Windows receive a large amount of energy from the sun. Most of this is wasted on a single area, and direct sunlight causes harmful glare on desks and computer monitors. In fact, a single south-facing window can illuminate up to 20 to 100 times its unit area. This light can be a nuisance if concentrated in one spot, but is extremely useful if distributed to all parts of the room equally.
Light shelves bounce visible light up towards the ceiling, which reflect it down deeper into the interior of a room. External and internal light shelves mounted on the south- and west-facing windows in the IL Centre redistribute light into the office space and group rooms, providing natural brightness to the building and reducing the need for daytime overhead lighting.
For best results, light shelves should be mounted horizontally. If the surface of the shelf is highly reflective, then the angle that the sunlight is reflected onto the ceiling will be equal to the angle of incidence of the incoming sunlight.For a more diffuse spread of light, shelves can be painted with rougher, less mirror-like materials. This will scatter the light at many different angles, providing a more diverse coverage area on the ceiling. The ceiling should be painted with a reflective paint in a light colour, to bounce the light back down onto the work area.
Each internal light shelf is mounted 2.1 meters (7 feet) high, to eliminate the possibility that glare will be reflected into the eyes. There is also a safety reason for this: internal shelves must be above head-height. External shelves are best paired with internal shelves and mounted at the same height.
Blinds are installed above and below the light shelves in the IL Centre, so that users are able to adjust the brightness of the room for individual comfort at different times of day.
Direct sunlight can heat up a room by several degrees, an effect is called solar heat gain. Because of the light dispersal effect, the heat energy that is added to a room by a light shelf is only slightly more than the heat generated by standard electric lighting. The benefit, of course, is the power consumption for this lighting - none.