Daylighting | Components of Daylight factor
Daylighting is the practice of the designing various types of openings to admit daylight into the working space for efficient and comfortable living. The orientation, shape and size of the openings play an important role in daylighting.
Daylighting could be provided with the help of windows, skylights, courtyards etc.
Daylight factor can be defined as the sum of all daylight reaching an indoor reference point.
The three important components considered for the estimation of total amount of daylight reaching a particular point is as follows:
- Direct light of the sun
- External surfaces reflecting light directly to the point
- Internal surfaces reflecting and interreflecting light to the point
Each of the three components when expressed as a ratio or percent of the simultaneous external illuminance defines the sky component (SC), external reflected component (ERC) and internal reflected component.
Daylighting is usually considered on a horizontal plane since the work plane is horizontal (flooring, seating areas, work areas etc).
Factors in vertical planes are also considered for specifying daylighting values for special cases. For example, vertical daylighting is necessary in classrooms for illuminating noticeboards, blackboards, pictures and paintings that are hung on the wall.
Type of Daylighting
The type of daylighting depends on the task to be performed in that space.
For example, the type of daylighting required in a classroom is different from that required in a residence.
The type of daylighting required for a residence is solely evaluated in terms of horizontal plane except for any specific room which is to be utilized for other activites like painting. Or any room which is going to be used as an exhibit room.
Whereas classrooms should be enlightened with natural light considering both the planes, that is, horizontal and vertical planes.