Supplementary Artifical Lighting

SUPPLEMENTARY ARTIFICAL LIGHTING

Definition

Supplementary artificial lighting is combination artifical lighting and daylighting which are a system of combined together to provide an even illumination.

The parts of the room are permanently lit by artificial light.

Explanation

• The purpose of supplementing daylight with artificial light is to lit those building spaces where the daylight level is inadequate.

• Particularly, in the case of multi-story buildings there is a tendency for ceiling heights to be low and rooms to be deep, so that the maximum number of floors can be accommodated within a minimum building height.

• Moreover, large windows are likely to lead to conditions of sky - glare and excessive heat transfer.

• It is difficult to provide adequate daylight in side-lit rooms with a depth greater than three times the window head height (6m approx).

• For rooms deeper than this a system known as PSALI (Permanent Supplementary Artificial Lighting of the Interiors) has been developed.

• Interior parts of the room are lit permanently by electric lights to provide necessary illumination.

• PSALI systems are designed that artificial illumination levels where natural light is inadequate and should mitigate the appearance of gloom in those parts of a building space that are remote from external windows.

• As a rule of thumb, the artificial lighting level (EPSALI) that is required in support of a PSALI ni 20 installation may be related to the average value of the Daylight.

Factor (DF _average) in the room under consideration, as follows:

It is suggested that the section of the room where this PSALI lighting is required may be confined to the area where the Daylight Factor is 20 percent or less of that near the window.