LIGHT SHELVES
In a deep-plan work space, traditional side windows result in a non-uniform natural light distribution within the space. Areas which are more than a few feet from the wall can be gloomy, while those close to the window may well receive too much light and be subject to glare which makes conditions unsuitable for work with VDU’s. The traditional way of dealing with the glare is to use an internal roller shade or venetian blind; this, however, would further reduce light levels in the main body of the office.
A more effective daylighting system would be one which projects daylight further into the office, whilst at the same time shading the perimeter zone. In order to obtain good quality lighting, light should appear to come from above to more effectively illuminate the work surface. One way of achieving this is by using a light shelf.
A combination of external sunshade and light shelf
A light shelf is a horizontal element installed within a window to divide it into two sections. The light shelf is opaque, with a highly reflective upper surface and a diffusing white under surface. Generally, the light shelf will split the window with one third of the glazing above and two thirds below. This will allow reflection of both daylight and sunlight up on to the ceiling, whilst not obstructing the view through the window.
Light shelves are not standard items, they are generally designed to meet the specific project requirements. As a result, it is possible for them to incorporate items such as uplighters, task lighting and roller shades or specialty venetian blinds to shade the lower part of the glazing.
Additionally, it is possible to motorize the light shelf, enabling the angle of the shelf to be adjusted to make the optimum use of the available daylight. Another possibility is a hinged light shelf, allowing access to the glazing (and the upper surface of the light shelf) for cleaning.
Through installation of the light shelf, the depth of the perimeter zone can be almost doubled. Light levels within the outer part of the perimeter zone are reduced as compared to the situation without the light shelf, but are still above the level generally recommended as a minimum for office space (400 lux). The impact of light shelves is shown in the diagram below.
In overall terms, a light shelf will not result in more light inside the office – it will result in a more even light gradient, however and as a result, occupants in the building tend to turn on artificial lighting later than would otherwise be the case, with consequent cost savings.
For additional information contact Nysan at 403.204.8675