Using CAD for Lighting Design Helps Predict the Unpredictable

Part of a lighting designers craft is to imagine the appearance of an illuminated area before it is built. Experienced designers, however, can be surprised once construction begins. New uses of construction materials, new techniques and experimentation often lead to profitable discoveries as well as occasional mistakes. Design exploration is to be encouraged, as long as it does not conflict with a clients preference. Unfortunately, a client may insist on an unwise choice, resulting in confrontation and potential dissatisfaction. For these reasons and others, designers and their clients frequently prefer to preview many decisions before they are made.

Computers offer the ability to predict variables in design including appearance, thereby making designer and client education more economical. By simulating the behavior of light, computers can predict luminance and illuminance levels, and make synthetic images of a space before it is built. In lighting design, a common practice is to begin with a target illuminance distribution, then use manufacturers tables and simple calculations to arrive at an initial lighting arrangement. For critical areas, flexibility is built into the system so that the light distribution can be tuned during installation. This approach works well in most applications, but when daylighting is a key feature, or aesthetics are stressed over illumination levels, it becomes much more difficult for the designer to be convinced, and even harder to convince the client of a quality design. In this situation computer prediction of appearance would be invaluable.