Light Shelf

In my latest blog post I described how traditional shading systems can actually increase the illumination in a room. However, one of the drawbacks by use of such shading systems is that they obstruct the view to the outside. In this blog post I will introduce some innovative systems that reduce this problem.

Light shelf is a shading system that redirects the sunlight and helps it penetrate further into the room. A light shelf is designed to reflect the direct sunlight to reduce the probability of glare problems. It also improves the light conditions by distributing light further into the room. As illustrated in Figure 1:

light shelf

Figure 1. Light shelf distributing sunlight. Illustration from

Light shelves may be installed either on the inside or the outside of the wall. Placing the light shelf on the inside will reduce the available room space. However, a shelf placed on the outside will require more maintenance.

As we can see from the illustration above the shelf will now obstruct the view like traditional blinds does. However, in many conditions a light shelf alone will not be adequate shading. But it will indeed help utilizing the natural daylight.

The light shelf will actually reflect more light if it lowered. But lowering the shelf will both increase the likelihood of glare and obstruct the view to the outside.


Beltran, L. O. Lee, E. S. and Selkowitz, S. E. (1996) Advanced Optical Daylighting Systems: Light Shelves and Light Pipes. Journal of the Illuminating Engineering Society. 26 (2) (1997), pp. 91–106.

Ruck, N. (2000) Daylight in Buildings – a source book on daylighting systems and components. Lawrence Berkeley National Laboratory. Berkeley.


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