[harshita]

Day lighting
The primary source of lighting for daylighting is the sun. The light received by the earth from the sun consists of two parts, namely, direct solar illuminance and sky illuminance
For the purposes of daylighting design, direct solar illuminance shall not be considered and only sky illuminance shall be taken as contributing to illumination of the building interiors during the day.
Daylight factor (DF) is the ratio of the light level inside a structure to the light level outside the structure.

Ei = illumiance due to daylight at a point on the indoors working plane
Eo = simultaneous outdoor illuminance on a horizontal plane from an unobstructed hemisphere of overcast sky

To know more about illumination read ....Day lighting
Illumination in architecture

[Manish Jain]

The primary source of lighting for daylighting is the sun.

In daylighting design, the goal is to maximize the use of natural light while minimizing the negative effects of glare and heat gain. This can be achieved through a range of strategies, including the use of daylight-responsive controls, such as automated shading systems and sensors that adjust electric lighting in response to changes in natural light levels.

The light received by the earth from the sun consists of two parts, namely, direct solar illuminance and sky illuminance

Sky illuminance is influenced by a range of factors, including the time of day, weather conditions, and the orientation and location of the building. In general, the amount of sky illuminance that is available is highest at midday on a clear day, and decreases as the sun moves closer to the horizon or as cloud cover increases.

In daylighting design, sky illuminance is often measured in units of lux, which indicate the amount of light that is received per unit of area. Sky illuminance can be predicted using computer simulations and models that take into account a range of variables, including the orientation and location of the building, the size and placement of windows, and the reflectivity of surrounding surfaces.

By carefully considering the amount of sky illuminance that is available in a space, lighting professionals can design lighting systems that maximize the use of natural light and minimize the need for electric lighting. This can help to reduce energy consumption and improve overall occupant comfort and well-being.

For the purposes of daylighting design, direct solar illuminance shall not be considered and only sky illuminance shall be taken as contributing to illumination of the building interiors during the day.