A light shelf is an architectural element which is designed to scatter natural light into a room, reducing the need for artificial lighting. Light shelves also provide shade near the windows, reducing glare and keeping rooms cool when temperatures rise. This design feature can be integrated into a building when it is constructed, or added later to increase energy efficiency. Along with things like skylights and light tubes, light shelves are considered “daylighting” devices, meaning that they are designed to cut down on the use of artificial lighting during the day.
In order for a light shelf to be effective, the ceilings in the room typically need to be high, to provide a lot of room for the light. The shelf is placed above eye level in a window, and it can be located either indoors or outdoors. On the upper surface, the light shelf is coated in reflective material so that when light hits it, the light bounces off and hits the ceiling, pushing light deep into the room. When the room is painted in pale colors, these light colors combined with the light shelf are often enough to illuminate the space without the need for a lamp.
In the northern hemisphere, light shelves are usually deployed along the southern edge of a building, so that they will be able to catch the most sunlight. This is reversed in the southern hemisphere, where light shelves need to be positioned on the north side of a building for maximum exposure. In both cases, the light shelves need to be regularly maintained to ensure that they are as reflective as possible so that they will continue to be effective.
The major drawback to a light shelf is that it only works on sunny days. When the sky is overcast, the light shelf will be able to scatter some light, but not enough to make a significant difference, and it will usually be necessary to supplement with artificial light. These architectural elements can be designed to mesh with the look and feel of a building so that they are not obtrusive, although they will certainly be visible. When the shelves are installed indoors, people must be reminded not to store or display objects on the shelf, as this can interrupt the flow of light.
In addition to increasing energy efficiency by eliminating the need for artificial light during the day, light shelves can also benefit the health and psychological well being of people who use the spaces they illuminate. Natural light appears to be highly beneficial, especially when contrasted with lighting options such as fluorescent lighting, and it can also make a space more pleasant to work in, thereby increasing worker satisfaction.