane, due to both direct and indirect light from the sky, to the illumination on a horizontal plane under an unobstructed hemisphere of the same sky. It is expressed as a percentage and is used to assess the amount of natural light in a space, excluding direct sunlight. AI generated definition based ...
Daylight factor (DF) is a daylight availability metric that expresses as a percentage the amount of daylight available inside a room (on a work plane) compared to the amount of unobstructed daylight available outside under overcast sky conditions (Hopkins,1963). The key building properties that determine the magnitude and distribution of the daylight factor in a space are (Mardaljevic, J ...
Free Daylight Factor Calculator
Free daylight factor calculator for architects and lighting designers. Calculate DF = Ei/Eo × 100%, sky component, internally reflected component. Check LEED v4.1 sDA 300/50%, WELL, and EN17037 daylight requirements. Glass type presets, material finishes, skylight support, and interactive DF probe tool. Try it free!
For purposes of calculating daylight factors associated with beam solar illuminance, the direct normal solar illuminance is taken to be 1.0 W/m 2. The actual direct normal solar illuminance, determined from direct normal solar irradiance from the weather file and empirically-determined luminous efficacy, is used in the time-step calculation.
Daylight Factor Calculator
The Daylight Factor Calculator estimates how much useful daylight reaches an interior space by comparing indoor daylight illuminance with simultaneous outdoor daylight illuminance under a standard overcast-sky assumption. It returns the daylight factor as a percentage and also shows indoor illuminance and outdoor reference illuminance. This calculator is intended for daylight adequacy ...
4 The implications of using Daylight Factor as the basis for assessing compliance with Building Codes/Regulations and/or Environmental assessment Method Credits. 5 What are the alternatives to Daylight Factor ? 5.1 Daylight Autonomy 5.2 Useful Daylight Illuminance 5.3 Cumulative illuminance 6 Conclusion 7 Acknowledgement 8 Other definitions
Daylight Factor Calculator
The Daylight Factor (DF) is a standardized metric that quantifies the percentage of available outdoor daylight that reaches a specific indoor point. This calculation serves as a fundamental tool in architectural daylighting design, enabling professionals to assess natural light penetration and distribution within built environments.
Learn how daylighting factor is calculated and how it varies for different types of buildings and spaces. See examples of daylighting factor values for dwellings, schools, offices, hospitals and more.