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Public building gets which type of illumination scheme?
Direct lighting
Indirect lighting
Reflected lighting
All of above
Direct lighting
Public buildings, such as offices and schools, primarily utilize direct lighting schemes because they provide high efficiency and intensity directly onto the work plane. In a direct lighting system, more than 90% of the light flux is directed downwards onto the surface to be illuminated, minimizing waste and improving visibility for tasks.
Public buildings, such as offices and schools, primarily utilize direct lighting schemes because they provide high efficiency and intensity directly onto the work plane. In a direct lighting system, more than 90% of the light flux is directed downwards onto the surface to be illuminated, minimizing waste and improving visibility for tasks.
E=d2Icos╬╕тАЛ тАФ Basic law of illumination representing intensity at a point
The principle relies on the inverse square law of illumination, where intensity decreases with the square of the distance. By placing luminaires close to the workspace, direct lighting achieves high coefficients of utilization. Reflectors are often integrated with the light source to ensure a focused beam, reducing the amount of light absorbed by ceilings or walls.
Direct lighting provides the highest coefficient of utilization among standard lighting schemes.
It is cost-effective but can cause harsh shadows and glare if not properly designed with diffusers.
Commonly used in large halls, offices, and industrial workshops where task-focused illumination is required.
High efficiency
Economical installation
Effective for local illumination
Prone to hard shadows
Potential for glare
Uneven illumination if luminaires are spaced too far
Office workstations
Classrooms
Industrial production lines
| Feature | Direct Lighting | Indirect Lighting |
|---|---|---|
Efficiency | High (>90%) | Low (10-30%) |
Indirect lighting directs light towards the ceiling for reflection, creating a softer environment but requiring much higher power wattage.
Reflected lighting uses surfaces to diffuse light, ideal for decorative purposes rather than high-precision tasks.
A is correct тАФ Direct lighting is the preferred scheme for public buildings to achieve maximum light intensity on the working plane with high efficiency.
Always relate 'Coefficient of Utilization' to the mounting height and room dimensions in lighting design problems.